Indicate which of the following are exact numbers:(a) the mass of a 3- by 5-in. index

Which of the following figures represents (a) a pure element, (b) a mixture of two elements, (c) a pure compound, (d) a mixture of an element and a compound? (More than one picture might fit each description.) [Section 1.2]

Which of the following diagrams represents a chemical change? [Section 1.3]

Musical instruments like trumpets and trombones are made from an alloy called brass. Brass is composed of copper and zinc atoms and appears homogeneous under an optical microscope. The approximate composition of most brass objects is a 2:1 ratio of copper to zinc atoms, but the exact ratio varies somewhat from one piece of brass to another. (a) Would you classify brass as an element, a compound, a homogeneous mixture, or a heterogeneous mixture? (b) Would it be correct to say that brass is a solution? [Section 1.2]

Consider the two spheres shown here, one made of silver and the other of aluminum. (a) What is the mass of each sphere in kg? (b) The force of gravity acting on an object is F = mg, where m is the mass of an object and g is the acceleration of gravity (9.8 m/s2). How much work do you do on each sphere if you raise it from the floor to a height of 2.2 m? (c) Does the act of lifting the sphere off the ground increase the potential energy of the aluminum sphere by a larger, smaller, or same amount as the silver sphere? (d) If you release the spheres simultaneously, they will have the same velocity when they hit the ground. Will they have the same kinetic energy? If not, which sphere will have more kinetic energy? [Section 1.4]

Is the separation method used in brewing a cup of coffee best described as distillation, filtration, or chromatography? [Section 1.3]

Identify each of the following as measurements of length, area, volume, mass, density, time, or temperature: (a) 25 ps, (b) 374.2 mg, (c) 77 K, (d) 100,000 km2, (e) 1.06 ?m, (f) 16 nm2, (g) -78 °C, (h) 2.56 g/cm3, (i) 28 cm3. [Section 1.5]

All of the hydrogens are bonded to carbon in both of the following. Write a Lewis formula that satisfies the octet rule for each. (a) Formaldehyde \(\left(\mathrm{CH}_{2} \mathrm{O}\right)\) (b) Hydrogen cyanide (HCN) Text Transcription: CH_2 O

The three targets from a rifle range shown below were produced by: (A) the instructor firing a newly acquired target rifle; (B) the instructor firing his personal target rifle; and (C) a student who has fired his target rifle only a few times. (a) Comment on the accuracy and precision for each of these three sets of results. (b) For the A and C results in the future to look like those in B, what needs to happen? [Section 1.6]

(a) What is the length of the pencil in the following figure if the ruler reads in centimeters? How many significant figures are there in this measurement? (b) An automobile speedometer with circular scales reading both miles per hour and kilometers per hour is shown. What speed is indicated, in both units? How many significant figures are in the measurements? [Section 1.6]

(a) How many significant figures should be reported for the volume of the metal bar shown here? (b) If the mass of the bar is 104.72 g, how many significant figures should be reported when its density is determined using the calculated volume? [Section 1.6]

Consider the jar of jelly beans in the photo. To get an estimate of the number of beans in the jar you weigh six beans and obtain masses of 3.15, 3.12, 2.98, 3.14, 3.02, and 3.09 g. Then you weigh the jar with all the beans in it, and obtain a mass of 2082 g. The empty jar has a mass of 653 g. Based on these data, estimate the number of beans in the jar. Justify the number of significant figures you use in your estimate. [Section 1.6]

The photo below shows a picture of an agate stone. Jack, who picked up the stone on the Lake Superior shoreline and polished it, insists that agate is a chemical compound. Ellen argues that it cannot be a compound. Discuss the relative merits of their positions. [Section 1.2]

Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (a) rice pudding, (b) seawater, (c) magnesium, (d) crushed ice.

Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous: (a) air, (b) tomato juice, (c) iodine crystals, (d) sand.

Give the chemical symbol or name for the following elements, as appropriate: (a) sulfur, (b) gold, (c) potassium, (d) chlorine, (e) copper, (f) U, (g) Ni, (h) Na, (i) Al, (j) Si.

Give the chemical symbol or name for each of the following elements, as appropriate: (a) carbon, (b) nitrogen, (c) titanium, (d) zinc, (e) iron, (f) P, (g) Ca, (h) He, (i) Pb, (j) Ag.

A solid white substance A is heated strongly in the absence of air. It decomposes to form a new white substance B and a gas C. The gas has exactly the same properties as the product obtained when carbon is burned in an excess of oxygen. Based on these observations, can we determine whether solids A and B and gas C are elements or compounds?

You are hiking in the mountains and find a shiny gold nugget. It might be the element gold, or it might be “fool’s gold,” which is a nickname for iron pyrite, FeS2. Which of the following physical properties do you think would help determine if the shiny nugget is really gold—appearance, melting point, density, or physical state?

In the process of attempting to characterize a substance, a chemist makes the following observations: The substance is a silvery white, lustrous metal. It melts at 649 °C and boils at 1105 °C. Its density at 20 °C is 1.738 g/cm3. The substance burns in air, producing an intense white light. It reacts with chlorine to give a brittle white solid. The substance can be pounded into thin sheets or drawn into wires. It is a good conductor of electricity. Which of these characteristics are physical properties, and which are chemical properties?

(a) Read the following description of the element zinc and indicate which are physical properties and which are chemical properties. Zinc melts at 420 °C. When zinc granules are added to dilute sulfuric acid, hydrogen is given off and the metal dissolves. Zinc has a hardness on the Mohs scale of 2.5 and a density of 7.13 g/cm3 at 25 °C. It reacts slowly with oxygen gas at elevated temperatures to form zinc oxide, ZnO. (b) Which properties of zinc can you describe from the photo? Are these physical or chemical properties?

Label each of the following as either a physical process or a chemical process: (a) rusting of a metal can, (b) boiling a cup of water, (c) pulverizing an aspirin, (d) digesting a candy bar, (e) exploding of nitroglyerin.

A match is lit and held under a cold piece of metal. The following observations are made: (a) The match burns. (b) The metal gets warmer. (c) Water condenses on the metal. (d) Soot (carbon) is deposited on the metal. Which of these occurrences are due to physical changes, and which are due to chemical changes?

Which separation method is better suited for separating a solution of sugar and water into pure substances, filtration or distillation?

Two beakers contain clear, colorless liquids. When the contents of the beakers are mixed a white solid is formed. (a) Is this an example of a chemical or a physical change? (b) What would be the most convenient way to separate the newly formed white solid from the liquid mixture—filtration, distillation, or chromatography.

(a) Calculate the kinetic energy, in joules of a 1200-kg automobile moving at 18 m/s. (b) Convert this energy to calories. (c) When the automobile brakes to a stop is the “lost” kinetic energy converted mostly to heat or to some form of potential energy?

(a) A baseball weighs 5.13 oz. What is the kinetic energy, in joules, of this baseball when it is thrown by a major league pitcher at 95.0 mi/h? (b) By what factor will the kinetic energy change if the speed of the baseball is decreased to 55.0 mi/h? (c) What happens to the kinetic energy when the baseball is caught by the catcher? Is it converted mostly to heat or to some form of potential energy?

Two positively charged particles are first brought close together and then released. Once released, the repulsion between particles causes them to move away from each other. (a) This is an example of potential energy being converted into what form of energy? (b) Does the potential energy of the two particles prior to release increase or decrease as the distance between them is increased.

For each of the following processes, does the potential energy of the object(s) increase or decrease? (a) The distance between two oppositely charged particles is increased. (b) Water is pumped from ground level to the reservoir of a water tower 30 m above the ground. (c) The bond in a chlorine molecule, Cl2, is broken to form two chlorine atoms.

What is the kinetic energy and velocity of the aluminum sphere in Problem 1.4 at the moment it hits the ground? (Assume that energy is conserved during the fall and that 100% of the sphere’s initial potential energy is converted to kinetic energy by the time impact occurs.)

What is the kinetic energy and velocity of the silver sphere in Problem 1.4 at the moment it hits the ground? (Assume that energy is conserved during the fall and that 100% of the sphere’s initial potential energy is converted to kinetic energy by the time impact occurs.)

What exponential notation do the following abbreviations represent? (a) d, (b) c, (c) f, (d) ?, (e) M, (f) k, (g) n, (h) m, (i) p.

Use appropriate metric prefixes to write the following measurements without use of exponents: (a) 2.3 10-10 L, (b) 4.7 10-6 g, (c) 1.85 10-12 m, (d) 16.7 106 s, (e) 15.7 103 g, (f) 1.34 10-3 m, (g) 1.84 102 cm.

Make the following conversions: (a) 72 °F to °C, (b) 216.7 °C to °F, (c) 233 °C to K, (d) 315 K to °F, (e) 2500 °F to K, (f) 0 K to °F.

(a) The temperature on a warm summer day is 87 °F. What is the temperature in °C? (b) Many scientific data are reported at 25 °C. What is this temperature in kelvins and in degrees Fahrenheit? (c) Suppose that a recipe calls for an oven temperature of 400 °F. Convert this temperature to degrees Celsius and to kelvins. (d) Liquid nitrogen boils at 77 K. Convert this temperature to degrees Fahrenheit and to degrees Celsius.

(a) A sample of tetrachloroethylene, a liquid used in dry cleaning that is being phased out because of its potential to cause cancer, has a mass of 40.55 g and a volume of 25.0 mL at 25 °C. What is its density at this temperature? Will tetrachloroethylene float on water? (Materials that are less dense than water will float.) (b) Carbon dioxide (CO2) is a gas at room temperature and pressure. However, carbon dioxide can be put under pressure to become a “supercritical fluid” that is a much safer dry-cleaning agent than tetrachloroethylene. At a certain pressure, the density of supercritical CO2 is 0.469 g/cm3. What is the mass of a 25.0-mL sample of supercritical CO2 at this pressure?

(a) A cube of osmium metal 1.500 cm on a side has a mass of 76.31 g at 25 °C. What is its density in g/cm3 at this temperature? (b) The density of titanium metal is 4.51g/cm3 at 25 °C. What mass of titanium displaces 125.0 mL of water at 25 °C? (c) The density of benzene at 15 °C is 0.8787 g/mL. Calculate the mass of 0.1500 L of benzene at this temperature.

(a) To identify a liquid substance, a student determined its density. Using a graduated cylinder, she measured out a 45-mL sample of the substance. She then measured the mass of the sample, finding that it weighed 38.5 g. She knew that the substance had to be either isopropyl alcohol (density 0.785 g/mL) or toluene (density 0.866 g/mL). What is the calculated density and the probable identity of the substance? (b) An experiment requires 45.0 g of ethylene glycol, a liquid whose density is 1.114 g/mL. Rather than weigh the sample on a balance, a chemist chooses to dispense the liquid using a graduated cylinder. What volume of the liquid should he use? (c) Is a graduated cylinder such as that shown in Figure 1.21 likely to afford the accuracy of measurement needed? (d) A cubic piece of metal measures 5.00 cm on each edge. If the metal is nickel, whose density is 8.90 g/cm3, what is the mass of the cube?

(a) After the label fell off a bottle containing a clear liquid believed to be benzene, a chemist measured the density of the liquid to verify its identity. A 25.0-mL portion of the liquid had a mass of 21.95 g. A chemistry handbook lists the density of benzene at 15 °C as 0.8787 g/mL. Is the calculated density in agreement with the tabulated value? (b) An experiment requires 15.0 g of cyclohexane, whose density at 25 °C is 0.7781 g/mL. What volume of cyclohexane should be used? (c) A spherical ball of lead has a diameter of 5.0 cm. What is the mass of the sphere if lead has a density of 11.34 g/cm3? (The volume of a sphere is 14/32r3, where r is the radius.)

In the year 2013, an estimated amount of 36 billion metric tons (1 metric ton = 1000 kg) of carbon dioxide (CO2) was emitted worldwide due to fossil fuel combustion and cement production. Express this mass of CO2 in grams without exponential notation, using an appropriate metric prefix.

Silicon for computer chips is grown in large cylinders called “boules” that are 300 mm in diameter and 2 m in length, as shown. The density of silicon is 2.33 g/cm3. Silicon wafers for making integrated circuits are sliced from a 2.0-m boule and are typically 0.75 mm thick and 300 mm in diameter. (a) How many wafers can be cut from a single boule? (b) What is the mass of a silicon wafer? (The volume of a cylinder is given by ?r2h, where r is the radius and h is its height.)

Use of the British thermal unit (Btu) is common in some types of engineering work. A Btu is the amount of heat required to raise the temperature of 1 lb of water by 1°F. Calculate the number of joules in a Btu.

A watt is a measure of power (the rate of energy change) equal to 1 J/s. (a) Calculate the number of joules in a kilowatt-hour. (b) An adult person radiates heat to the surroundings at about the same rate as a 100-watt electric incandescent light bulb. What is the total amount of energy in kcal radiated to the surroundings by an adult over a 24 h period?

Indicate which of the following are exact numbers: (a) the mass of a 3- by 5-in. index card, (b) the number of ounces in a pound, (c) the volume of a cup of Seattle’s Best coffee, (d) the number of inches in a mile, (e) the number of microseconds in a week, (f) the number of pages in this book.

Indicate which of the following are exact numbers: (a) the mass of a 32-oz can of coffee, (b) the number of students in your chemistry class, (c) the temperature of the surface of the Sun, (d) the mass of a postage stamp, (e) the number of milliliters in a cubic meter of water, (f) the average height of NBA basketball players.

What is the number of significant figures in each of the following measured quantities? (a) 601 kg, (b) 0.054 s, (c) 6.3050 cm, (d) 0.0105 L, (e) 7.0500 10-3 m3, (f) 400 g.

Indicate the number of significant figures in each of the following measured quantities: (a) 3.774 km, (b) 205 m2, (c) 1.700 cm, (d) 350.00 K, (e) 307.080 g, (f) 1.3 103 m/s

Round each of the following numbers to four significant figures and express the result in standard exponential notation: (a) 102.53070, (b) 656.980, (c) 0.008543210, (d) 0.000257870, (e) -0.0357202.

(a) The diameter of Earth at the equator is 7926.381 mi. Round this number to three significant figures and express it in standard exponential notation. (b) The circumference of Earth through the poles is 40,008 km. Round this number to four significant figures and express it in standard exponential notation.

Carry out the following operations and express the answers with the appropriate number of significant figures. (a) 14.3505 + 2.65 (b) 952.7 - 140.7389 (c) (3.29 104)(0.2501) (d) 0.0588/0.677

Carry out the following operations and express the answer with the appropriate number of significant figures. (a) 320.5 - (6104.5/2.3) (b) [(285.3 105) - (1.200 103)] 2.8954 (c) (0.0045 20,000.0) + (2813 12) (d) 863 [1255 - (3.45 108)]

You weigh an object on a balance and read the mass in grams according to the picture. How many significant figures are in this measurement?

You have a graduated cylinder that contains a liquid (see photograph). Write the volume of the liquid, in milliliters, using the proper number of significant figures.

For each of the following molecules that contain polar covalent bonds, indicate the positive and negative ends of the dipole, using the symbol \(\longmapsto\). Refer to Table 1.3 as needed. (a) HCl (b) HI (c) \(\mathrm{H_2O}\) (d) HOCl Text Transcription: \longmapsto \mathrm{H_2O}

Using your knowledge of metric units, English units, and the information on the back inside cover, write down the conversion factors needed to convert (a) ?m to mm, (b) ms to ns, (c) mi to km, (d) ft3 to L.

(a) A bumblebee flies with a ground speed of 15.2 m/s. Calculate its speed in km/hr. (b) The lung capacity of the blue whale is 5.0 103 L. Convert this volume into gallons. (c) The Statue of Liberty is 151 ft tall. Calculate its height in meters. (d) Bamboo can grow up to 60.0 cm/day. Convert this growth rate into inches per hour.

(a) The speed of light in a vacuum is 2.998 108 m/s. Calculate its speed in miles per hour. (b) The Sears Tower in Chicago is 1454 ft tall. Calculate its height in meters. (c) The Vehicle Assembly Building at the Kennedy Space Center in Florida has a volume of 3,666,500 m3. Convert this volume to liters and express the result in standard exponential notation. (d) An individual suffering from a high cholesterol level in her blood has 242 mg of cholesterol per 100 mL of blood. If the total blood volume of the individual is 5.2 L, how many grams of total blood cholesterol does the individual’s body contain?

Perform the following conversions: (a) 5.00 days to s, (b) 0.0550 mi to m, (c) $1.89/gal to dollars per liter, (d) 0.510 in./ms to km/hr, (e) 22.50 gal/min to L/s, (f) 0.02500 ft3 to cm3.

Carry out the following conversions: (a) 0.105 in. to mm, (b) 0.650 qt to mL, (c) 8.75 ?m/s to km/hr, (d) 1.955 m3 to yd3 (e) $3.99/lb to dollars per kg, (f) 8.75 lb/ft3 to g/mL.

(a) How many liters of wine can be held in a wine barrel whose capacity is 31 gal? (b) The recommended adult dose of Elixophyllin®, a drug used to treat asthma, is 6 mg/kg of body mass. Calculate the dose in milligrams for a 185-lb person. (c) If an automobile is able to travel 400 km on 47.3 L of gasoline, what is the gas mileage in miles per gallon? (d) When the coffee is brewed according to directions, a pound of coffee beans yields 50 cups of coffee 14 cups = 1 qt2. How many kg of coffee are required to produce 200 cups of coffee?

(a) If an electric car is capable of going 225 km on a single charge, how many charges will it need to travel from Seattle, Washington, to San Diego, California, a distance of 1257 mi, assuming that the trip begins with a full charge? (b) If a migrating loon flies at an average speed of 14 m/s, what is its average speed in mi/hr? (c) What is the engine piston displacement in liters of an engine whose displacement is listed as 450 in.3? (d) In March 1989, the Exxon Valdez ran aground and spilled 240,000 barrels of crude petroleum off the coast of Alaska. One barrel of petroleum is equal to 42 gal. How many liters of petroleum were spilled?

The density of air at ordinary atmospheric pressure and 25 °C is 1.19 g/L. What is the mass, in kilograms, of the air in a room that measures 14.5 ft 16.5 ft 8.0 ft?

The concentration of carbon monoxide in an urban apartment is 48 ?g/m3. What mass of carbon monoxide in grams is present in a room measuring 10.6 ft 14.8 ft 20.5 ft?

Gold can be hammered into extremely thin sheets called gold leaf. An architect wants to cover a 100 ft 82 ft ceiling with gold leaf that is five-millionths of an inch thick. The density of gold is 19.32 g/cm3, and gold costs $1654 per troy ounce (1 troy ounce = 31.1034768 g). How much will it cost the architect to buy the necessary gold?

A copper refinery produces a copper ingot weighing 150 lb. If the copper is drawn into wire whose diameter is 7.50 mm, how many feet of copper can be obtained from the ingot? The density of copper is 8.94 g/cm3. (Assume that the wire is a cylinder whose volume V = ?r2h, where r is its radius and h is its height or length.)

Classify each of the following as a pure substance, a solution, or a heterogeneous mixture: (a) a gold ingot, (b) a cup of coffee, (c) a wood plank.

(a) Which is more likely to eventually be shown to be incorrect: an hypothesis or a theory? (b) A(n) _________ reliably predicts the behavior of matter, while a(n) _________ provides an explanation for that behavior.

A sample of ascorbic acid (vitamin C) is synthesized in the laboratory. It contains 1.50 g of carbon and 2.00 g of oxygen. Another sample of ascorbic acid isolated from citrus fruits contains 6.35 g of carbon. According to the law of constant composition, how many grams of oxygen does it contain?

Ethyl chloride is sold as a liquid (see photo) under pressure for use as a local skin anesthetic. Ethyl chloride boils at 12 °C at atmospheric pressure. When the liquid is sprayed onto the skin, it boils off, cooling and numbing the skin as it vaporizes. (a) What changes of state are involved in this use of ethyl chloride? (b) What is the boiling point of ethyl chloride in degrees Fahrenheit? (c) The bottle shown contains 103.5 mL of ethyl chloride. The density of ethyl chloride at 25 °C is 0.765 g/cm3. What is the mass of ethyl chloride in the bottle?

Two students determine the percentage of lead in a sample as a laboratory exercise. The true percentage is 22.52%. The students’ results for three determinations are as follows: (1) 22.52, 22.48, 22.54 (2) 22.64, 22.58, 22.62 (a) Calculate the average percentage for each set of data and state which set is the more accurate based on the average. (b) Precision can be judged by examining the average of the deviations from the average value for that data set. (Calculate the average value for each data set; then calculate the average value of the absolute deviations of each measurement from the average.) Which set is more precise?

Is the use of significant figures in each of the following statements appropriate? (a) The 2005 circulation of National Geographic was 7,812,564. (b) On July 1, 2005, the population of Cook County, Illinois, was 5,303,683. (c) In the United States, 0.621% of the population has the surname Brown. (d) You calculate your grade point average to be 3.87562.

What type of quantity (for example, length, volume, density) do the following units indicate? (a) mL, (b) cm2, (c) mm3, (d) mg/L, (e) ps, (f) nm (g) K.

Give the derived SI units for each of the following quantities in base SI units: (a) acceleration = distance/time2 (b) force = mass acceleration (c) work = force distance (d) pressure = force/area (e) power = work/time (f) velocity = distance/time (g) energy = mass (velocity)2

The distance from Earth to the Moon is approximately 240,000 mi. (a) What is this distance in meters? (b) The peregrine falcon has been measured as traveling up to 350 km/ hr in a dive. If this falcon could fly to the Moon at this speed, how many seconds would it take? (c) The speed of light is 3.00 108 m/s. How long does it take for light to travel from Earth to the Moon and back again? (d) Earth travels around the Sun at an average speed of 29.783 km/s. Convert this speed to miles per hour.

Which of the following would you characterize as a pure or nearly pure substance? (a) baking powder; (b) lemon juice; (c) propane gas, used in outdoor gas grills; (d) aluminum foil; (e) ibuprofen; (f) bourbon whiskey; (g) helium gas; (h) clear water pumped from a deep aquifer

The U.S. quarter has a mass of 5.67 g and is approximately 1.55 mm thick. (a) How many quarters would have to be stacked to reach 575 ft, the height of the Washington Monument? (b) How much would this stack weigh? (c) How much money would this stack contain? (d) The U.S. National Debt Clock showed the outstanding public debt to be $16,213,166,914,811 on October 28, 2012. How many stacks like the one described would be necessary to pay off this debt?

In the United States, water used for irrigation is measured in acre-feet. An acre-foot of water covers an acre to a depth of exactly 1 ft. An acre is 4840 yd2. An acre-foot is enough water to supply two typical households for 1.00 yr. (a) If desalinated water costs $1950 per acre-foot, how much does desalinated water cost per liter? (b) How much would it cost one household per day if it were the only source of water?

By using estimation techniques, determine which of the following is the heaviest and which is the lightest: a 5-lb bag of potatoes, a 5-kg bag of sugar, or 1 gal of water (density = 1.0 g/mL).

Suppose you decide to define your own temperature scale with units of O, using the freezing point 113 °C2 and boiling point 1360 °C2 of oleic acid, the main component of olive oil. If you set the freezing point of oleic acid as 0 °O and the boiling point as 100 °O, what is the freezing point of water on this new scale?

The liquid substances mercury (density = 13.6 g/mL), water (1.00 g/mL), and cyclohexane (0.778 g/mL) do not form a solution when mixed but separate in distinct layers. Sketch how the liquids would position themselves in a test tube.

Two spheres of equal volume are placed on the scales as shown. Which one is more dense?

Water has a density of 0.997 g/cm3 at 25 °C; ice has a density of 0.917 g/cm3 at -10 °C. (a) If a soft-drink bottle whose volume is 1.50 L is completely filled with water and then frozen to -10 °C, what volume does the ice occupy? (b) Can the ice be contained within the bottle?

A 32.65-g sample of a solid is placed in a flask. Toluene, in which the solid is insoluble, is added to the flask so that the total volume of solid and liquid together is 50.00 mL. The solid and toluene together weigh 58.58 g. The density of toluene at the temperature of the experiment is 0.864 g/mL. What is the density of the solid?

A thief plans to steal a gold sphere with a radius of 28.9 cm from a museum. If the gold has a density of 19.3 g/cm3, what is the mass of the sphere in pounds? [The volume of a sphere is V = (4/3)?r3.] Is the thief likely to be able to walk off with the gold sphere unassisted?

Automobile batteries contain sulfuric acid, which is commonly referred to as “battery acid.” Calculate the number of grams of sulfuric acid in 1.00 gal of battery acid if the solution has a density of 1.28 g/mL and is 38.1% sulfuric acid by mass.

A 40-lb container of peat moss measures 14 20 30 in. A 40-lb container of topsoil has a volume of 1.9 gal. (a) Calculate the average densities of peat moss and topsoil in units of g/cm3. Would it be correct to say that peat moss is “lighter” than topsoil? (b) How many bags of peat moss are needed to cover an area measuring 15.0 ft 20.0 ft to a depth of 3.0 in.?

A package of aluminum foil contains 50 ft2 of foil, which weighs approximately 8.0 oz. Aluminum has a density of 2.70 g/cm3. What is the approximate thickness of the foil in millimeters?

The total rate at which power is used by humans worldwide is approximately 15 TW (terawatts). The solar flux averaged over the sunlit half of Earth is 680 W/m2 (assuming no clouds). The area of Earth’s disc as seen from the Sun is 1.28 1014 m2. The surface area of Earth is approximately 197,000,000 square miles. How much of Earth’s surface would we need to cover with solar energy collectors to power the planet for use by all humans? Assume that the solar energy collectors can convert only 10% of the available sunlight into useful power.

In 2005, J. Robin Warren and Barry J. Marshall shared the Nobel Prize in Medicine for discovering the bacterium Helicobacter pylori and for establishing experimental proof that it plays a major role in gastritis and peptic ulcer disease. The story began when Warren, a pathologist, noticed that bacilli were associated with the tissues taken from patients suffering from ulcers. Look up the history of this case and describe Warren’s first hypothesis. What sorts of evidence did it take to create a credible theory based on it?

A 25.0-cm-long cylindrical glass tube, sealed at one end, is filled with ethanol. The mass of ethanol needed to fill the tube is found to be 45.23 g. The density of ethanol is 0.789 g/mL. Calculate the inner diameter of the tube in centimeters.

Gold is alloyed (mixed) with other metals to increase its hardness in making jewelry. (a) Consider a piece of gold jewelry that weighs 9.85 g and has a volume of 0.675 cm3. The jewelry contains only gold and silver, which have densities of 19.3 and 10.5 g/cm3, respectively. If the total volume of the jewelry is the sum of the volumes of the gold and silver that it contains, calculate the percentage of gold (by mass) in the jewelry. (b) The relative amount of gold in an alloy is commonly expressed in units of carats. Pure gold is 24 carat, and the percentage of gold in an alloy is given as a percentage of this value. For example, an alloy that is 50% gold is 12 carat. State the purity of the gold jewelry in carats.

Paper chromatography is a simple but reliable method for separating a mixture into its constituent substances. You have a mixture of two vegetable dyes, one red and one blue, that you are trying to separate. You try two different chromatography procedures and achieve the separations shown in the figure. Which procedure worked better? Can you suggest a method to quantify how good or poor the separation was?

Judge the following statements as true or false. If you believe a statement to be false, provide a corrected version. (a) Air and water are both elements. (b) All mixtures contain at least one element and one compound. (c) Compounds can be decomposed into two or more other substances; elements cannot. (d) Elements can exist in any of the three states of matter. (e) When yellow stains in a kitchen sink are treated with bleach water, the disappearance of the stains is due to a physical change. (f) A hypothesis is more weakly supported by experimental evidence than a theory. (g) The number 0.0033 has more significant figures than 0.033. (h) Conversion factors used in converting units always have a numerical value of one. (i) Compounds always contain at least two different elements.

You are assigned the task of separating a desired granular material with a density of 3.62 g/cm3 from an undesired granular material that has a density of 2.04 g/cm3. You want to do this by shaking the mixture in a liquid in which the heavier material will fall to the bottom and the lighter material will float. A solid will float on any liquid that is more dense. Using an Internet-based source or a handbook of chemistry, find the densities of the following substances: carbon tetrachloride, hexane, benzene, and diiodomethane. Which of these liquids will serve your purpose, assuming no chemical interaction takes place between the liquid and the solids?

In 2009, a team from Northwestern University and Western Washington University reported the preparation of a new “spongy” material composed of nickel, molybdenum, and sulfur that excels at removing mercury from water. The density of this new material is 0.20 g/cm3, and its surface area is 1242 m2 per gram of material. (a) Calculate the volume of a 10.0-mg sample of this material. (b) Calculate the surface area for a 10.0-mg sample of this material. (c) A 10.0-mL sample of contaminated water had 7.748 mg of mercury in it. After treatment with 10.0 mg of the new spongy material, 0.001 mg of mercury remained in the contaminated water. What percentage of the mercury was removed from the water? (d) What is the final mass of the spongy material after the exposure to mercury?

Species that have the same number of electrons are described as isoelectronic. What +2 ion is isoelectronic with Na+? What ?2 ion?

Which of the following ions possess a noble gas electron configuration? (a) K+ (b) He+ (c) H? (d) O? (e) F? (f) Ca2+

What is the electron configuration of C+? Of C?? Does either one of these ions have a noble gas (closed-shell) electron configuration?

Write Lewis formulas, including unshared pairs, for each of the following. Carbon has four bonds in each compound. (a) Propane (C3H8) (b) Methanol (CH4O) (c) Methyl fluoride (CH3F) (d) Ethyl fluoride (C2H5F)

All of the hydrogens are bonded to carbon in both of the following. Write a Lewis formula that satisfies the octet rule for each. (a) Formaldehyde \(\left(\mathrm{CH}_{2} \mathrm{O}\right)\) (b) Hydrogen cyanide (HCN) Text Transcription: CH_2 O

In which of the compounds CH4, NH3, H2O, SiH4, or H2S is \(\delta+\) for hydrogen the greatest? In which one does hydrogen bear a partial negative charge? Text Transcription: delta+

Indicate the direction of the dipole for the following bonds using the symbol and \(\delta+\), \(\delta-\) notation. H ? O H ? N C ? O C = O C ? N C = N \(\mathrm{C} \equiv \mathrm{N}\) Text Transcription: delta+ delta- C equiv N

Why is the formula shown for nitromethane incorrect?

The following inorganic species will be encountered in this text. Calculate the formal charge on each of the atoms in the Lewis formulas given.

Calculate the formal charge on each nitrogen in the following Lewis formula (azide ion) and the net charge on the species. \(: \ddot{N}=N=\ddot{N}:\) Text Transcription: : ddotN=N=ddotN :

Write structural formulas for all the constitutional isomers that have the given molecular formula. (a) C2H7N (b) C3H7Cl (c) C3H8O

Nitrosomethane and formaldoxime both have the molecular formula CH3NO and the connectivity CNO. All of the hydrogens are bonded to carbon in nitrosomethane. In formaldoxime, two of the hydrogens are bonded to carbon and one to oxygen. Write Lewis formulas for (a) nitrosomethane and (b) formaldoxime that satisfy the octet rule and are free of charge separation.

Expand the bond-line formulas of the amino acid cysteine and the neurotransmitter serotonin to show all the unshared electron pairs. Molecular formulas of organic compounds are customarily presented in the fashion CaHbXcYd. Carbon and hydrogen are cited first, followed by the other atoms in alphabetical order. What are the molecular formulas of cysteine and serotonin?

All of the bonds in the carbonate ion (CO32?) are between C and O. Write Lewis formulas for the major resonance contributors, and use curved arrows to show their relationship. Apply the resonance concept to explain why all of the C ? O bond distances in carbonate are equal.

Write the resonance structure obtained by moving electrons as indicated by the curved arrows. Compare the stabilities of the two Lewis formulas according to the guidelines in Table 1.6. Are the two structures equally stable, or is one more stable than the other? Why?

Of the four structural formulas shown, three are permissible and one is not. Which one is not a permissible structure? Why?

Sodium borohydride, NaBH4, has an ionic bond between Na+ and the anion BH4?. What are the H ? B ? H angles in borohydride anion?

Specify the shape of the following:

Which of the following compounds would you expect to have a dipole moment? If the molecule has a dipole moment, specifying its direction. (a) BF3 (b) H2O (c) CH4 (d) CH3Cl (e) CH2O (f) HCN

Using the curved arrow to guide your reasoning, show the products of the following dissociations. Include formal charges and unshared electron pairs. Check your answers to ensure that charge is conserved.

Reactions of the type shown are an important part of Chapter 21. Follow the arrows to predict the products. Show formal charges and include all unshared electron pairs.

Write an equation for proton transfer from hydrogen chloride (HCl) to (a) Ammonia (:NH3) (b) Trimethylamine [(CH3)3N:] Identify the acid, base, conjugate acid, and conjugate base and use curved arrows to track electron movement.

Potassium hydride (KH) is a source of the strongly basic hydride ion (:H?). Using curved arrows to track electron movement, write an equation for the reaction of hydride ions with water. What is the conjugate acid of hydride ions?

Salicylic acid, the starting material for the preparation of aspirin, has a Ka of 1.06 × 10?3. What is its pKa?

Hydrogen cyanide (HCN) has a pKa of 9.1. What is its Ka?

Which is the stronger base in each of the following pairs? (Note: This information will prove useful when you get to Chapter 9.) (a) Sodium ethoxide (NaOCH2CH3) or sodium amide (NaNH2) (b) Sodium acetylide \((\mathrm{NaC} \equiv \mathrm{CH}\) or sodium amide (NaNH2) (c) Sodium acetylide \((\mathrm{NaC} \equiv \mathrm{CH}\) or sodium ethoxide (NaOCH2CH3) Text Transcription: (NaC equiv CH)

Which is the stronger acid, H2O or H2S? Which is the stronger base, HO? or HS?? Check your predictions against the data in Table 1.8.

Try to do this problem without consulting Table 1.8.

Which is a stronger base, ethoxide

Show by writing appropriate resonance structures that the two compounds shown form the same conjugate base on ionization. Which atom in the conjugate base, O or S, bears the greater share of negative charge?

Rank the following in order of decreasing concentration in a solution prepared by dissolving 1.0 mol of sulfuric acid in enough water to give 1.0 L of solution. (It is not necessary to do any calculations.) H2SO4, HSO4?, SO42?, H3O+

Verify that the position of equilibrium for the reaction between phenol and hydroxide ion lies to the right by comparing the pKa of the acid on the left to the acid on the right. Which acid is stronger? Do the same for the reaction of phenol with hydrogen carbonate ion.

Write an equation for the Lewis acid/Lewis base reaction between boron trifluoride and each of the following. Use curved arrows to track the flow of electrons and show formal charges if present. (a) Fluoride ion (b) Dimethyl sulfide [(CH3)2S] (c) Trimethylamine [(CH3)3N]

Write a Lewis formula for each of the following organic molecules: (a) C2H3Cl (vinyl chloride: starting material for the preparation of PVC plastics) (b) C2HBrClF3 (halothane: a nonflammable inhalation anesthetic; all three fluorines are bonded to the same carbon) (c) C2Cl2F4 (Freon 114: formerly used as a refrigerant and as an aerosol propellant; each carbon bears one chlorine)

Write structural formulas for all the constitutionally isomeric compounds having the given molecular formula. (a) C4H10 (b) C5H12 (c) C2H4Cl2 (d) C4H9Br (e) C3H9N

Write structural formulas for all the constitutional isomers of (a) C3H8 (b) C3H6 (c) C3H4

Write structural formulas for all the constitutional isomers of molecular formula C3H6O that contain (a) Only single bonds (b) One double bond

Expand the following structural representations so as to more clearly show all the atoms and any unshared electron pairs. What are their molecular formulas? Are any of them isomers?

Each of the following species will be encountered at some point in this text. They all have the same number of electrons binding the same number of atoms and the same arrangement of bonds; they are isoelectronic. Specify which atoms, if any, bear a formal charge in the Lewis formula given and the net charge for each species. (a) \(: \mathrm{N} \equiv \mathrm{N}:\) (b) \(: \mathrm{C} \equiv \mathrm{N}:\) (c) \(: \mathrm{C} \equiv \mathrm{C}:\) (d) \(: \mathrm{C} \equiv \mathrm{C}:\) (e) \(: \mathrm{C} \equiv \mathrm{O}:\) Text Transcription: : N equiv N : : C equiv N : : C equiv C : : C equiv C : : C equiv O :

Consider Lewis formulas A, B, and C: (a) Are A, B, and C constitutional isomers, or are they resonance contributors? (b) Which has a negatively charged carbon? (c) Which has a positively charged carbon? (d) Which has a positively charged nitrogen? (e) Which has a negatively charged nitrogen? (f) What is the net charge on each? (g) Which is a more stable structure, A or B? Why? (h) Which is a more stable structure, B or C? Why? (i) What is the CNN geometry in each according to VSEPR?

In each of the following pairs, determine whether the two represent resonance contributors of a single species or depict different substances. If two structures are not resonance contributors, explain why.

(a) Which one of the following is not a permissible contributing structure? Why? (b) Rank the three remaining structures in order of their contribution to the resonance hybrid. Explain your reasoning. (c) Using curved arrows, show the electron movement that connects the three resonance contributors.

Of two possible structures A and B for the conjugate acid of guanidine, the more stable is the one that is better stabilized by electron delocalization. Which one is it? Write resonance structures showing this electron delocalization.

Write a more stable contributing structure for each of the following. Use curved arrows to show how to transform the original Lewis formula to the new one. Be sure to specify formal charges, if any.

For each of the following molecules that contain polar covalent bonds, indicate the positive and negative ends of the dipole, using the symbol \(\longmapsto\). Refer to Table 1.3 as needed. (a) HCl (b) HI (c) \(\mathrm{H_2O}\) (d) HOCl Text Transcription: \longmapsto \mathrm{H_2O}

Which compound in each of the following pairs would you expect to have the greater dipole moment \(\mu\)? Why? (a) HF or HCl (b) HF or BF3 (c) (CH3)3CH or (CH3)3CCl (d) CHCl3 or CCl3F (e) CH3NH2 or CH3OH (f) CH3NH2 or CH3NO2 Text Transcription: mu

With a pKa of 11.6, hydrogen peroxide is a stronger acid than water. Why?

The structure of montelukast, an antiasthma drug, is shown here. (a) Use Table 1.8 to identify the most acidic and most basic sites in the molecule. (Although you won’t find an exact match in structure, make a prediction based on analogy with similar groups in simpler molecules.) (b) Write the structure of the product formed by treating montelukast with one equivalent of sodium hydroxide. (c) Write the structure of the product formed by treating montelukast with one equivalent of HCl.

(a) One acid has a pKa of 2, the other has a pKa of 8. What is the ratio of their Ka’s? (b) Two acids differ by a factor of 10,000 in their Ka’s. If the pKa of the weaker acid is 5, what is the pKa of the stronger acid?

Calculate Ka for each of the following acids, given its pKa. Rank the compounds in order of decreasing acidity.

Rank the following in order of decreasing acidity. Although none of these specific structures appear in Table 1.8, you can use analogous structures in the table to guide your reasoning.

Rank the following in order of decreasing basicity. As in the preceding problem, Table 1.8 should prove helpful.

Consider 1.0 M aqueous solutions of each of the following. Which solution is more basic? (a) Sodium cyanide (NaCN) or sodium fluoride (NaF) (c) Sodium sulfate (Na2SO4) or sodium methanethiolate (NaSCH3)

Write an equation for the Brønsted–Lowry acid–base reaction that occurs when each of the following acids reacts with water. Show all unshared electron pairs and formal charges, and use curved arrows to track electron movement.

Write an equation for the Brønsted–Lowry acid–base reaction that occurs when each of the following bases reacts with water. Show all unshared electron pairs and formal charges, and use curved arrows to track electron movement.

All of the substances shown in the following acid–base reactions are found in Table 1.8, and the equilibrium lies to the right in each case. Following the curved arrows, complete each equation to show the products formed. Identify the acid, base, conjugate acid, and conjugate base. Calculate the equilibrium constant for each reaction.

Each of the following acid–base reactions involves substances found in Table 1.8. Use the pKa data in the table to help you predict the products of the reactions. Use curved arrows to show electron flow. Predict whether the equilibrium lies to the left or to the right and calculate the equilibrium constant for each reaction.

With a pKa of 1.2, squaric acid is unusually acidic for a compound containing only C, H, and O. Write a Lewis formula for the conjugate base of squaric acid and, using curved arrows, show how the negative charge is shared by two oxygens.

What are the products of the following reaction based on the electron flow represented by the curved arrows? Which compound is the Lewis acid? Which is the Lewis base?

Lewis formulas are the major means by which structural information is communicated in organic chemistry. These structural formulas show the atoms, bonds, location of unshared pairs, and formal charges. Two or more Lewis formulas, differing only in the placement of electrons, can often be written for a single compound. In such cases the separate structures represented by the Lewis formulas are said to be in resonance, and the true electron distribution is a hybrid of the electron distributions of the contributing structures. The amide function is an important structural unit in peptides and proteins. Formamide, represented by the Lewis structure shown, is the simplest amide. It is a planar molecule with a dipole moment of 3.7 D. Lewis structures I–IV represent species that bear some relationship to the Lewis structure for formamide. Formamide is a planar molecule. According to VSEPR, does the structural formula given for formamide satisfy this requirement? A. Yes B. No

Lewis formulas are the major means by which structural information is communicated in organic chemistry. These structural formulas show the atoms, bonds, location of unshared pairs, and formal charges. Two or more Lewis formulas, differing only in the placement of electrons, can often be written for a single compound. In such cases the separate structures represented by the Lewis formulas are said to be in resonance, and the true electron distribution is a hybrid of the electron distributions of the contributing structures. The amide function is an important structural unit in peptides and proteins. Formamide, represented by the Lewis structure shown, is the simplest amide. It is a planar molecule with a dipole moment of 3.7 D. Lewis structures I–IV represent species that bear some relationship to the Lewis structure for formamide. Which Lewis formula is both planar according to VSEPR and a resonance contributor of formamide? A. I B. II C. III D. IV

Lewis formulas are the major means by which structural information is communicated in organic chemistry. These structural formulas show the atoms, bonds, location of unshared pairs, and formal charges. Two or more Lewis formulas, differing only in the placement of electrons, can often be written for a single compound. In such cases the separate structures represented by the Lewis formulas are said to be in resonance, and the true electron distribution is a hybrid of the electron distributions of the contributing structures. The amide function is an important structural unit in peptides and proteins. Formamide, represented by the Lewis structure shown, is the simplest amide. It is a planar molecule with a dipole moment of 3.7 D. Lewis structures I–IV represent species that bear some relationship to the Lewis structure for formamide. According to VSEPR, which Lewis formula has a pyramidal arrangement of bonds to nitrogen? A. I B. II C. III D. IV

Lewis formulas are the major means by which structural information is communicated in organic chemistry. These structural formulas show the atoms, bonds, location of unshared pairs, and formal charges. Two or more Lewis formulas, differing only in the placement of electrons, can often be written for a single compound. In such cases the separate structures represented by the Lewis formulas are said to be in resonance, and the true electron distribution is a hybrid of the electron distributions of the contributing structures. The amide function is an important structural unit in peptides and proteins. Formamide, represented by the Lewis structure shown, is the simplest amide. It is a planar molecule with a dipole moment of 3.7 D. Lewis structures I–IV represent species that bear some relationship to the Lewis structure for formamide. Which Lewis formula is a constitutional isomer of formamide? A. I B. II C. III D. IV

Lewis formulas are the major means by which structural information is communicated in organic chemistry. These structural formulas show the atoms, bonds, location of unshared pairs, and formal charges. Two or more Lewis formulas, differing only in the placement of electrons, can often be written for a single compound. In such cases the separate structures represented by the Lewis formulas are said to be in resonance, and the true electron distribution is a hybrid of the electron distributions of the contributing structures. The amide function is an important structural unit in peptides and proteins. Formamide, represented by the Lewis structure shown, is the simplest amide. It is a planar molecule with a dipole moment of 3.7 D. Lewis structures I–IV represent species that bear some relationship to the Lewis structure for formamide. Which Lewis formula is a conjugate acid of formamide? A. I B. II C. III D. IV

Lewis formulas are the major means by which structural information is communicated in organic chemistry. These structural formulas show the atoms, bonds, location of unshared pairs, and formal charges. Two or more Lewis formulas, differing only in the placement of electrons, can often be written for a single compound. In such cases the separate structures represented by the Lewis formulas are said to be in resonance, and the true electron distribution is a hybrid of the electron distributions of the contributing structures. The amide function is an important structural unit in peptides and proteins. Formamide, represented by the Lewis structure shown, is the simplest amide. It is a planar molecule with a dipole moment of 3.7 D. Lewis structures I–IV represent species that bear some relationship to the Lewis structure for formamide. Which Lewis formula is a conjugate base of formamide? A. I B. II C. III D. IV

How many electrons does carbon have? How many are valence electrons? What third-row element has the same number of valence electrons as carbon?

Referring to the periodic table as needed, write electron configurations for all the elements in the third period.

Listing the atoms in the order CHNOP, what is the molecular formula of ATP? (You can check your answer by entering adenosine triphosphate in your web browser.) Show the location of all its unshared electron pairs. How many are there?

Write equations, including curved arrows, describing the reverse reactions of Problem 1.23.

Hypochlorous and hypobromous acids (HOCl and HOBr) are weak acids. Write chemical equations for the ionization of each in water and predict which one is the stronger acid.

What is the average formal charge on each oxygen in nitrate ion?

What is the equilibrium constant for the following acid–base reactions? (a) ammonia and acetic acid (b) fluoride ion and acetic acid (c) ethanol and hydrobromic acid

The connectivity of carbon oxysulfide is OCS. (a) Write a Lewis formula for carbon oxysulfide that satisfies the octet rule. (b) What is molecular geometry according to VSEPR? (c) Does carbon oxysulfide have a dipole moment? If so, what is its direction?

The compounds FCl and ICl have dipole moments ? that are similar in magnitude (0.9 and 0.7 D, respectively) but opposite in direction. In one compound, chlorine is the positive end of the dipole; in the other it is the negative end. Specify the direction of the dipole moment in each compound, and explain your reasoning.