It is possible to tow icebergs to coastal cities as a

What defines a material as being a mixture?

How can the components of a mixture be separated from one another?

How does distillation separate the components of a mixture?

Why isnt it practical to have a macroscopic sample that is 100% pure?

How is a solution different from a suspension?

How can a solution be separated from a suspension?

What happens to the volume of a sugar solution as more sugar is dissolved in it?

Distinguish between a solute and a solvent.

What does it mean to say that a solution is concentrated?

Is concentration typically given with the volume of solvent or the volume of solution?

Why does the solubility of a gas solute in a liquid solvent decrease with increasing temperature?

Why do sugar crystals dissolve faster when crushed?

Is sugar a polar or nonpolar substance?

Which portion of a soap molecule is nonpolar?

What is the difference between a soap and a detergent?

What component of hard water makes it hard?

Why are soap molecules so attracted to calcium and magnesium ions?

Why is treated water sprayed into the air before it is piped to users?

What are two ways in which people disinfect water in areas where municipal treatment facilities are not available?

What naturally occurring element has been contaminating the water supply of Bangladesh?

Why can wastewater treatment requirements in Hawaii be less stringent than those in most locations on the U.S. mainland?

What is the first step in treating raw sewage?

Why dont all municipalities require third-level treatment of wastewater?

To see the gases dissolved in your water, fill a clean cooking pot with water and let it stand at room temperature for several hours. Note the tiny bubbles that adhere to the inner sides of the pot. Where did these tiny bubbles come from? What do you suppose they contain? For further experimentation, repeat this activity in two pots set side by side. In one pot, use warm water from the kitchen faucet. In the second pot, use boiled water that has cooled down to the same temperature.

Put on your safety glasses and add several cups of tap water to a cooking pot. Boil the water to dryness. (Turn off the burner before the water is all gone. The heat from the pot will finish the evaporation. Watch out for splattering!) Examine the resulting residue by scraping it off with a knife. These are the solids you ingest with every glass of water you drink.

Black ink contains pigments of many different colors. Acting together, these pigments absorb all the frequencies of visible light. Because no light is reflected, the ink appears black. We can use molecular attractions to separate the components of black ink through a technique that is called paper chromatography. What you need: black felt-tip pen or black water-soluble marker; piece of porous paper, such as paper towel, table napkin, or coffee filter; solvent, such as water, acetone (fingernailpolish remover), rubbing alcohol, or white vinegar Procedure: 1. Place a concentrated dot of ink at the center of the piece of porous paper. 2. Carefully place one drop of solvent on top of the dot, and watch the ink spread radially with the solvent. Because the different components of the ink have different affinities for the solvent (based on the attractions between component molecules and solvent molecules), they travel with the solvent at different rates. 3. Just after the drop of solvent is completely absorbed, add a second drop at the same location as the first one, then a third, and so on until the ink components have separated to your satisfaction.Paper chromatography was originally developed to separate plant pigments from one another. The separated pigments had different colors, which is how this technique got its namechroma is Latin for color. Mixtures need not be colored, however, to be separable by chromatography. All thats required is that the components have distinguishable affinities for the moving solvent and the stationary medium, such as paper, through which the solvent will pass.

Just because a solid dissolves in a liquid doesnt mean the solid no longer occupies space. Fill a glass to its brim with the warm water, and then carefully pour all the water into the larger container. Add a couple tablespoons of sugar to the empty glass. Return half of the warm water to the glass and stir to dissolve all the sugar. Return the remaining water, and as you get close to the top, ask a friend to predict whether the water level will be lower than, about the same as, or higher than before. If your friend doesnt understand the result, ask him or her what would happen if you had added the sugar to the glass when the glass was full of water.

You can build a relatively inefficient but fun-to-watch distiller at home. Avoid the steam produced in this activity steam burns can be particularly harmful. Step 1: Fill a cooking pot to a depth of about 1 cm. Add food coloring or some salt or both. Step 2: Place a heavy ceramic coffee mug in the center of the pot. The height of the mug should be at least 1 inch below the height of the pot. Step 3: Lay plastic wrap loosely across the top of the pot and secure it with a rubber band. The seal should not be airtightleave two of the edges open to prevent a buildup of pressure. Trim away excess plastic wrap. Place an ice cube at the center. Step 4: Put on safety glasses and turn the burner on low to bring the water to a low boil. Look for signs of cloud formation below the ice cube. Once the water is boiling, the mug may jostle. Step 5: Turn off the heat. Remove the melted ice with a sponge. Why isnt the solute carried over into the mug? How much distilled water are you able to collect per ice cube? How might you modify your distiller so that it works well using only sunlight?

Heres a quick recipe for rock candy. In a cooking pot make a hot saturated solution of sugar in water. Start by mixing sugar and water in a 2:1 ratio by volume. Add more sugar or water as necessary to obtain a clear runny syrup. Let cool for 10 minutes. Roll a wet skewer stick or weight (such as a metal nut) attached to a string in some granulated sugar. Pour the warm sugar syrup into a jar. Submerge the skewer or weight in the sugar syrup. For support, consider setting a clothespin or a pencil across the rim. Cover the top and store in a cool place. The longer you wait, the larger the crystals will be.

Assume the total number of molecules in a sample of liquid is about 3 million trillion. One million trillion of these are molecules of some poison, while 2 million trillion are water molecules. What percentage of all the molecules in the glass are water?

Assume the total number of molecules in a glass of liquid is about 1,000,000 million trillion. One million trillion of these are molecules of some poison, while 999,999 million trillion of these are water molecules. What percentage of all the molecules in the glass are water?

You drink a small glass of water that is 99.9999% pure water and 0.0001% some poison. Assume the glass contains about a 1,000,000 million trillion molecules, which is about 30 mL. How many poison molecules did you just drink? Should you be concerned?

How much sodium chloride, in grams, is needed to make 15 L of a solution that has a concentration of 3.0 g of sodium chloride per liter of solution?

If water is added to 1 mole of sodium chloride in a flask until the volume of the solution is 1 L, what is the molarity of the solution? What is the molarity when water is added to 2 moles of sodium chloride to make 0.5 L of solution?

A student is told to use 20.0 g of sodium chloride to make an aqueous solution that has a concentration of 10.0 g/L (grams of sodium chloride per liter of solution). Assuming that 20.0 g of sodium chloride has a volume of 7.50 mL, show that she will need about 1.99 L of water to make this solution. In making this solution, should she add the solute to the solvent or the solvent to the solute?

Rank the following solutions in order of increasing concentration. solution A, 0.5 mole of sucrose in 2.0 L of solution; solution B, 1.0 mole of sucrose in 3.0 L of solution; solution C, 1.5 moles of sucrose in 4.0 L of solution.

Rank the compounds in order of increasing solubility in water: CH3CH2OH Ethanol CH3CH2CH2CH2OH Butanol CH3CH2CH2CH2CH2CH2OH Hexanol

List these compounds in order of increasing boiling point: CI4, CBr4, CCl4, CF4.

How might you separate a mixture of sand and salt? How about a mixture of iron and sand?

Mixtures can be separated into their components by taking advantage of differences in the chemical properties of the components. Why might this separation method be less convenient than taking advantage of differences in the physical properties of the components?

Why cant the elements of a compound be separated from one another by physical means?

Many dry cereals are fortified with iron, which is added to the cereal in the form of small iron particles. How might these particles be separated from the cereal?

Classify each of the following as a homogeneous mixture, heterogeneous mixture, element, or compound: (a) table salt, (b) blood, (c) steel, (d) planet Earth.

Some bottled water is now advertised as containing extra quantities of Vitamin O, which is a marketing gimmick for selling oxygen, O2. Might this bottle water actually contain extra quantities of oxygen, O2? How much more O2 than one might find in regular bottled water? How might the amount of oxygen we absorb through our lungs compare to the amount we might absorb through our stomachafter burping?

Classify each of the following as an element, compound, or mixture, and justify your classifications: salt, stainless steel, tap water, sugar, vanilla extract, butter, maple syrup, aluminum, ice, milk, cherry-flavored cough drops.

Which of the boxes above best represents a suspension?

Which of the boxes above best represents a solution?

Which of the boxes above best represents a compound?

Explain why, for these three substances, the solubility in 20C water goes down as the molecules get larger but the boiling point goes up.

The boiling point of 1,4-butanediol is 230C. Would you expect this compound to be soluble or insoluble in roomtemperature water? Explain.

Based on atomic size, which would you expect to be more soluble in water: helium, He, or nitrogen, N2?

If nitrogen, N2, were pumped into your lungs at high pressure, what would happen to its solubility in your blood?

The air a scuba diver breathes is pressurized to counteract the pressure exerted by the water surrounding the divers body. Breathing the high-pressure air causes excessive amounts of nitrogen to dissolve in body fluids, especially the blood. If a diver ascends to the surface too rapidly, the nitrogen bubbles out of the body fluids (much as carbon dioxide bubbles out of a soda immediately after the container is opened). This results in a painful and potentially lethal medical condition known as the bends. Why does breathing a mixture of helium and oxygen rather than air help divers avoid getting the bends?

Account for the observation that ethanol, C2H5OH, dissolves readily in water but dimethyl ether, CH3OCH3, which has the same number and kinds of atoms, does not.

At 10C, which is more concentrated: a saturated solution of sodium nitrate, NaNO3, or a saturated solution of sodium chloride, NaCl? (See Figure 16.20.)

Why is rain or snow called precipitation?

The volume of many liquid solvents expands with increasing temperature. What happens to the concentration of a solution made with such a solvent as the temperature of the solution is increased?

Hydrogen chloride, HCl, is a gas at room temperature. Would you expect this material to be very soluble or not very soluble in water?

Two plastic bottles of fresh seltzer water are opened. Threefourths of the first bottle are poured out for drinking, while only one-fourth of the second bottle is poured. Both bottles are then tightly resealed. The next day they are both reopened, and one is less fizzy. Which one? Why?

Which should weigh more: 100 mL of fresh water or 100 mL of fresh sparkling seltzer water? Why? Which should weigh more: 100 mL of flat seltzer water at 20C or the same 100 mL of flat seltzer water brought to 80C? Why?

Why can 500 mL of fresh water absorb more gaseous carbon dioxide than 500 mL of sugar water at the same temperature?

Would you expect to find more dissolved oxygen in ocean water around the northern latitudes or in ocean water close to the equator? Why?Fatty acid molecules can align to form a barrier called a bilipid layer, shown below. In this schematic, the ionic end of the fatty acid is shown as a circle, and the nonpolar chain is shown as a squiggly line. Use this diagram for Exercises 63 and 64.

Why do nonpolar molecules have a difficult time passing through the bilipid layer? How about polar molecules?

Fatty acid molecules can also align to form a bilipid layer that extends in three-dimensions. Shown below is a crosssection of this structure. This is similar to the micelle shown in Figure 16.23, though notably different because it contains an inner compartment of water. What is this structure called? (Hint: It forms the basis of all life.)

How is it that water and soap are attracted to each other not only by iondipole attraction but also by dipole induced dipole attraction?

A scum forms on the surface of boiling hard water. What is this scum? Why does it form? And why do hot water heaters lose their efficiency quicker in households with hard water?

Calcium and magnesium ions are more attracted to sodium carbonate than to soap. Why?

Phosphate ions, PO4 3-, were once added to detergents to assist in cleaning. What function did they serve? These ions are no longer added to detergents because they cause excessive growth of algae in aquatic habitats that receive the wastewater. What chemical has replaced them?

Cells at the top of a tree have a higher concentration of sugars than cells at the bottom. How might this fact assist a tree in moving water upward from its roots?

Why is flushing a toilet with clean water from a municipal supply about as wasteful as flushing it with bottled water?

What reverses in reverse osmosis?

Why is it significantly less costly to purify fresh water through reverse osmosis than to purify salt water through reverse osmosis?

Some people fear drinking distilled water because they have heard it leaches minerals from the body. Using your knowledge of chemistry, explain why these fears have no basis and how distilled water is in fact very good for drinking.

Many homeowners get their drinking water piped up from wells dug into their property. Sometime this well water smells bad because of trace quantities of the gaseous compound hydrogen sulfide, H2S. How might this odor be removed from water already taken from the tap?

Is the decomposition of food by bacteria in our digestive systems aerobic or anaerobic? What evidence supports your answer? How do composting toilets remove the bad smells of human waste?

Oxygen, O2, dissolves quite well in a class of compounds known as liquid perfluorocarbonsso well that oxygenated perfluorocarbons can be inhaled in a liquid phase, as is demonstrated by the rodent shown below the water-bound goldfish. Do you suppose perfluorocarbon molecules are polar or nonpolar? Why would the rodent drown if it were brought up to the water layer and the goldfish die if they swam down into the perfluorocarbon layer? How might perfluorocarbons be used to clean our lungs or serve as artificial blood? When is it okay to sacrifice the lives of animals for scientific research?

Why are people so willing to buy bottled water when it is so expensive, both financially and environmentally?

It is possible to tow icebergs to coastal cities as a source of fresh water. What obstaclestechnological, social, environmental, and politicaldo you foresee for such an endeavor?

In reference to human nature, Jerome Delli Priscoli, a social scientist with the U.S. Army Corps of Engineers, stated, The thirst for water may be more persuasive than the impulse toward conflict. Do you agree or disagree with his statement? Might our universal need for water be our salvation or our demise? Consider the current water disputes between countries such as Sudan and Egypt or Turkey and Iraq.

Search the Internet to find what major rivers in the world no longer reach the oceans. What impact does beef consumption have on water use? How are these two issues related?