Week 2 Notes
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This 5 page Class Notes was uploaded by Andrew Notetaker on Thursday September 1, 2016. The Class Notes belongs to CHM 113 at Arizona State University taught by Cabirac in Fall 2016. Since its upload, it has received 19 views. For similar materials see General chemistry 1 in Science at Arizona State University.
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Date Created: 09/01/16
Chapter 1 8-24 & 8-29 Wednesday, August 24, 2016 3:04 PM 1.1 Si sessions Matter is anything that has mass and occupies space. Tonight 5:00-5:50 in WXLR A118 Atoms are the building blocks of matter. Each element is made of the same kind of atom. Friday 10:00am-10:50MSHAL States of Matter F101 Substances can exist in the solid, liquid or gas state. Solids: • Rigid • Cannot be squashed or compressed • Fixed shape and volume Liquids: • Closely packed but not as much as solids • Not rigid • Cannot be squashed or compressed • No fixed shape • Fixed volume Gases: • Not closely packed • Not rigid • Can be squashed and compressed • No fixed shape or volume • Fill the container they are in 1.2 Classifications of Matter Any substance can exist in the solid, liquid or gas state. Pure Substances: Elements Compounds Molecules Elements, if not mixed with other elements, are considered pure substances and are composed of only one type of atom Ex: • Iron metal (Fe) • Sulfur Elements and compounds (and molecules) are considered pure substances, have definite compositions and a set of properties that are unique. KNOW: The element names and symbols for the first 36 elements. Compounds are combinations of atoms of more than one type of element. Ex: • Sodium Chloride (NaCl) • Ammonia (NH ) 3 • Water Compounds are combinations of atoms of more than one type of element. Molecules: Molecules are groups of atoms (two or more) bonded chemically Not all molecules are compounds: H2is not a compound NH 3s a compound Homogenous Mixtures (solutions) • Constant composition throughout Examples: air, salt water, metal alloys Heterogeneous Mixtures (solutions) Not constant composition throughout Examples: cookies Mixtures: Two or more pure substances that are combined physically but not chemically. 1.3 Properties of Matter CHM 113 Lecture Page 1 1.3 Properties of Matter Physical properties: Can be observed without changing a substance into another substance • Boiling point, density, mass, volume Chemical Properties: Can only be observed when matter undergoes a chemical change • Iron reacts with oxygen to form iron oxide, sodium reacts with water to give off hydrogen gas Identify the following as chemical or physical properties: Melting point of aluminum Ability of nitric acid to dissolve copper Density of mercury Boiling point of water Flammability of hydrogen Mixtures can have properties distinct from any of the individual substances making up the mixtures! Intensive Properties Are independent of the amount of the substance that is present (useful for identifying substances) Physical changes Changes in matter that do not change the composition of a substance Changes of state, temperature, volume Chemical changes Chemical changes result in new substances Changes of state (phase changes) Rusting 2Na + 2l --> 2NaCl Chemical change Evidence: Gas generated (Bubbling) Heat evolved/absorbed Color Change 1.4 Units of Measurement Measurements Used to communicatequantitative information Consists of a number and an appropriate unit Ex: 1.5 yards SI Units A different base unit is used for each quantity Mass Kilogram Kg Length Meter M Time Second S or sec Temperature Kelvin K Amount of substance Mole Mol Metric units are based on powers of 10 Giga G 10^9 Mega M 10^6 Kilo K 10^3 Centi C 10^-2 Milli M 10^-3 Micro U 10^-6 Nano N 10^-9 Pico P 10^-12 CHM 113 Lecture Page 2 What is the size of an atom? Of the earth? Exponential (Scientific) Notation to express small and large numbers Radius of a sodium atom= 1.54 x 10^-10m = 154 pm Monday, August 29th, 2016 By definition temperature is a measure of the average kinetic energy of the particles in a sample. Temperature Relationships Kelvin(k)= C +273.15 C=5/9 (F-32) F=5/9C+32 Derived SI Units: Volume and Density Volume: length x length x length 1cm =1mL Density is an intensive physical property of a substance of a substance. It has units (g/mL) that are derived from the units from mass and volume. Carbon dioxide gas is more dense than helium gas. Why? O=C=O has greater mass than He Water is more dense than ice therefore ice floats on water. 1.5 Uncertainty in Measurement Exact numbers Inexact numbers- Numbers obtained by measurement Accuracy- refers to the proximity of a measurementto the true value of a quantity Precision- refers to the proximity of several measurements together A measured quantity expressed as a number will have digits that are certain plus one uncertain digit (the rightmost digit) 1. All nonzero digits are significant. 2. Zeroes between two significant figures are themselves significant. 3. Zeroes at the beginning of a number are never significant 4. Zeros at the end of a number are significant if a decimal point is written in the number Measured value # of SF 2.456 4 1003.2 5 1.0300 6 .0000402 3 230000 2 1.230 x 10-8 4 Adding and Subtracting The final answer iexpressed with the same number of decimal places as the measurement with the fewest number of Sig. figs. Multiplying and Dividing The final answer is expressed with the same number of sig. figs. as the measurement with the fewest number of Sig. figs. Conversion factors are often exact numbers and are not measurements. Examples 12 inches = 1 foot 1000 mm = 1 meter 60 sec = 1 minute Sig. figs. DO NOT APPLY TO DIRECT MEASUREMENTS CHM 113 Lecture Page 3 Sig. figs. DO NOT APPLY TO DIRECT MEASUREMENTS 1.6 Dimensional Analysis Most commonly,dimensional analysis utilizes conversion factors. Use conversion factors as a ratio. Convert 7.5 cm to inches More examples: 45 sec to minutes Convert 416 nm to meters Convert 8.00 m to inches • Convert m to cm Convert cm to in A piece of aluminum foil is cut to a length of 5.00cm and a width of 4.00cm. Density is 2.70g/cm and the mass is measured as 0.154g What is the thickness? Conversions involving volumes 3 3 If the volume of an object is reported as 5.0ft , what is the volume in cubic meters (m )? CHM 113 Lecture Page 4 CHM 113 Lecture Page 5
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