Unit 0: Matter, Measurement, and Chemical Equations AP Chemistry

Matter Chapter 1

The Classification of Matter Matter is anything that occupies space and has mass Classified by: State: its physical form (solid, liquid, gas) Composition: its components (elements, compounds, mixtures)

Classification of Matter by Components Pure substance: made up of only one component Elements (i.e. gold) Compounds (i.e. sodium chloride) Mixture: made of two or more components; proportions vary Heterogeneous: composition of mixture varies; can see the parts (i.e. oil and water) Homogeneous: all portions are uniform and have the same composition and properties (i.e. salt water)

Separating Mixtures Decanting—carefully pouring off liquid from a precipitate (Remember doing this in the copper lab??) Distillation—separates homogeneous mixtures of two liquids or a liquid & a dissolved solid

Separating Mixtures (cont.) Gravity Filtration—a heterogeneous mixture of a liquid and solid are poured through filter paper and funnel Vacuum filtration—a vacuum is set up with a sink apparatus to aid the filtration process

Physical vs. Chemical Changes Physical change—alters the state or appearance, not composition i.e. boiling, cutting magnesium Chemical change—alters the composition of matter i.e. rusting nails, burning magnesium

Physical vs. Chemical Properties Physical property—can be observed without changing the chemical composition i.e. odor, taste (!), color, appearance, melting & boiling point, density Chemical property—can be observed by changing the composition (must have a chemical rxn) Flammability, acidity, reactivity

Energy

Energy Energy—the capacity to do work (applying a force over a given distance) Types of energy Kinetic—the motion of an object Potential—the position of an object Thermal—the temperature of an object (technically a type of kinetic energy) Law of Conservation of Energy—cannot be created or destroyed

Units & measurement

Units of Measurement Metric System (meters, liters, etc) English System (inches, pounds, etc.) International System of Units (SI) Used in science

SI Base Units

Dimensional Analysis Used to convert between units using conversion factors Know prefixes and how they are used to give you conversions i.e. 1 liter contains 1000 mL Other Useful temperature conversions:

Significant Figures

Significant Figures Significant figures are all the certain digits and the estimated digit in a measurement. For example, 31.7 mL has three “sig figs”. Two certain digits (the 3 and the 1) One estimated digit (the 7)

Why Significant Figures? “Sig Figs” indicate the quality of instrument you use for your measurements. Electronic balance may give 2.301 g Analytical balance may give 2.30117 g Usually, high precision is indicated by a large number of sig figs. Ex: A measurement of 4.005 L (4 sig figs) is considered more precise than a measurement of 4 L (1 sig fig)

Significant Figures Rules All non-zero digits of a measurement are significant 283.47 g  5 sig figs Zeros written between significant digits are significant 56.06 g  4 sig figs All final zeros past a decimal point are significant 73.00  4 sig figs 7,300  2 sig figs

Significant Figures Rules Zeros written to the left of all nonzero digits are not significant. 0.09 g  1 sig fig Numbers in scientific notation have the same number of sig figs as the portion that’s before the “x 10” part. 4.30 x 105  3 sig figs

Significant Figures in Calculations Multiplication/Division Your answer should have the same number of sig figs as the value with the fewest sig figs in the problem. Ex: 1.220 X 3.4870 = 4.25414  round to 4.254 Because 1.220 has four sig figs

Significant Figures in Calculations Addition/Subtraction Your answer should have the same number of sig figs to the right of the decimal as the value with the fewest decimal places in the problem. Ex: 3.4 + 5.023 = 8.423  round to 8.4 Because 3.4 has one digit to the right of the decimal

Rounding in Multi-Step Calculations ROUND ONLY THE FINAL ANSWER Underlined digits in calculations signify the least significant digit

Scientific Notation

Scientific Notation Scientific Notation is a short way to write very large or very small numbers. It is written as the product of a number between 1 and 10 and a power of 10.

Converting to Scientific Notation Create a number between 1 and 10 by moving the decimal to the left or right. Count the number of spaces the decimal moved to determine the exponent on 10. The exponent is POSITIVE if you moved your decimal to the LEFT The exponent if NEGATIVE if you moved your decimal to the RIGHT

Converting to Scientific Notation Example: 3,346,000,000 = 3.346 x 109 The decimal moved 9 places Example: 0.000952 = 9.52 x 10-4 Exponent = number of decimal places moved to the LEFT Number between 1 and 10 Exponent = number of decimal places moved to the RIGHT Number between 1 and 10

Converting to Standard Notation Move the decimal to the right or left the number of spaces indicated by the exponent Move to the LEFT if exponent is NEGATIVE Move to the RIGHT if exponent is POSITIVE Example: 1.312 x 106 = 1,312,000 Example: 1.312 x 10-6 = 0.000001312

Calculations with Scientific Notation Punch the number (the digit number) into your calculator. Push the EE or EXP button. Do NOT use the x (times) button. Enter the exponent number. Use the +/- button to change its sign. Voila! Treat this number normally in all subsequent calculations. To check yourself, multiply 6.0 x 105 times 4.0 x 103 on your calculator. Your answer should be 2.4 x 109 Instructions for scientific calculator

Calculations with Scientific Notation Punch the number (the digit number) into your calculator. Push 2nd then EE button. Use the - button to indicate sign of exponent (if negative) Enter the exponent number. Voila! Treat this number normally in all subsequent calculations. To check yourself, multiply 6.0 x 105 times 4.0 x 103 on your calculator. Your answer should be 2.4 x 109 **NOTE: you may use the x (times) button and the ^ (carrot) button instead but make sure you put the number in parentheses so your calculator follows correct order of operations. Instructions for graphing calculator

Precision vs. Accuracy Accuracy—how close the measured value is to the actual value Precision—how close a series of measurements are to each other; reproducibility 100 mL beaker gives results +/- 1 mL 100 mL graduated cylinder gives results +/- 0.1 mL

Practice Problems

Practice Problems Classification of Physical/Chemical Changes Burning magnesium Alcohol evaporating Two aqueous solutions are mixed and a yellow solid forms Boiling water Alka Seltzer in water forms gas bubbles

Practice Problems Classification of Physical/Chemical Changes Burning magnesium—chemical Alcohol evaporating—physical Two aqueous solutions are mixed and a yellow solid forms—chemical Boiling water—physical Alka Seltzer in water forms gas bubbles—chemical

Practice Problems Use dimensional analysis to convert between metric units. How many mL are in 5 kL? How many grams are in 7.9 mg?

Practice Problems Use dimensional analysis to convert between metric units. How many mL are in 5 kL? 5,000,000 mL How many grams are in 7.9 mg? 0.0079 g

How many Sig Figs? 5.6009 67,000,000 0.000952 92.140000 6.925 x 108

How many Sig Figs? 5.6009 5 67,000,000 2 0.000952 3 92.140000 8 6.925 x 108 4

Practice Problems Round each of these measurements to three sig figs. 5,907 314.00124 0.003918 67,412

Practice Problems Round each of these measurements to three sig figs. 5,907= 5,910 314.00124= 314 0.003918= 0.00392 67,412= 67,400

Practice Problems Convert the following to Scientific Notation 890,000,000 0.0000605 706,079 Convert the following to standard notation. 8.3 x 10-3 7.902 x 107

Practice Problems Convert the following to Scientific Notation 890,000,000= 8.9 x 108 0.0000605= 6.05 x 10-5 706,079= 7.06079 x 105 Convert the following to standard notation. 8.3 x 10-3 = 0.0083 7.902 x 107 = 79,020,000