Welcome to AP Chemistry

What is AP Chemistry? l It is several things l Equivalent of 1 year college inorganic chemistry class l A class that will prepare you for a test –May ?? l Hard work l Now on to the details

Rules and Procedures l You know the basic rules but here are a few that are specific for this class l No food drink or gum l LATE WORK l If you forget to bring in your homework, I will accept it ONE day late. l I will not accepted it any later.

Rules and Procedures l MAKE-UP WORK l It is your responsibility to make up all the work you missed. You have the same number of days that you were absent to turn in the missing work. l Pick up any missing work, and notes before or after class. l If you miss a test or quiz, it must be made up outside class.

What you need for class l Paper l Pencil or pen, l Calculator- scientific l Book l Notebook

Internet Ready l Check my web page for notes and updates

Any questions? l Lets get started

Significant figures l Meaningful digits in a MEASUREMENT l Exact numbers are counted, have unlimited significant figures l If it is measured or estimated, it has sig figs. l If not it is exact. l All numbers except zero are significant. l Some zeros are, some aren’t

Which zeroes count? l In between other sig figs does l Before the first number doesn’t l After the last number counts iff l it is after the decimal point l the decimal point is written in l sig figs l sig figs

Doing the math l Multiplication and division, same number of sig figs in answer as the least in the problem l Addition and subtraction, same number of decimal places in answer as least in problem.

More Preliminaries Scientific Method Metric System Uncertainty

Scientific method. l A way of solving problems l Observation- what is seen or measured l Hypothesis- educated guess of why things behave the way they do. (possible explanation) l Experiment- designed to test hypothesis l leads to new observations, l and the cycle goes on

Scientific method. l After many cycles, a broad, generalizable explanation is developed for why things behave the way they do l Theory l Also regular patterns of how things behave the same in different systems emerges l Law l Laws are summaries of observations

Scientific method. l Theories have predictive value. l The true test of a theory is if it can predict new behaviors. l If the prediction is wrong, the theory must be changed. l Theory- why l Law - how

Observations Hypothesis Experiment Law Theory (Model) Prediction Experiment Modify

Metric System l Every measurement has two parts l Number l Scale (unit) l SI system (le Systeme International) based on the metric system l Prefix + base unit l Prefix tells you the power of 10 to multiply by - decimal system -easy conversions

Metric System l Base Units l Mass - kilogram (kg) l Length- meter (m) l Time - second (s) l Temperature- Kelvin (K) l Electric current- ampere (amp, A) l Amount of substance- mole (mol)

Prefixes l giga- G 1,000,000, l mega - M 1,000, l kilo - k 1, l deci-d l centi-c l milli-m l micro-m l nano-n

Deriving the Liter l Liter is defined as the volume of 1 dm 3 l gram is the mass of 1 cm 3

Mass and Weight l Mass is measure of resistance to change in motion l Weight is force of gravity. l Sometimes used interchangeably l Mass can’t change, weight can

Uncertainty l Basis for significant figures l All measurements are uncertain to some degree l Precision- how repeatable l Accuracy- how correct - closeness to true value. l Random error - equal chance of being high or low- addressed by averaging measurements - expected

Uncertainty l Systematic error- same direction each time l Want to avoid this l Better precision implies better accuracy l you can have precision without accuracy l You can’t have accuracy without precision

Dimensional Analysis Using the units to solve problems

Dimensional Analysis l Use conversion factors to change the units l Conversion factors = 1 l 1 foot = 12 inches (equivalence statement) l 12 in = 1 = 1 ft. 1 ft. 12 in l 2 conversion factors l multiply by the one that will give you the correct units in your answer.

Examples l 11 yards = 2 rod l 40 rods = 1 furlong l 8 furlongs = 1 mile l The Kentucky Derby race is 1.25 miles. How long is the race in rods, furlongs, meters, and kilometers? l A marathon race is 26 miles, 385 yards. What is this distance in rods, furlongs, meters, and kilometers?

Examples l Science fiction often uses nautical analogies to describe space travel. If the starship U.S.S. Enterprise is traveling at warp factor 1.71, what is its speed in knots? l Warp 1.71 = 5.00 times the speed of light l speed of light = 3.00 x 10 8 m/s l 1 knot = 2000 yd/h exactly

l Apothecaries (druggists) use the following set of measures in the English system: l 20 grains ap = 1 scruple (exact) l 3 scruples = 1 dram ap (exact) l 8 dram ap = 1 oz. ap (exact) l 1 dram ap = g l 1 oz. ap = ? oz. troy l What is the mass of 1 scruple in grams? Examples

l The speed of light is 3.00 x 10 8 m/s. How far will a beam of light travel in 1.00 ns?

Temperature and Density

Temperature l A measure of the average kinetic energy l Different temperature scales, all are talking about the same height of mercury. l Derive a equation for converting ºF toºC

0ºC 32ºF 0ºC = 32ºF

100ºC212ºF 100ºC = 212ºF 0ºC 32ºF 0ºC = 32ºF

100ºC212ºF 0ºC 32ºF 100ºC = 212ºF 0ºC = 32ºF 100ºC = 180ºF

100ºC212ºF 0ºC 32ºF 100ºC = 212ºF 0ºC = 32ºF 100ºC = 180ºF 1ºC = (180/100)ºF 1ºC = 9/5ºF

ºC ºF

ºC ºF (0,32)= (C 1,F 1 )

ºC ºF (0,32) = (C 1,F 1 ) (120,212) = (C 2,F 2 )

Density l Ratio of mass to volume l D = m/V l Useful for identifying a compound l Useful for predicting weight l An intrinsic property- does not depend on what the material is

Density Problem l An empty container weighs g. Filled with carbon tetrachloride (density 1.53 g/cm 3 ) the container weighs g. What is the volume of the container?

Density Problem lAlA 55.0 gal drum weighs 75.0 lbs. when empty. What will the total mass be when filled with ethanol? density g/cm 3 1 gal = 3.78 L 1 lb = 454 g