Welcome to AP Chemistry

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

Rules and Procedures You know the basic rules but here are a few that are specific for this class. No food, drink, or gum Don’t disrupt. Be respectful of all. Be ready to start when class begins. Refer to the Course Guidelines sheet found on the website and handed out to you. The class website is

Rules and Procedures You are AP ! I will treat you as such as long as you act accordingly. There are resources that it would help to be familiar with. Quizlet Khan Academy or similar More to follow

Rules and Procedures LAB – Because of the importance of safety in the lab, violation of laboratory safety rules and procedures may result in loss of lab privileges. LAB SAFETY (otherwise known as OUR SAFETY) is not taken lightly.

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

Which zeroes count ? In between other significant figures, they DO COUNT Before the first number, they DON’T COUNT After the last non-zero number counts IF it is after the decimal point. (see below) significant figures significant figures

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

More Preliminaries Scientific Method Metric System Uncertainty

Scientific method A way of solving problems Observation - What is seen or measured Hypothesis - Educated guess of why things behave the way they do. (possible explanation) Experiment- Designed to test hypothesis Leads to new observations, and the cycle goes on. See the PPT on the website for more detail.

Scientific method. After many cycles, a broad, general explanation is developed for why things behave the way they do. Theory - Regular patterns of how things behave the same in different systems emerges Law - Laws are essentially theories that have been proven beyond reasonable doubt.

Scientific method. Theories have predictive value. The true test of a theory is if it can predict new behaviors. If the prediction is wrong, the theory must be changed. A key to the Scientific Method is that a Theory is constantly evolving due to more and more experimentation.

Observations Hypothesis Experiment Law Theory (Model) Prediction Experiment Modify

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

Metric System Base Units Mass - kilogram (kg) Length- meter (m) Time - second (s) Temperature- Kelvin (K) Electric current- ampere (amp, A) Amount of substance- mole (mol) While not a base unit, the Liter (L) is commonly seen.

Commonly Used Prefixes Giga - G 1,000,000, Mega - M 1,000, Kilo - k 1, Deci -d Centi -c Milli -m Micro -m Nano -n

Deriving the Liter Liter is defined as the volume of 1 dm 3 A milliliter is the volume of 1 cm 3

Mass and Weight Mass is measure of resistance to change in motion, measured in grams. Weight is force of gravity. Sometimes used interchangeably, which while technically isn’t correct is usually fine since the problems are always done at earth’s gravity. Mass can’t change, weight can

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

Uncertainty Systematic error - Same direction of error each time Better precision implies better accuracy You can have precision without accuracy You can’t have accuracy without precision

Dimensional Analysis Using the units to solve problems Note: While some of the examples are using English units (ft, yd…) in this class you will only be responsible for converting from SI units to SI units unless the conversion factors are given.

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

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

Examples 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? Warp 1.71 = 5.00 times the speed of light speed of light = 3.00 x 10 8 m/s 1 knot = 2000 yd/h exactly

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

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 A measure of the average kinetic energy of the particles of a sample. While we might occasionally refer to °F, in this class we will be using °C and Kelvin Kelvin can easily be converted to °C by the following: K = °C Note that Kelvin doesn’t have a degree sign.

Density Ratio of mass to volume Density = mass / volume OR D = m / v Useful for identifying a compound Useful for predicting weight An intensive property - does not depend on what the material is. NOTE: This is one of the formulas that you will have to know – it won’t always be supplied on tests and quizzes.

Density Problem 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 A Liter drum weighs 35.0 kg. when empty. What will the total mass be when filled with ethanol ? Density of ethanol is g/cm 3