Welcome to AP Chemistry

What is AP Chemistry? It is several things Equivalent of a 1st 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 www.scramlinged.com

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) 3200 2 significant figures 3200. 4 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.

Scientific Method Metric System Uncertainty 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. (a 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.

Law Observations Theory (Model) Hypothesis Modify Experiment Prediction Law Experiment

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 1,000,000,000 109 Mega - M 1,000,000 106 Kilo - k 1,000 103 Deci - d 0.1 10-1 Centi - c 0.01 10-2 Milli - m 0.001 10-3 Micro - m 0.000001 10-6 Nano - n 0.000000001 10-9

Deriving the Liter Liter is defined as the volume of 1 dm3 A milliliter is the volume of 1 cm3

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

Using the units to solve problems Dimensional Analysis Using the units to solve problems

Dimensional Analysis Use conversion factors to change the units 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 108 m/s 1 knot = 2000 yd/h exactly

Examples 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 = 3.888 g 1 oz. ap = ? oz. troy What is the mass of 1 scruple in grams?

Examples The speed of light is 3.00 x 108 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: °C + 273 = K 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 amount of material is.

Density Problem # 1 An empty container weighs 121.3 g. filled with Carbon Tetrachloride (density 1.53 g / ml ). The container weighs 283.2 g. What is the volume of the Carbon Tetrachloride ?

Density Problem # 1 answer An empty container weighs 121.3 g. filled with Carbon Tetrachloride (density 1.53 g / ml ). The container weighs 283.2 g. What is the volume of the Carbon Tetrachloride ? Step 1: List the given info Mass of Container = 121.3 grams Density of Carbon Tetrachloride = 1.53 g / mL Mass of both = 283.2 grams Volume of Carbon Tetrachloride = ? Step 2: Write down the formula Density = Mass/Volume (D = m/V)

Density Problem # 1 answer Step 3: Substitute 1.53 = mass / VOLUME We need the mass: 283.2 – 121.3 = 161.9 grams 1.53 = 161.9 / Volume Step 4: Solve Volume = 105.8 mL

Density Problem # 2 A 55.0 gallon drum (barrel) weighs 75.0 lbs when empty. What will the total mass be when filled with ethanol (in pounds) ? density of ethanol = 0.789 g / mL 1 gallon = 3.78 L 1 lb = 454 g

Density Problem # 2 answer For properties such as Density, it is quite common to use it as a way to get to another value. So in this problem, we are using more problem solving techniques, such as unit analysis.

Density Problem # 2 answer Step 1: Determine the volume of the drum in mL, which equals the volume of ethanol. 55 x 3.78 = 207.9 L  207,900 mL Step 2: Determine the mass of ethanol. .789 = mass / 207,900 mass = 164,033.1 g

Density Problem # 2 answer Step 3: Convert grams of ethanol to lbs. 164,033.1 / 454  361.31 lbs of ethanol Step 4: Add the mass of the ethanol to the mass of the drum 361.31 lbs + 75 lbs (drum) = 436.31 lbs NOTE: We will not be using lbs in class.

Classification of Matter There are three states of matter that we are primarily interested in: Solid Liquid Gas Solid: Definite Shape & Definite Volume Liquid: Indefinite Shape & Definite Volume Gas: Indefinite Shape & Indefinite Volume

Classification of Matter Lots of Vocabulary Words here Mixture: Composed of different parts that are making up one substance. Homogeneous – Equal composition throughout Heterogeneous – Varying composition A homogeneous mixture is called a solution.

Classification of Matter Pure Substance: Has a constant composition, such as water. All elements or compounds are Pure Substances.

Classification of Matter Physical v. Chemical Changes A physical change doesn’t change the composition of the actual chemical structure of the material. Examples of physical changes: Boiling water Cutting a piece of paper

Classification of Matter Physical v. Chemical Changes A Chemical change does change the composition of the actual chemical structure of the material. Exam ples of physical changes Burning a material Undergoing a chemical reaction (rxn).

Classification of Matter Separation Techniques Distillation: Using differences in Boiling Points to separate liquids. Saltwater is distilled to obtain fresh water Filtration: Using particle size to separate components Coffee filters work on this principle.

Classification of Matter Chromatography A separatory technique that uses different different solubilities of materials to separate a liquid or a gas from a solid. This is more often used for chemical analysis than for everyday use.

Classification of Matter Four words in Chemistry that are important to keep organized are: Atom, Molecule, Element, & Compound Element: A single type of material, that can’t be broken down. There are 92 naturally occuring elements and 118 overall. Examples: Lead, Oxygen, and Gold

Classification of Matter Compound: A substance that is created from a combination of elements. There are about 50 million compounds and the list is growing every day. Examples: Water, salt, and gasoline.

Classification of Matter Atom: An atom is the smallest bit of an element that still has the properties of that element. Molecule: A molecule is the smallest bit of a compound that still has the properties of that compound.