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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.

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Presentation on theme: "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."— Presentation transcript:

1 Welcome to AP Chemistry

2 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 2 @ 7:45 l Hard work l Now lets work

3 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 arent

4 Which zeroes count? l In between other sig figs does l Before the first number doesnt l After the last number counts iff l it is after the decimal point l the decimal point is written in l 3200 2 sig figs l 3200. 4 sig figs

5 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.

6 More Preliminaries Scientific Method Metric System Uncertainty

7 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

8 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

9 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

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

11 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

12 Metric System l Base Units l Mass - kilogram (kg) l Length- meter (m) l Volume – cubic meter (m 3 ) l Time - second (s) l Temperature- Kelvin (K) l Electric current- ampere (amp, A) l Amount of substance- mole (mol)

13 Prefixes l giga- G 1,000,000,00010 9 l mega - M 1,000,00010 6 l kilo - k 1,00010 3 l deci-d0.1 10 -1 l centi-c0.01 10 -2 l milli-m0.001 10 -3 l micro-m0.000001 10 -6 l nano-n0.000000001 10 -9

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

15 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 cant change, weight can

16 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

17 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 cant have accuracy without precision

18 Dimensional Analysis Using the units to solve problems

19 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.

20 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?

21 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

22 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 = 3.888 g l 1 oz. ap = ? oz. troy l What is the mass of 1 scruple in grams? Examples

23 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?

24 Temperature and Density

25 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

26 0ºC 32ºF 0ºC = 32ºF

27 100ºC212ºF 100ºC = 212ºF 0ºC 32ºF 0ºC = 32ºF

28 100ºC212ºF 0ºC 32ºF 100ºC = 212ºF 0ºC = 32ºF 100ºC = 180ºF

29 100ºC212ºF 0ºC 32ºF 100ºC = 212ºF 0ºC = 32ºF 100ºC = 180ºF 1ºC = (180/100)ºF 1ºC = 9/5ºF

30 ºC ºF

31 ºC ºF (0,32)= (C 1,F 1 )

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

33 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

34 Density Problem l An empty container weighs 121.3 g. Filled with carbon tetrachloride (density 1.53 g/cm 3 ) the container weighs 283.2 g. What is the volume of the container?

35 Density Problem lAlA 55.0 gal drum weighs 75.0 lbs. when empty. What will the total mass be when filled with ethanol? density 0.789 g/cm 3 1 gal = 3.78 L 1 lb = 454 g


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