2 MeasurementMeasurement: A quantity that has a number and a unit. Like 52 meters.
3 Scientific NotationWriting long numbers as smaller ones to a power of ten.1,400, = x = E6= x 10 — = 5.6E-415,093,000 = x = E7----- Meeting Notes (9/4/14 11:04) -----Rules - decimal after first number
4 Accuracy vs. Precision*Accuracy: How close a measurement comes to the correct value.*Precision: How close a series of measurements are to one another.
5 Determining Error of a measurement Error = Experimental Value - Accepted ValueCan be positive or negativePercent Error = error / accepted value * 100%orAlways positiveExample, you measured 99 cm, but it is 100 cm.----- Meeting Notes (9/4/14 11:04) -----define experimental and accepted.
6 Significant Figures: The digits in a measurement that are known plus one that is not known. Filled 43.1 mL
7 Rules for Sig Figs Non-Zero Numbers are always significant Ex) .236 m has 3 sig figs.Zeros between non-zero numbers are significant.Ex) 7003 m and m each have 4 sig figs.Leftmost zeros are not significantEx) m, 0.42 m, and .073 m each have 2 sig figs.Rightmost zeros are significant if they come before or after a period.Ex) m, m, and m each have 4 sig figs.
8 Rules for Sig FigsRightmost zeros with no decimal points are no significant.Ex) 300 m has 1 sig fig.Exactly defined quantities have an unlimited number of sig figs.Seen most when converting between measurements.60 min = 1 hour, cm = 1 m each have an unlimited number of sig figs.
9 Is a Zero a Significant Number or Not? 504 L.06 mL50.0 m7,000 km
10 Sig Figs in Calculations: Calculations cannot be more precise than the least precise measurement.Addition or subtraction - Round the final answer to the same number of decimal places as the measurement with the least number of decimal places.the last “shared column”.13.4 m m = 18.7 m
11 Sig Figs in Calculations: Multiplication or Division - The final answer should have the same number of sig figs as the measurement that has the least number of sig figs.m x 8.4 m = 21 m
12 In this class, delay rounding until the very end. (3.449L L) * 8.779L / 5.2L = 17L
13 International System of Units How much of something you have is given by Units. Like centimeters, kilometers, etc.SI is the standard measurement system for science.
14 * The five SI units used most by chemists are: Distance = meter (m)Mass = kilogram (kg)Temperature = kelvin (K)Time = second (s)Volume = liter (L)Amount = mole (mol).
15 Prefixes can be used in front of units for powers of 10.
16 Mass = how much “stuff” is in something Mass = how much “stuff” is in something. How much matter is in something.Weight = the pull on something by gravity.If I go to the moon, which changes and which stays constant?-Weight changes, mass stays the same.
17 Temperature:Celsius and Kelvin are units of temperature that are the same, just shifted.K = C + 273Water freezes at 0 C and at 273 K.Absolute Zero = 0 K; a K value will never be negative.
18 *Energy * Energy - The ability to do work or produce heat. Joule (J) is the SI unit of energy.Calorie (cal) is another unit of energy.1 J = .239 cal
19 ConversionsConvert 7 mm to m. Convert 12.4 Mm to cm.
20 Convert 7 km/ms to m/sAn experiment asks students to measure 1.50 g of Cu wire. All we have is a 40.0 g spool of Cu. How many students can do the experiment?
21 *Density *Density = mass / volume What is the density of 2 g of salt in a volume of 4 L?What is the density in g/L of 5 kg of salt in a volume of 6 mL?
22 If silver has a density of 10 If silver has a density of 10.5 g/L, what is the volume of a silver coin that has a mass of 14 g?
23 Density decreases as temperature increases. D=m/vAs T increases, V increases.Therefore, density decreases.
25 1. How many sig figs in: * E32. Perform these calculations and come up with answers that have the correct number of sig figs: E3 / E3 * 33. Convert 3.4 ng into kg.4. Convert 7E3 cm into Mm.5. What is the mass if a substance with a density of g/L has a volume of 3 L?
26 6. How many sig figs in:7. Convert 3 kg into g Convert 34 cm into m Convert 4 m into cm.8. You have a 4 kg box. You measure it to be 5.8 kg. What is the error? The % error?9. What is the difference between mass and weight? Accuracy and precision?
27 11. Put 5,009,000,000 into Scientific Notation 13. Put 8.7 * 10-4 into a regular number.
28 14. Which is the largest amount? A. 2*102 g B. 30 kg C. 45 mg D g15. Convert 40 Kelvin into Celsius16. Convert 99 Celsius into Kelvin.