In Class Activity Chem 107 Cypress College
Metric System Give the metric prefix that corresponds to each of the following: a. 1,000,000 b. 10 6 c. 10-3 d. 10-2 e. 10-9 f. 0.000001
Metric System The metric system or International System (SI) is a decimal system of units that uses factors of 10 to express larger or smaller numbers of these units.
Metric System
Scientific Notation For each of the following numbers, if the number is rewritten in standard scientific notation, will the exponent of the power of 10 be positive (+) or negative (-)? a. 1,942,200 c. 0.151 b. 15 d. 0.0000000721 Express each of the following numbers in standard scientific notation. a. 9,367,421 e. 6.24 x 10 2 b. 7241 f. 6319 x 10 2 c..0005519 g. 0.000000007215 d. 5.408 h. 0.0721
Scientific Notation Scientific notation is writing a number as the product of a number between 1 and 10 multiplied by 10 raised to some power. Used to express very large numbers or very small numbers as powers of 10. Expression using scientific notation: Exponent is equal to the number of places the decimal point is moved. Sign on exponent indicates the direction the decimal was moved Moved right negative exponent Moved left positive exponent
Scientific Notation Express each of the following as an ordinary decimal number. a. 4.83 x 10 2 g. 9.999 x 10 3 b. 7.221 x 10-4 h. 1.016 x 10-5 c. 6.1 x 10 0 i. 1.016 x 10 5 d. 9.11 x 10-8 j. 4.11 x 10-1 e. 4.221 x 10 6 k. 9.71 x 10 4 f. 1.001 x 10 1 l. 9.71 x 10-4
Uncertainty in Measurement
Significant Figure Significant Figures include both the certain part of the measurement as well as the estimate.
Significant Figure
Significant Figure
Significant Figure
Significant Figure Indicate the number of significant figures implied in each of the following statements: a. The population of the United States is 250 million. b.one hour is equivalent to 60 minutes. c. There are 5280 feet in 1 mile. d.jet airliners fly in at 500 mi/h. e. The Daytona 500 is a 500-mile race. Express each of the following numbers in standard scientific notation, rounding off each to three significant digits. a. 422.65 x 10-3 d. 22.9987 x 10-5 b. 71.246 x 10 5 e. 9.7222 x 10 5 c. 0.00044515 f. 0.0048545 x 10 5
Significant Figure Rules for Counting Significant Figures 1. All nonzero digits are significant 21.2 has 3 significant figures 2. An exact number has an infinite number of significant figures. Counted numbers: 35 pennies Defined numbers: 12 inches in one foot
Significant Figure Rules for Counting Significant Figures 3. A zero is significant when it is between nonzero digits (captive zero) 403 has 3 significant figures at the end of a number (trailing zero) that includes a decimal point 0.050 has 2 significant figures 22.0 has 3 significant figures 20. has 2 significant figures
Significant Figure Rules for Counting Significant Figures 4. A zero is not significant when it is before the first nonzero digits (leading zero) 0.0043 has 2 significant figures a trailing zero in a number without a decimal point 2400 has 2 significant figures 9010 has 3 significant figures
Significant Figure The result of the calculation cannot be more precise than the least precise measurement.
Significant Figure Evaluate each of the following and write the answer to the appropriate number of significant figures. a. 212.2 + 26.7 + 402.09 = b. 1.0028 + 0.221 + 0.10337 = c. 52.331 + 26.01 0.9981 = d. 2.01 x 102 + 3.014 x 103 = Without actually performing the calculations indicated, tell how many significant digits the answer to the calculation should be contain. a. (10.12 + 17.381 + 18.2) (1.41) = b. (0.500 x 44.02) (4.000 3.00) = c. (0.15 + 1.045) (0.280 0.05 ) =
Significant Figure in Calculation Calculations involving Addition and Subtraction The result has the same precision (same number of decimal places) as the least precise measurement (the number with the fewest decimal places). 1587 g - 120 g =? 120 g is the least precise measurement. The answer must be rounded to 1470 g. Key Idea: Match precision rather than significant figures!
Significant Figure in Calculation Calculations involving Multiplication or Division The result has as many significant figures as the measurement with the fewest significant figures 9.00 m 100 m = 900 m 2 (100 has only 1 significant figure) 9.00 m 100. m = 900. m 2 (both have 3 significant figures ) 9.0 m 100. m = 9.0 10 2 m 2 (9.0 has 2 significant figures ) Key Idea: Match significant figures!
Significant Figure
Dimensional Analysis: Unit Conversion
Dimensional Analysis: Unit Conversion
Temperature Conversion
Temperature Conversion
Temperature Conversion
Dimensional Analysis: Unit Conversion Density 1. What is the density of sulfuric acid if 60.0 ml of acid weighs 112.4 grams? 2. The density of oil is 0.879 g/ml. How many grams of oil are needed to fill a 25.00 ml graduated cylinder? 3. The density of mercury is 13.6 g/ml. How many milliliters of mercury are needed to give a mass of 0.250 lb.? 4. What is the density of a block of iron that measures 7.00 cm x 5.00 cm x 3.00 cm and weighs 750.0 g?
Dimensional Analysis: Unit Conversion Density 5. The density of gasoline is 0.850 g/ml. What is the mass of 400.0 ml of gasoline? 6. The density of aluminum is 2.70 g/cm3. A piece of aluminum foil that is 10.00 cm on each side has a mass of 440. mg. How thick is the piece of foil? 7. A graduated cylinder contains 7.00 ml of water. After adding 18.001 grams of sulfur the water level is at 15.90 ml. What is the density of sulfur? 8. Air weighs about 8.0 lb per 100. cubic feet. What is the density of air in (a) grams per cubic foot? (b) grams per liter?