advertisement

Practice Problems Chang, Chapter 1 Chemistry: The Study of Change 1.7 Measurement • A piece of platinum metal with a density of 21.5 g/cm3 has a volume of 4.49 cm3. What is its mass? Answer: 96.5 g 1 1.7 Measurement • The density of sulfuric acid in a certain car battery is 1.41 g/ml. Calculate the mass of 242 mL of the liquid. Answer: 341 g 2 6.4 Enthalpy of Chemical Reactions • Convert: a) 327.5°C (the melting point of lead) to degrees Fahrenheit; b) 172.9°F (the boiling point of ethanol) to degrees Celsius; c) 77 K, the boiling point of liquid nitrogen, to degrees Celsius. Answers: a) 621.5°F b) 78.3°C c) -196°C 3 1.8 Handling Numbers • Determine the number of significant figures in each of the following measurements a) b) c) d) e) 24 mL 3001 g 0.0320 m3 6.4 x 104 molecules 560 kg Answer: a) 2 b) 4 c) 3 d) 2 e) 2 4 1.8 Handling Numbers • Carry out the following arithmetic operations & round off the answers to the appropriate number of significant figures: a) b) c) d) e) 26.5862 L + 0.17 L 9.1 g – 4.682 g 7.1 x 104 dm x 2.2654 x 102 dm 6.54 g ÷ 86.5542 mL (7.55 x 104 m) – ( 8.62 x 103 m) Answers: a) 26.76 L b) 4.4 g c) 1.6 x 107 dm2 d) 0.0756 g/mL e) 6.69 x 104 m 5 1.9 Dimensional Analysis in Solving Problems • A roll of aluminum foil has a mass of 1.07 kg. What is its mass in pounds? Answer: 2.36 lb. 6 1.9 Dimensional Analysis in Solving Problems • The volume of a room is 1.08 x 108 dm3. What is the volume in m3? Answer:1.08 x 105 m3 7 1.9 Dimensional Analysis in Solving Problems • The density of the lightest metal, lithium (Li), is 5.34 x 102 kg/m3. Convert the density to g/cm3. Answer: 0.534 g/cm³ 8