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1 Quiz 4 Answer Key (Chapter 7: Unit Conversions, Chapter 8: Density, Chapter 10: Percents) 1. 0.38% = __0.0038___ as a decimal 2. 0.0026 = __0.26%___ as a percent 3. 0.015% = ___0.015 ___ /100 4. The density of B-mercaptoethanol is 1.1 g/mL. If you need to add 0.18 g of this chemical to a solution, how much volume should you measure out? 1.1 g = 0.18 g X = (0.18 g)(1 mL) = 0.16 mL 1 mL X 1.1 g SOLVE PROBLEMS 5-6 USING THE PROPORTION METHOD Fill in the Blanks 1 week = 7 days 5. 12 weeks = ____84__ days = ____2016___ hours 1760 yds = 1 mi 6. 1 day = 24 hours 1 yd = 3 ft _0.0034___ mi = ____6____yds = 18 ft 1 ft = 12 in 2 SOLVE PROBLEM 7 USING THE UNIT CANCELLING METHOD Relationships 1 km = 1000 m = 103 m 1 cm = 10 mm 1 m = 1000 nm = 103 nm 1 m = 100 cm = 102 cm 1 mm = 1000 m = 103 m 2.5 cm = 1 in 7. 1.5 cm = __15_ mm = _1.5 X 104_m = 1.5 X 107__ nm 8. A recipe to make 1 liter of a laboratory solution is shown as follows: SOLUTION X COMPONENT GRAMS Mg acetate 1.00 Na azide 0.0001 Mg sulfate 0.456 Tris 15.00 mg for 200 mL 200 0.02 91.2 3000 How much of each component is required to prepare 200 mL of the same solution? Express the amounts of each component needed in mg.