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.