CHEM 121: Introduction to Chemistry
Setting up Conversion Problems
1) Find an equality expressing the same quantity in two different units—the unit
matching your measurement and the desired unit, or 1 step closer to.
Every equality (x = y) generates two conversion factors (x/y = 1; y/x = 1).
2) Multiply your measurement by the conversion factor which cancels the original unit.
Repeat until your measurement is expressed in the desired units.
Does your answer make sense? Check significant figures!
Example: A book masses 0.550 lb. What is this mass in grams? 1 kg = 2.205 lb.
Answer: The second equality needed is 1000 g = 1 kg.
0.550 lb x (1 kg/2.205 lb) x (1000 g/1 kg) = 249 g
CHEM 121: Introduction to Chemistry
Extra conversion problems
1 in = 2.54 cm
1 cm3 = 1 mL
1 kg = 2.205 lb
1 m = 3.28 ft
Convert each of the following as indicated:
a)
b)
c)
d)
e)
f)
g)
h)
0.063 m to cm
0.063 m to in
5802 g to kg
5802 g to lb
0.0071 mL to cL
2.1 x 105 µm to cm
2610 ft2 to m2
0.0000068 m3 to ml
What is the density of a 7.68 g plastic cube measuring 2.2 cm on each side? Will this
cube float or sink if placed in a glass of water?
What is the mass of a ceramic vase that displaces 48 ml of water when immersed in a
water bath? The density of the ceramic is 4.71 g/cm3.
The recommended dosage of a specific antibiotic is 15 g per kg body weight. It is
available as a solution containing 0.10 mg per 1.0 ml. How much of this solution should
be given to a 150. lb person?