Honors Chemistry
Dimensional Analysis (Factor – label method)
Name__________________
Remember, King Henry died unexpectedly drinking chocolate milk? Another method of going from one metric unit to
another involves multiplying by a conversion factor. A conversion factor is a fraction that is made up of a numerator and
denominator that have different numerical values and units but are equivalent. Conversions factors may be thought of as
“definitions”… not something that is measured by us in the lab, thus they do not limit sig figs. (In other words, ignore them
when determining sig figs. )
For example, 60 seconds = 1 min. Therefore, the conversions factors are: 60 sec/1 min or 1 min/60 sec.
Ex. How many milligrams are in 20 kilograms? Solve with dimensional analysis .
Conversion factors: 1000mg = 1 g and 1000g = 1 kg
1.
2.
3.
4.
Start with the original number and unit
Multiply by a conversion factor being sure that the unit to be discarded is on the bottom and the desired unit is on
the top.
Cancel the units
Perform numerical calculations
20 kg x 1000 g x 1000 mg = 2 x 107 mg
1 kg
1g
The following metric conversion factors need to be memorized:
1 kilometer (km) = 1000 meters (m)
1 liter (L) = 1000 mL
100 cenimeters (cm) – 1 m
1 kg = 1000 g
1 cm = 10 milimeters (mm)
1000 miligrams (mg) = 1 gram (g)
1 ml = 1 cm3= approximately 20 drops
We will not use the English system or English to metric conversions in chemistry, but here are some common conversion
factors:
Solve the following with dimensional analysis. Show all of your work. Be sure to cancel out the units.
Report correct Sig. figs.
1. 50.0 mL = ________ L
2. 25 g =___________ kg
Honors Chemistry
3. 400.0 mg = ________ kg
4. 20.2 cm = _________ mm
5. 350.0 sec = ________ hr
6. 2.1 years = __________ sec
7. 15.2 m =____________ mm
8. 0.75 L = ___________ mL
9. 6.4 kg =____________ g
10. 720.0 m = __________ km
11. 0.35 km = ___________m
12. 2.3 L = ______________mL
13. 4.5 yrds = ____________ in
14. 50.0 mm = _____________km
15. 15.0 mg = _____________ g
16. 15.0 kg = ______________g