Chemistry Notes:Dimensional Analysis

In Chemistry and every-day life you will often need to express a measurement using a different unit than the one that was initially used.

Dimensional analysis is a way to analyze and solve problems by using the units, or dimensions, of the measurements.

Dimensional Analysis

To convert units, conversion factors are used. Conversion factors are equalities arranged as a ratio with different units.

For every equality, you can write two conversion factors. Ex. 1 dollar = 4 quarters

Correctly setting up dimensional analysis problems is essential to

being able to solve them.Steps of Dimensional Analysis

Identify the conversion factors you can use

Set up the conversion factors so that the units you do not want to have in your answer will cancel.

Multiply by the correct conversion factor (multiply the top, divide by the bottom)

1. How many feet are in 506 inches?

2. How many seconds are in 5.7 hours?

3. How many kilograms are in 78 ounces? (1 kilogram = 2.20 lbs, 16 ounces = 1 lb)

4. How many days are in 35,000 seconds?

5. How many inches are in 54 miles?

6. How many atoms of carbon are in 10.5 grams of carbon?

Hint: 1 mole of carbon = 12.0 g carbon 1 mole of carbon = 6.02x1023 atoms