Unit Conversions

Upon studying this section, you should be familiar with the following:

How to convert the units for a specific quantity.

Explanation:

Here, I am talking about converting units for a specific quantity. For example, converting a volume from m³ to L, or converting mass from kg to lb-m (pound-mass). This is done by multiplying the quantity you want to change by conversion factors, so that the units cancel giving the desired units.

Now, to illustrate how to perform a unit conversion, let's work out the following problem.

Knowing that 2000 lb = 1 ton, and 1 kilogram = 2.205 lb., determine the mass of a 3 ton garbage truck in kilograms?

We want to start with the 3 tons on the left hand side, and write the unit conversions as fractions so that the units cancel.

Example 2.a.1:

A 5 gallon bucket of tar weighs 30 lb. (pound-mass). What is the mass of the bucket in SI units (kg)?

Example 2.a.2:

For the same bucket as above, what is the volume in SI units (m³)

Example 2.a.3:

An 8 oz. cup of water is filled to the brim. How many liters is this?

Example 2.a.4:

Solve 2.a.3 again, but this time determine how many grams of water are in the cup. Remember that the density of water is 1 g/mL.

Example 2.a.5:

Find the number of gram-moles in the 8 oz. cup of water.

Example 2.a.6:

Find the number of pound-moles in the 8 oz. cup of water.