Question

Vehicle gasoline has many slightly different compositions depending on local laws. However, on average it has a density of 0.737 kg/L. This morning you pumped 7.2 gallons of gasoline in order to fill up your fuel tank. How much mass have you added to your car, in kilograms?
1 gal = 3.785 L

Use appropriate Sig Figs in answer!

Answer 1

Answer: 20.1 kg.

Explanation:

To calculate mass of a substance, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

We are given:

Density of gasoline = $0.737kg/L$

Volume of gasoline = $7.2gallons=7.2\times 3.785L=27.252L$     (Conversion factor: $1gal=3.785L$ )

Putting values in above equation, we get:

$0.737kg/L=\frac{\text{Mass of gasoline}}{27.252L}\\\\\text{Mass of gasoline}=20.084kg$

The rule apply for multiplication and division is :

The least precise number present after the decimal point determines the number of significant figures in the answer, thus the answer musty have three significant digits.

Hence, the mass added is 20.1 kg.