# Question #755d3

##### 1 Answer

Percent means "out of 100." So percent composition refers to how many parts (grams, litres, moles, etc.) there are in 100 parts (grams, litres, moles, etc.) of a substance.

Chemists use four types of percent composition.

**Percent by mass (m/m)**

Mass percent is the mass of a component divided by the total mass of the sample, multiplied by 100%.

**Percent mass by volume (m/v)**

Volume percent is the mass of a component divided by the volume of the sample, multiplied by 100%.

**Example**: What is the mass by volume percent of NaOH if you dissolve 5.00 g of NaOH in enough water to make 100 mL of solution?

**Percent by volume (v/v)**:

Volume percent is the volume of a component divided by the volume of the sample, multiplied by 100%

**Example**: What is the volume percent of ethanol in a 750 mL bottle of wine that contains 94 mL of ethanol?

Mole percent is the moles of a component divided by the total moles of the sample, multiplied by 100%

**Example**: A solution contains 1.00 mol of NaOH in 5.00 mol water. What is the mole percent of NaOH?

Total moles = 1.00 mol + 5.00 mol = 6.00 mol