How do you calculate the number of moles from mass?

To determine the number of moles from a given mass, the correct formula to use is based on the relationship defined in the concept of molarity, which connects mass, molar mass, and number of moles.

The formula states that moles are equal to the mass divided by the molar mass. Here’s the reasoning behind it:

1. Mass is measured in grams, and it represents the amount of substance you have.
2. Molar mass is defined as the mass of one mole of a substance, expressed in grams per mole (g/mol). It serves as a conversion factor between the mass of the substance and the number of moles.
3. By dividing the mass (in grams) by the molar mass (in grams/mole), you accurately convert the measurement of mass into the measurement of the amount of substance in moles.

This reflects the basic unit conversion principle where you are converting from one unit (grams) to another (moles) using a specific factor (molar mass). Therefore, using this formula allows you to quantify how many moles are present in your sample based on the mass you have measured.