Question

How do you convert 1.55 moles of water to grams?

Answer 1

By using the molar mass of water.

Explanation:

To get from moles to grams you need to use the molar mass which is the weight in grams of one mole (g/mol).

Each element has its own specific molar mass. For water (`H_2O`) take the sum of the molar masses of `2` hydrogen and `1` oxygen atom:

• Hydrogen (`H`) = `1.008` g/mol `* 2 = 2.016` g/mol
• Oxygen (`O`) = `15.999` g/mol
• Molar mass of `H_2O` = `2.016 + 15.999 = 18.015` g/mol

This means that `1` mole of water weighs `18.015` gram.
But you have `1.55` moles of water, so you multiply:

• `18.015` g/mol `* 1.55` mol = `27.9` gram