# How do you convert 1.55 moles of water to grams?

Jun 14, 2016

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 (${H}_{2} O$) take the sum of the molar masses of $2$ hydrogen and $1$ oxygen atom:

• Hydrogen ($H$) = $1.008$ g/mol $\cdot 2 = 2.016$ g/mol
• Oxygen ($O$) = $15.999$ g/mol
• Molar mass of ${H}_{2} O$ = $2.016 + 15.999 = 18.015$ 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 $\cdot 1.55$ mol = $27.9$ gram