Convert Mass or Grams to Moles

What Will Be Given: Grams of an Element or Compound

What To Calculate: Moles

Explanation:

Many chemical calculations require the number of moles of the element or compound. The common way to find the moles is to convert the given mass in grams to moles.

[lyte id=”CMnkSb2YsXI” \]

Steps to convert Grams to Moles

Determine the molecular formula of the molecule.
Find the atomic mass of each element in the molecule.
Find molecular mass by Multiply each element’s atomic mass by the number of atoms of that element in the molecule.
Divide the number of grams of the compound by the molecular mass to get the number of moles of the compound. Number of Moles = Mass of Compound / Molecular Mass of the compound

Tips and Tricks

In your problem, when you are given a value in moles, you can convert it to grams by multiplying the number of moles by molecular mass of the compound or element. Refer Example-2.

Grams of Element = (Molecular mass of Compound) x (moles)

Example -1 : Grams to Moles

Determine the number of moles of CO₂ in 480 grams of CO₂.

Solution:
Atomic mass of C = 12Atomic mass of O = 16Molecular mass of CO₂=12 x 1 + 2 x 16 = 44One mole of CO₂ weighs 44 gramsX moles of CO₂ weighs 480 grams

X moles CO₂ = 480 g x 1 mol/44 g = 10.9 moles

There are 10.9 moles CO₂ in 480 grams of CO₂

Example-2 : Moles to Grams

Determine the mass in grams of 3.60 mol of H2SO4.

Solution

Atomic mass of Hydrogen = 1

Atomic Mass of Sulfur = 32

Atomic Mass of Oxygen = 16

Molecular Mass of H2SO4 = 2 x 1 + 1 x 32 + 4 x 16= 98

One Mole of H2SO4 weights 98 grams

3.60 moles of H2SO4 weighs X grams

X grams = 3.6 x 98 = 352.8

3.60 moles of H2SO4 weighs 353 grams