How many molecules are in 10.8 grams of C12H22O11?

Question

How many molecules are in 10.8 grams of C12H22O11?

Answer 1

First you want to divide by the molar mass in order to find the number of moles that you have

Moles = Mass / Molar Mass = 10.8 g / 342.3 g/mol = 0.03155 mol

From there then I would multiply by Avogadro's number in order to find the number of molecules

0.03155 mol x 6.022 x 10^23 molecules/mole = 1.9 x 10^22 molecules

Answer 2

Overall conversions: sample in grams —> sample in moles —> sample in molecules

The molecular mass of C₁₂H₂₂O₁₁ is 342.34 grams/mol.

—> Found by adding the molecular masses of the constituent atoms within the molecule:

Carbon molecular mass = 12.01 g/mol, times 12 = 144.12 g/mol

Hydrogen molecular mass = 1.01 g/mol, times 22 = 22.22 g/mol —> SUM = 342.34 g/mol

Oxygen molecular mass = 16.00 g/mol, times 11 = 176.00 g/mol

If a sample contains 10.8 g of C₁₂H₂₂O_11, to find moles of the compound you divide by the molecular mass.

—> This is the same as multiplying by the reciprocal of the molecular mass:

10.8 g x (1 mol / 342.34 g) = 0.03 moles C₁₂H₂₂O₁₁

To covert from moles to molecules, use Avogadro’s number:

—> There are 6.02 x 10²³ molecules of C₁₂H₂₂O₁₁ per mol of C₁₂H₂₂O₁₁

Multiply moles by Avogadro’s number: 0.03 moles x (6.02 x 10²³ molecules / mol) = 1.81 x 10²² molecules C₁₂H₂₂O₁₁ in 10.8 g sample.

I hope this helps!