My question is about chemistry , it says calculate the number of atoms of Cl in 0.0425h of C2H4Cl2

Question

Can you Solve it step by step please ? I have a question about a step ,I want to get the number of moles of Cl , so I need to divide it’s mass(g) by its molar or molecular mass ,

will the molar mass be just 35.5 g/mol because it’s Cl

or will it be 71 g/mol because it Cl2.

I appreciate your help .

Answer 1

Well, it would be 35.5 for each Cl and there are 2 of them in the formula. But what you want is not the molar mass or atomic mass of Cl, but the molar mass of C2H4Cl2, which is ~99 g/mol. Then your calculations would be...

0.0435 g x 1 mole / 99 g = 0.000439 moles C₂H₄Cl₂ = 4.39x10^-4 moles

4.39x10^-4 moles C₂H₄Cl₂ x 6.02x10²³ molecules / mole x 2 Cl atoms/molecule = 5.29x10²⁰ atoms of Cl