Question

The ionic compound, MClx (where M is a metal and Cl is chlorine) has a formula mass of 190 g/mol and a mass percent of chlorine of 74.8%. What is the atomic mass of the element

Answer 1

Answer:

$48.2\ \text{g/mol}$

Explanation:

Formula mass of compound = 190 g/mol

Molar mass of chlorine = 35.45 g/mol

$MCl_x$ means 1 mole of $M$ is present and $x$ moles of $Cl$ are present.

So,

$190=M+xCl\\\Rightarrow 190=M+x35.453$

Mass of percent of chlorine = 74.8%

$0.748=\dfrac{\text{Mass of }Cl}{190}\\\Rightarrow \text{Mass of }Cl=0.748\times 190\\\Rightarrow \text{Mass of }Cl=142.12\ \text{g}$

Now

$35.45x=142.12\\\Rightarrow x=\dfrac{142.12}{35.45}\\\Rightarrow x=4$

$190=M+4\times 35.45\\\Rightarrow M=190-4\times 35.45\\\Rightarrow M=48.2\ \text{g\mol}$

Atomic mass of the element M is $48.2\ \text{g/mol}$.