If the quantity of metal in a metallic oxide is 60%, what is its equivalent weight?

Aug 13, 2017

$\text{12 g}$

Explanation:

The idea here is that you're looking for the mass of this unknown metal that can combine with $\text{8 g}$ of oxygen, which is what the equivalent mass of the metal tells you in this context.

To make the calculations easier, pick a $\text{100-g}$ sample of this metal oxide. According to its percent composition, this sample will contain

• 60%color(white)(.)"metal " stackrel(color(white)(color(blue)("100 g sample")aaa))(rarr) " 60 g metal"
• 40%color(white)(.)"oxygen " stackrel(color(white)(color(blue)("100 g sample")aaa))(rarr) " 40 g oxygen"

So, you know that $\text{60 g}$ of this unknown metal combine with $\text{40 g}$ of oxygen, which means that $\text{8 g}$ of oxygen will combine with

8 color(red)(cancel(color(black)("g oxygen"))) * "60 g metal"/(40color(red)(cancel(color(black)("g oxygen")))) = "12 g metal"

Therefore, you can say that the equivalent mass of the metal is equal to

$\textcolor{\mathrm{da} r k g r e e n}{\underline{\textcolor{b l a c k}{\text{equivalent mass of metal in 60% metal oxide = 12 g}}}}$