Question

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

Answer 1

`"12 g"`

Explanation:

The idea here is that you're looking for the mass of this unknown metal that can combine with `"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 `"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 `"60 g"` of this unknown metal combine with `"40 g"` of oxygen, which means that `"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

`color(darkgreen)(ul(color(black)("equivalent mass of metal in 60% metal oxide = 12 g")))`