# 1 tonne of CuSO4 contains how many kg of copper? (Mr; Cu=63.5, S=32, O=16)

## Options a) 63.5/159.5 * 1000 b) 63.5/96 * 1000 c) 63.5/159.5 * 1 d) 63.5/159.5 * 1/1000

Feb 7, 2018

a) 63.5/159.5 × 1000

#### Explanation:

Let's look at the formula of copper(II) sulfate..

${A}_{\textrm{r}} = 63.5 \textcolor{w h i t e}{m l l} 32 \textcolor{w h i t e}{m m} 16$
$\textcolor{b l u e}{\textcolor{w h i t e}{m m m l} {\text{Cu"color(white)(mm)"S"color(white)(mml)"O}}_{4}}$
${M}_{\textrm{r}} = \text{63.5 + 32 + 4×16 = 159.5}$

The formula tells you that there are 63.5 units of copper in 159.5 units of ${\text{CuSO}}_{4}$

The units can be anything you want.

We usually use grams, but they could be micrograms, kilograms, tonnes, pounds, etc.

Thus, in 1 t of ${\text{CuSO}}_{4}$ you have

$\text{Mass of Cu" = 1000 color(red)(cancel(color(black)("kg CuSO"_4))) ×"63.5 kg Cu"/(159.5color(red)(cancel(color(black)("kg CuSO"_4)))) = "398 kg Cu}$

Thus the numbers in the calculation are 1000 ×63.5/159.5#.

This question is an excellent example of why you should always use units in your calculations.

If the units don't cancel correctly, you know you have done something wrong.