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

1 Answer
Ernest Z.
Feb 7, 2018

a) #63.5/159.5 × 1000#

Explanation:

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

#A_text(r) = 63.5 color(white)(mll)32 color(white)(mm)16#
#color(blue)(color(white)(mmml)"Cu"color(white)(mm)"S"color(white)(mml)"O"_4)#
#M_text(r) = "63.5 + 32 + 4×16 = 159.5"#

The formula tells you that there are 63.5 units of copper in 159.5 units of #"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 #"CuSO"_4# you have

#"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.

Related questions
See all questions in Percent Composition
Impact of this question
3682 views around the world
You can reuse this answer
Creative Commons License