Question

Find out how many kilograms of copper does $1\;tonne$of $CuSO4$contain? (Given that: $Cu = 63.5,\;S = 32,\;O = 16$)
i) $398.12\;kg$of $Cu$
ii) $661.45\;kg$ of $Cu$
iii) $0.398\;kg$ of $Cu$
iv) $0.000398\;kg$ of $Cu$

Answer 1

Hint: We must note down the formula of copper sulphate, as it is the crucial step to find out the number of kilograms of copper in a tonne of copper sulphate. Try to find out how many units of copper are there in the total units of copper sulphate. Write down the atomic weights and understand the basic information like$1\;tonne$ is equivalent to $1000\;kg$.

Complete step by step answer:
Before trying to find the final answer let us write down the given data:
Atomic weights of each of the constituent elements of copper sulphate is given as $Cu = 63.5,\;S = 32,\;O = 16$
We know the molecular formula of copper sulphate is: $CuSO4$
Consider the molecular weight in units:
$
  Mr = 1 \times Cu + 1 \times S + 4 \times O \\
  Mr = 1 \times 63.5u + 1 \times 32u + 4 \times 16u \\
  Mr = 63.5u + 32u + 64u \\
  Mr = 159.5\;units \\
 $
From the previous calculation we can say that in a total of $159.5$ units of copper sulphate, there is $63.5$units of copper present. We can replace the ‘units’ with any common unit like grams, micrograms, tonnes or kilograms.
We said that $1$ tonne is equivalent to $1000$kilograms
$ \Rightarrow 1\;tonne\;CuSO_4 = 1000kg\;CuSO_4$
If we said that there is $63.5$kg of copper in $159.5$kg of copper sulphate, then we can also write that in $1000kg$ of copper sulphate there will be:
In $1000$kg of copper sulphate;
$
  Cu\;mass\; = \;1000kg.CuSO_4\; \times \;\dfrac{{63.5kg.Cu}}{{159.5kg.CuSO_4}} \\
 = \;398\;kg.Cu \\
 $

So the correct option for this question is option: i) $398.12\;kg$ of $Cu$, is there in $1$ tonne of copper sulphate.

Note: Copper sulphate is known to be a compound that has a crystalline blue color but copper sulphate written on its own as $CuSO4$ is not blue in color. The blue color comes into copper sulphate by the water molecules then it is known as a pentahydrate. The molecular form of the blue colored copper sulphate is $CuSO_4.5H_2O$. The anhydrous copper sulphate is light grey in color and it takes a powdered form.