Question

Two minerals that contain $Cu$ are $CuFe{S_2}$ and $C{u_2}S$ . What mass of $C{u_2}S$ would contain the same mass of $Cu$ as is contained in $125{\text{ }}lb$ of $CuFe{S_2}$ ?

Answer 1

In order to answer this question, to calculate the mass of $C{u_2}S$ , first we will find the molecular mass of $CuFe{S_2}$ , that’s how we will get the amount of $Cu$ contained in $125{\text{ }}lb$ of $CuFe{S_2}$ . Now, we can find the mass of $Cu$ as it is contained in $125{\text{ }}lb$ of $CuFe{S_2}$ .

Complete answer:
Firstly, let us convert the weight into grams.
$\Rightarrow 125\,lb\,of\,CuFe{S_2} = 125 \times 453.59gm\,of\,CuFe{S_2} \\\ = 56,698.75gm\,of\,CuFe{S_2}$
Molecular mass of $CuFe{S_2}$ = $184gm$
$\Rightarrow 184g\,of\,CuFe{S_2}\,contain\,\,64gm\,of\,Cu \\\ \Rightarrow 56698.75g\,of\,CuFe{S_2}\,contain\, = \dfrac{{64}}{{184}} \times 56698.75g\,of\,Cu \\\ = 19721.304g\,of\,Cu$
According to the question;
$19721.304gm$ of $Cu$ will be contained in $C{u_2}S$
Molecular mass of $C{u_2}S = 160gm$
$\Rightarrow 160g\,of\,C{u_2}S$ contain $128gm$ of $Cu$
$\Rightarrow 1g\,of\,Cu$ will be contained in $\dfrac{{168}}{{128}}g\,of\,C{u_2}S$
$\Rightarrow 19721.304g\,of\,Cu$ will be contained in $\dfrac{{160}}{{128}} \times 19721.304g$ of $C{u_2}S$
$= \dfrac{{160}}{{128}} \times \dfrac{{19721.304}}{{453.59}}lb\,of\,C{u_2}S$
$= 54.37lb\,of\,C{u_2}S$ will contain the same mass of $Cu$ as contained in $125lb\,of\,CuFe{S_2}$ .

Note:
There are various methods used to extract copper from its ores depending on the nature of the ore. Sulfide ores such as chalcopyrite are converted to copper by a different method from silicate, carbonate or sulfate ores. Chalcopyrite, also known as copper pyrites and similar sulfide ores are the commonest ores of copper.