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

Hint: 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.