Question

18 carat gold contains 18 parts of gold and 6 parts of copper by mass calculate the concentration of gold and copper in 18 carat gold in% (m/m)

Answer 1

Given :

Parts of gold by mass in 18 carat gold = 18

Parts of copper by mass in 18 carat gold = 6

To Find :

Conc of gold and copper in 18  carat gold in % (m/m) = ?

Solution :

Let mass of gold  be $m_1$ .

And mass of copper be $m_2$ .

So, as per the question :

$\frac{m_1}{m_2} = \frac{18}{6} = \frac{3}{1}$

Now let $m_1$ = 3k  and $m_2$ = k

So, conc of gold =  $\frac{m_1}{m_1 + m_2}\times 100$

                           =$\frac{3k}{3k + k}\times 100 =\frac{3k}{4k} \times 100$

                           = 75 %

And conc of gold = $\frac{m_2}{m_1 + m_2}\times 100$

                             = $\frac{k}{3k + k } \times 100 =\frac{k}{4k} \times 100$

                             = 25 %

So, mass by mass % of gold and copper in 18 carat gold is 75 % and 25 % respectively .

Answer 2

Hope it will help you.

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