Question

A sample of impure cuprite Cu2O2 , contains 66.6% copper. what is the percentage of pure Cu2O in the sample
(a) 75%
(b) 25%
(c) 60%
(d) 80%​

Answer 1

$\huge {\orange {\bf {\underline {\underline {ÀnSwer}}}:-}}$

A sample of impure cuprite $\sf Cu_2 O_2$, contains 66.6% copper. what is the percentage of pure$\sf Cu_2 O$ in the sample

☑ (a) 75 %

(b) 25%

(c) 60%

(d) 80%

Option (a) 75% is right

━━━━━━━━━━━━━━━

Explaination :-

100g of sample contains 66.66g of Cu

No. of moles = $\sf \dfrac{66.6}{63.6}$= 1.05moles .

1 mole of oxygen per 2 moles of Cu.

Moles of oxygen = $\sf \dfrac{1.05}{2}$= 0.53moles.

Weight of oxygen = 0.53 × 16g/mole = 8.42g.

Weight of $\sf Cu_2 O$ = 66.66 + 8.42 = 75.02g.

Percentage of $\sf Cu_2 O$= $\sf \dfrac{75.02}{100}$× 100 = 75 %

hence, Option (a) 75% is correct.

Answer 2

Answer:

Number of moles of Cu in 66.6g= 63.5/66.6g

=1.05 moles

We have 1 mole of oxygen per 2 mole of Cu

So, moles of oxygen is 0.525.

Weight of oxygen present= 0.525mol×16g/mol=8.4g

So, we have (66.6+8.4)g=75g

Our sample is 75% pure Cu2O.