Question

What quantity of copper (II) oxide will 2.80 litres of hydrogen at N.T.P. ?

Answer 1

In these kinds of situations the first thing important is to write a balanced chemical equation. After that we will get the mole to mole ratio through the comparison which is $1:1$ in this case. After that we can find the amount of $CuO$ by using the unitary method.

Complete step by step answer:
Firstly we have to sort out
The balanced equation for the given problem will be:
$CuO + {H_2} \to Cu + {H_2}O$
Where both $CuO$ and ${H_2}$ both are $1mole$
Now,
We have to find the answer through step by step process:
Step 1: We have to find the weight of $1{\text{ }}mole$ $CuO$ :-
Atomic mass of $Cu$ = $63.5g$
Atomic mass of $O$ = $16g$
Therefore, for $1{\text{ }}mole$ $CuO$ the mass =
$= Cu + O \\\ = 63.5g + 16g \\\ = 79.5g \\\$
Step2: In this step we have to find the mole to mole relation for the reaction so that we can perform the calculations.
By the study of reaction we are certain that the mole to mole reaction ratio of ${H_2}$ to the $CuO$ is $1:1$
$22.4L$ of ${H_2}$ react with $CuO$ at N.T.P = $79.5g$
$2.8L$of ${H_2}$ react with $CuO$ at N.T.P = $\dfrac{{(79.5g)}}{{(22.4L)}} \times (2.8L) = 9.94g$
Therefore, the answer would be $9.94g$.

Note:
In this type of question (specially regarding copper) the chemical formula of the compound should be taken care of because of the multiple oxidation states that are shown by $Cu$ . Apart from that mole interconversion is an important step. It should be kept in mind that for ideal state $22.4L = 1mole$ .