Question

The amount of zinc required to produce \[224{\text{ }}mL\] of \[{H_2}\] at STP on treatment with dilute \[{H_2}S{O_4}\] will be:
A. \[65\,g\]
B. \[0.065\,g\]
C. \[0.65\,g\]
D. \[6.5\,g\]

Answer 1

Hint: Here, in this question, there is a reaction of zinc and sulphuric acid is given. It produces hydrogen gas. STP is a fundamental chemical principle. In the STP system, both pressure and temperature are in their normal states. In this system, the pressure and temperature are \[760\,torr\] and \[273\,K\] , respectively. To compute the volume of gas in STP, use the usual formula. In this standard formula, the pressure is recorded in torr and the temperature is measured in Kelvin.

Formula Used:
The number of moles can be calculated by the formula as follows:
\[No.\,of\,moles = \dfrac{{volume\,at\,STP\,(mL)}}{{22400}}\]
The number of moles can also be calculated by the formula as follows:
\[No.\,of\,moles = \dfrac{{mass}}{{molar\,mass}}\]

Complete Step by Step Solution:
The following is the chemical equation for the given reaction:
\[Zn + {H_2}S{O_4}\xrightarrow{{}}ZnS{O_4} + {H_2}\]

From the reaction stoichiometry, one mole of zinc reacts with one mole of sulphuric acid. It produces one mole of hydrogen and one mole of zinc sulphate.
1 mole zinc reacts to produce 1 mole hydrogen.
We know that the volume of gas at STP is \[22.4\,L\] or \[22400\,mL\].
So, we can say that,
\[{\text{volume of 1 mol hydrogen}} = 22400{\text{ }}mL\]

Now, the molar mass of zinc is \[65{\text{ }}g/mol\].
So, we can say that,
\[1{\text{ }}mol{\text{ }}Zn = 65\,g\]
Let us calculate the amount of zinc required for a given reaction as follows:
${\text{Amount of Zn}} = \dfrac{{65}}{{22400}} \times 224 \\$
$ \Rightarrow {\text{Amount of Zn}} = 0.65\,g \\ $

As a result, \[0.65\,g\] zinc is required to produce \[224{\text{ }}mL\] of \[{H_2}\] at STP on treatment with dilute \[{H_2}S{O_4}\].

Additional Information: Stoichiometry is based on the law of conservation of mass, which states that the entire mass of reactants is equivalent to the full mass of products, implying that relationships between product and reactant quantities are usually positive integer ratios. This demonstrates that if you know the number of individual goods, calculating the product amount is simple.

Note: Standard reference conditions are essential for expressions of fluid flow rate, liquid and gas quantities that are significantly reliant on temperature and pressure. STP is extensively used because it uses standard state conditions in calculations.