Question

24.5 g KCIO, is heated to give o, which is allowed
to react completely with H, obtained from Zn and
H.SO, reaction. The weight of Zn required for the
purpose would be (Zn = 65)
(1) 39 g
(2) 789
(3) 24.5 g
(4) 19.5 g
​

Answer 1

Answer: 39 gm

Explanation:

2KClO3= 2KCl +3O2

Answer 2

Answer: The correct answer is Option 4.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$      .....(1)

For potassium chlorate:

Given mass of potassium chlorate = 24.5 g

Molar mass of potassium chlorate = 122.55 g/mol

Putting values in equation 1, we get:

$\text{Moles of potassium chlorate}=\frac{24.5g}{122.55g/mol}=0.199mol$

The chemical equations for the decomposition of potassium chlorate follows:

$2KClO_3\rightarrow 2KCl+3O_2$

By Stoichiometry of the reaction:

2 moles of potassium chlorate produces 3 moles of oxygen

So, 0.199 moles of potassium chlorate will produce = $\frac{3}{2}\times 0.199=0.298mol$ of oxygen

The chemical equation for the reaction of hydrogen and oxygen follows:

$2H_2+O_2\rightarrow 2H_2O$

By Stoichiometry of the reaction:

1 mole of oxygen reacts with 2 moles of hydrogen

So, 0.298 moles of oxygen will react with = $\frac{2}{1}\times 0.298=0.298mol$ of hydrogen

The chemical equation for the reaction of zinc and sulfuric acid follows:

$Zn+H_2SO_4\rightarrow ZnSO_4+H_2$

By Stoichiometry of the reaction:

1 mole of hydrogen are produced by 1 mole of zinc.

So, 0.298 moles of hydrogen are produced by = $\frac{1}{1}\times 0.298=0.298mol$ of zinc.

Now, calculating the mass of zinc by using equation 1, we get:

Molar mass of zinc = 65.38 g/mol

Moles of zinc = 0.298 moles

Putting values in equation 1, we get:

$0.298mol=\frac{\text{Mass of zinc}}{65.38g/mol}\\\\\text{Mass of zinc}=(0.298mol\times 65.38g/mol)=19.5g$

Hence, the correct answer is Option 4.