Question

A grey coloured metal ‗Z‘ (Atomic weight=65) is used in making dry cell. It reacts with dil.

HCl to liberate a gas. What is the gas evolved? Calculate the minimum amount of ‗Z‘

required to produce 100 l 0f gas?

Answer 1

The grey coloured metal with atomic weight 65 u is zinc.

Zinc reacts with dilute HCl acid to liberate hydrogen gas.

Answer 2

Answer:

The metal is Zinc. It liberates hydrogen gas on reaction with HCl. The reaction is as follows:

Zn+ 2HCl → ZnCl2 + H2

So, the evolved gas is hydrogen.

From the reaction,

1 mole Zn will produce 1 mole Hydrogen

required hydrogen = 100 liters.

22.4 liter of hydrogen = 1 mole

1 liter of hydrogen = 122.4=10224 mole

100 liter of hydrogen = 10224×100=4.46 mole

So, 4.46 moles of hydrogen is being evolved. This will require 4.46 mole of Zn to react.

Amount of Zn in gram = atomic weight * no of mole = 65 * 4.46 = 289.9 g