WAEC Chemistry 2024 Paper

Given:

m = 22g

M.V = 22.4dm$^3$

V = ?

First, calculate the number of moles n, by dividing mass of CO$_2$ by the molar mass of CO$_2$, since n = $\frac{\text{mass}}{\text{Molar mass}}$

Molar mass of CO$_2$ = 12 + (2 x 16) = 44g/mol

So, n = $\frac{\text{mass}}{\text{Molar mass}}$

n = $\frac{22}{44}$ = 0.5 mole

Also recall that number of moles of gases, n = $\frac{\text{Volume}}{\text{Molar Volume}}$

n = $\frac{V}{M.V}$

0.5 = $\frac{V}{22.4}$

V = 0.5 X 22.4

V = 11.2 dm$^3$

Alternatively,

Given the mass of CO$_2$ = 22g

Molar mass of CO$_2$ = 12 + (16X2) = 44g

number of moles, n = $\frac{m}{M}$ = $\frac{22}{44}$ = 0.5 mole.

If 1 mole of CO$_2$ = 22.4dm$^3$

0.5 mole of CO$_2$ = X dm$^3$

X = 0.5 x 22.4 = 11.2 dm$^3$