Question

given : molar mass of carbon is 12gmand oxygen is 16gm. Avagadro number N₀= 6.022 x 10²³ .

1. calculate the mass of 0.5 moles of CO₂ .
2. calculate the number of particles in 8gmof oxygen molecule .

Answer 1

1) Molar mass of CO₂ = 12 + 2$\times$16 = 44 g mol^-1
Number of moles (n) = 0.5 moles
n = $\frac{\text{Given mass}}{\text{Molar mass}}$

0.5 = $\frac{Givenmass}{44}$
Mass of 0.5 moles of CO₂ is 22 g.

2) Molar mass of oxygen molecule = 32 g mol^-1
32 g of oxygen molecule contains = 6.022$\times$10²³ particles
8 g of O₂ = $\frac{6.022\times {10}^{23}}{32}\times 8$ = 1.5 $\times$10²³ particles