Question

3. A 0.500 g sample of nitrogen gas combines with 1.140 g of oxygen gas to form NO2. If the atomic mass of oxygen is 16.000, calculate the atomic mass of nitrogen from this data.

Answer 1

Answer;

= 18.24

Explanation;

The ratio of N and O in the formula NO2 IS 1:2

Mass of nitrogen gas is 0.500 g

Moles of nitrogen will be;

= 0.500/16 = 0.03125 moles

Therefore;

The moles of Oxygen from the ratio will be;

= 0.03125 × 2 = 0.0625 moles

But; 0.0625 moles is equal to 1.140 g of Oxygen

The atomic number (mass in 1 mole) will be;

= 1.140 /0.0625

= 18.24

Thus the atomic number of Oxygen from the data is 18.24

Answer 2

The balanced chemical equation for the given reaction is:

N₂ + 2O₂ → 2NO₂

According to the given balanced equation, 2 moles of O₂ combines with 1 mole of O₂

Given, Mass of O₂ = 1.140 g

Atomic mass of O = 16 amu

Molar mass of O₂ = 16 x 2 = 32 g/mol

Now to calculate the moles of N₂:

1.14 g of O₂ x (1 mole of O₂/ 32 g of O₂) x (1 mol of N₂/ 2 mol O₂) = 0.0178 mol of N₂

Molar mass = mass/ moles  

Given, Mass of N₂ = 0.500 g

Molar mass of N₂ = 0.500 g / 0.0178 mol = 28 g/mol

Atomic mass of N = 28/2 = 14 amu

Therefore, the atomic mass of N is 14 amu