3.1.2.2 The mole + Avogadro constant

How many protons are there in 6.0 g of nitrogen gas?

Avogadro constant, L = 6.022 × 10²³ mol^–1

• 1.3 × 10²³

• 9.0 × 10²³

• 1.8 × 10²⁴

• 3.6 × 10²⁴

A solution of volume 500 cm³ contains 150 g of ammonia.

What is the concentration, in mol dm^–3, of ammonia in this solution?

• 0.51

• 8.82

• 16.7

• 17.6

A gas cylinder contains 5.0 kg of propane.

How many propane molecules are in the cylinder?

The Avogadro constant, L = 6.022 × 10²³ mol^–1

• 6.8 × 10²²

• 7.2 × 10²²

• 6.8 × 10²⁵

• 7.2 × 10²⁵

Which sample of liquid has the greatest volume?

• 500 mg of pentane (density = 0.63 g cm^–3)

• 650 mg of propan-1-ol (density = 0.80 g cm^–3)

• 1.20 g of dichloromethane (density = 1.33 g cm^–3)

• 1.30 g of trichloromethane (density = 1.48 g cm^–3)

Which of these contains the greatest number of atoms?

• 127 mg of iodine

• 1.54 × 10⁻⁴ kg of phosphorus

• 81.0 mg of carbon dioxide

• 1.70 × 10⁻⁴ kg of ammonia

Which sample contains the most molecules?

The Avogadro constant, L = 6.022 x 10²³ mol⁻¹

• 2.10 × 10²² molecules of methane, CH₄

• 1.00 g of oxygen, O₂

• 65.0 mg of hydrogen, H₂

• 0.0300 mol of ethane, C₂H₆

Analysis of a sample of a chemical with formula C₂₂H₃₀N₆O₄S, showed that it contained 0.0195 mol of carbon.

What mass of nitrogen was present in the sample?

• 0.041 g

• 0.057 g

• 0.074 g

• 0.420 g

A solution of lead(ll) chloride (Mr = 278.2) contains 1.08 g of PbCl2 in 100 cm3 of solution. In this solution, the lead(ll) chloride is fully dissociated into ions.

What is the concentration of chloride ions in this solution?

• 3.88 × 10⁻³ mol dm⁻³

• 7.76 × 10⁻³ mol dm⁻³

• 3.88 × 10⁻² mol dm⁻³

• 7.76 × 10−2 mol dm−3

What is the number of atoms in 0.0100 mol of NH3?

(The Avogadro constant L = 6.022 × 1023 mol−1)

• 6.02 × 10²⁵

• 1.20 × 10²³

• 1.81 × 10²²

• 2.41 × 10²²

Which of the following contains the most chloride ions?

• 15 cm³ of 3.40 × 10⁻² mol dm⁻³ aluminium chloride solution

• 30 cm³ of 5.50 × 10⁻² mol dm⁻³ calcium chloride solution

• 40 cm³ of 2.30 × 10⁻² mol dm⁻³ hydrochloric acid

• 45 cm³ of 2.20 × 10⁻² mol dm⁻³ sodium chloride solution