IGCSE Stoichiometry

Magnesium nitride is formed when magnesium burns in air. Magnesium nitride is an ionic

compound.

What is the formula of magnesium nitride?

• MgN2

• Mg2N2

• Mg2N3

• Mg3N2

Which quantities of chemicals will react exactly with no reactants left over?

• 12 g of carbon and 12 g of oxygen

• 12 g of carbon and 48 g of oxygen

• 12 g of magnesium and 16 g of oxygen

• 24 g of magnesium and 16 g of oxygen

The gas hydrazine has the molecular formula N2H4.

Hydrazine burns in air to form nitrogen gas and steam.

N2H4(g) + O2(g) → N2(g) + 2H2O(g)

Which statements are correct?

1 1 mole of hydrazine gives 72dm3

of gaseous products when it reacts with oxygen at

room temperature and pressure.

2 The empirical formula of hydrazine is NH2.

3 The total number of atoms in 1 mole of hydrazine is 6 × the Avogadro constant.

4 The volume of 1 mole of hydrazine at room temperature and pressure is 6 × 24 dm3

• .1, 2 and 3

• 1 and 2 only

• 2, 3 and 4

• 3 and 4 only

What is the definition of relative atomic mass, Ar?

• A

• B

• C

• D

The concentration of a hydrochloric acid solution is 0.5 mol / dm3

.

How many moles of hydrochloric acid is present in 25cm3 of this solution?

• 0.0125

• 0.0200

• 12.5

• 20.0

The relative formula mass, Mr, of calcium carbonate, CaCO3, is 100.

What is the mass of carbon present in 100 g of calcium carbonate?

• 12 g

• 36 g

• 40 g

• 60 g

Calcium carbonate reacts with dilute hydrochloric acid according to the equation shown.

• 1 and 2

• 1 and 4

• 2 and 3

• 3 and 4

Methane, CH4, burns in the air to form carbon dioxide and water.

What is the balanced equation for this reaction?

• A

• B

• C

• D

The equation for the decomposition of magnesium nitrate is shown.

2Mg(NO3)2(s) → 2MgO(s) + 4NO2(g) + O2(g)

Which volume of gas is produced when 0.1 moles of magnesium nitrate is decomposed

completely?

• 1.2 dm3

• 4.8 dm3

• 6.0 dm3

• 8.4 dm3

The equation shows the reaction between magnesium and sulfuric acid.

[Ar: H, 1; O, 16; Mg, 24; S, 32]

Mg + H2SO4 → MgSO4 + H2

In this reaction, which mass of magnesium sulfate is formed when 6g of magnesium react with

excess sulfuric acid?

• 8

• 24

• 30

• 60