Leaving Certificate Chemistry: Stoichiometry II

Iron reacts with chlorine as shown:

2Fe + 3Cl₂ → 2FeCl₃

The mass of iron chloride that can be obtained from 20 g of iron is...

• 58.04 g

• 55.07 g

• 59.09 g

• 57.03 g

Ethanol is produced from glucose via fermentation as shown:

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂

The mass of ethanol produced from 25 g of glucose is...

• 12.78 g

• 12.10 g

• 13.23 g

• 11.97 g

Calcium carbonate decomposes as shown:

CaCO₃ → CaO + CO₂

If 2.5 g of calcium carbonate decomposes, the volume of CO₂ produced at s.t.p. is...

• 0.56 L (560 cm³)

• 0.54 L (540 cm³⁾

• 0.52 L (520 cm³)

• 0.50 L (500 cm³)

The fact that baking powder contains NaHCO₃ which decomposes during baking to produce carbon dioxide, causes dough to rise. NaHCO₃ decomposes on heating as shown:

2NaHCO₃ → CO₂ + Na₂CO₃ + H₂O

The mass of NaHCO₃ needed to form 800 cm³ of CO₂ at s.t.p. is...

• 12 g

• 8 g

• 10 g

• 6 g

Ammonia reacts with calcium hydroxide as shown:

2NH₄Cl + Ca(OH)₂ → 2NH₃ + CaCl₂ + 2H₂O

The mass of ammonium chloride required to produce 800 cm³ of ammonia at s.t.p. is...

• 1.74 g

• 1.91 g

• 1.67 g

• 2.01 g

The classic 'growling gummy bear' demonstration is based on the decomposition of chlorate compounds. Potassium chlorate decomposes as shown:

2KClO₃ → 2KCl + 3O₂

The mass of chlorate required to produce 700 cm³ of O₂ at s.t.p. is...

• 2.01 g

• 1.97 g

• 3.01 g

• 2.55 g

Sulfur dioxide was produced from 6.3 g of sodium sulfite as shown:

Na₂SO₃ + 2HCl → 2NaCl + SO₂ + H₂O

The number of molecules of SO₂ produced at s.t.p. is...

• 3.89 x 10²² molecules

• 3.00 x 10²² molecules

• 4.01 x 10²² molecules

• 4.25 x 10²² molecules

Iron sulfide reacts with oxygen as shown:

4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂

The volume of sulfur dioxide produced at s.t.p. from 9.6 g of iron sulfide is...

• 3.01 L (3.01 dm³)

• 4.25 L (4.25 dm³)

• 3.58 L (3.58 dm³)

• 3.98 L (3.98 dm³)

Ethyne can be produced from the reaction of calcium carbide with water as shown:

CaC₂ + 2H₂O → C₂H₂ + Ca(OH)₂

The mass of calcium carbide needed to generate 350 cm³ of ethyne at s.t.p. is...

• 1.5 g

• 0.5 g

• 1 g

• 2 g

12.7 g of copper reacts with 3.2 g of sulfur to give a compound X with molecular mass of 159.

The molecular formula for compound X is...

• CuS

• CuS₂

• Cu₂S

• Cu₂S₂