Question 1a

Marks: 4

a)

In a firework, solid potassium nitrate, KNO₃, decomposes to form solid potassium nitrite, KNO₂, and oxygen, O₂.

(i)

Write a balanced symbol equation for this reaction.

(ii)

Use section 6 of the data booklet to calculate the amount, in g, of potassium nitrate, KNO₃, required to make 1.5 g of oxygen. Give your answer to 2 significant figures.

Question 1b

Marks: 1

b)

Use section 2 of the data booklet to calculate the volume of gas at STP, in dm³, that is produced in the reaction outlined in part (a). Give your answer to 2 significant figures.

Question 1c

Marks: 3

c)

Potassium can form a superoxide, KO₂ (s), which will react with carbon dioxide, CO₂ (g), to produce potassium carbonate, K₂CO₃ (s) and oxygen, O₂ (g), as shown in the equation below.

4KO₂ (s) + 2CO₂ (g) → 2K₂CO₃ (s) + 3O₂ (g)

(i)

Calculate the amount, in moles, of 5.00 g of potassium superoxide. Give your answer to 3 significant figures

(ii)

Calculate the amount, in moles, and therefore volume, in dm³, of carbon dioxide which will react with the superoxide. Give your answer to 3 significant figures.

Question 1d

Marks: 1

d)

A student calculated that 4.86 g of potassium carbonate, KCO₃, should be produced during the reaction outlined in part (c), 2.61 g of potassium carbonate, KCO₃, was produced when the experiment was carried out. Calculate the percentage yield for the production of potassium carbonate. Give your answer to 2 decimal places.

Question 2a

Marks: 2

A student carried out a series of titration experiments. Their results from their experiments are shown in the table below.

Titration	Rough	1	2	3
Final reading / cm³	25.45	21.95	43.65	22.10
Initial reading / cm³	0.00	0.05	21.90	0.10
Titre / cm³	25.45	21.90	21.75	22.00

a)

Calculate the mean titre using the concordant results. Give your answer to 2 decimal places.

Key Concepts

Titrations

Question 2b

Marks: 2

b)

The student added 0.10 mol dm^-3 hydrochloric acid, HCl (aq), to the burette and performed the titration using a 25.00 cm³ sample of an unknown carbonate solution. The equation for the neutralisation reaction is shown below.

M₂CO₃(aq) + 2HCl (aq) → 2MCl (aq) + CO₂ (g) + H₂O (l)

(i)

Using your answer to part (a), calculate the amount, in moles, of hydrochloric acid used. Give your answer to 2 decimal places.

(ii)

Calculate the amount, in moles, of the aqueous carbonate solution. Give your answer to 2 decimal places.

Key Concepts

Titrations

Question 2c

Marks: 1

c)

Using your answer to part (b) (i) determine the concentration in mol dm^-3 of the aqueous carbonate. Give your answer to 2 decimal places.

Key Concepts

Titrations
Concentration Calculations

Question 2d

Marks: 4

d)

The student used 1.38 g of the unknown carbonate to make up a 250 cm³ standard solution for the titration outlined in part (a). Using section 6 of the data booklet, prove that the unknown carbonate is potassium carbonate, K₂CO₃.

Calculate the amount, in moles, of K₂CO₃ ………………………………………

Calculate the concentration in, mol dm^-3, of K₂CO₃solution …………………………………

Key Concepts

Titrations
Concentration Calculations

Question 3a

Marks: 1

a)

3.75 g of zinc oxide, ZnO (s), was added to 150 cm³of 1.00 mol dm^-3of sulfuric acid (aq) producing a salt. Write a balanced symbol equation for this reaction.

Question 3b

Marks: 3

b)

Using the equation in part (a) and section 6 of the data booklet, calculate the limiting reagent in the reaction. Give your answer to 2 significant figures.

Question 3c

Marks: 1

c)

Use your answer to part (b) and section 6 of the data booklet to calculate the amount, in grams, of the salt produced. Give your answer to 3 significant figures.

Question 3d

Marks: 1

d)

Calculate the amount, in moles, of the excess reactant left over at the end of the reaction. Give your answer to 2 decimal places.

Question 4a

Marks: 2

A sample of pure magnesium nitrate, Mg(NO₃)₂, was decomposed by heating as shown in the equation below

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

A 0.75 g sample of Mg(NO₃)₂was completely decomposed by heating.

a)

Calculate the amount, in moles, of magnesium nitrate that was decomposed. Give your answer to 2 decimal places.

Key Concepts

The Mole

Question 4b

Marks: 2

b)

Calculate the total amount, in moles, of gas produced in the reaction. Give your answer to 2 decimal places.

Key Concepts

Ideal Gas Equation

Question 4c

Marks: 2

c)

Calculate the total volume, in m³, of gas produced at 333 K and 100 kPa.

Key Concepts

Ideal Gas Equation

Question 5a

Marks: 1

a)

90 cm³ ammonia gas, NH₃(g), is combusted in oxygen, O₂(g), to produce nitrogen oxide and water, H₂O (l). What is the total volume of gases remaining when 90 cm³of ammonia is combusted completely with 50 cm³of oxygen according to the equation shown?

4NH₃ (g) + 5O₂ (g) → 4NO (g) + 6H₂O (l)

Deduce the limiting reagent for the combustion of ammonia, 90 cm³ ammonia gas, NH₃(g), is combusted in oxygen.

Key Concepts

Avogadro's Law

Question 5b

Marks: 4

b)

Calculate the total volume, in cm³, of gases remaining for the reaction in part (a).

Question 5c

Marks: 1

c)

Sketch a line on the graph below that shows the correct relationship between pressure and $\frac{1}{volume}$

1-2-ib-sl-sq-easy-q5c

Question 5d

Marks: 2

d)

At 25 ^oC and 100 kPa a gas occupies a volume of 35 dm³. Using the equation $\frac{P_{1} V_{1}}{T_{1}} = \frac{P_{2} V_{2}}{T_{2}}$ , calculate the new temperature, in ^oC, of the gas if the volume is decreased to 15 dm³ at constant pressure.

DP IB Chemistry: HL

Topic Questions

1.2 Reacting Masses & Volumes

Question 1a

Question 1b

Question 1c

Question 1d

Question 2a

Key Concepts

Question 2b

Key Concepts

Question 2c

Key Concepts

Question 2d

Key Concepts

Question 3a

Question 3b

Question 3c

Question 3d

Question 4a

Key Concepts

Question 4b

Key Concepts

Question 4c

Key Concepts

Question 5a

Key Concepts

Question 5b

Question 5c

Question 5d

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