Chemistry Grade 10 review part1: stoich and redox

What is the concentration of a solution containing 1.0g of sodium hydroxide in 250cm3 of solution?

• 0.025mol/dm3

• 0.10mol/dm3

• 0.25mol/dm3

• 1.0mol/dm3

20cm3 of ethyne, C2H2, are reacted with 500cm3 of oxygen. The equation for the reaction is

2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(l)

What is the total volume of gas remaining at the end of the reaction? (all volumes are measured at room temperature and pressure)

• 400cm³

• 450cm³

• 490cm³

• 520cm³

Three electrolysis cells are set up. Each cell has inert electrodes. The electrolytes are listed below.

cell 1 aqueous sodium chloride

cell 2 dilute sulfuric acid

cell 3 molten lead(II) bromide

In which of these cells is a gas formed at both electrodes?

• 1 and 2

• 1 and 3

• 2 only

• 3 only

The statements refer to the electrolysis of concentrated copper(II) chloride solution.

1 Electrons are transferred from the cathode to the copper(II) ions.

2 Electrons move around the circuit from the cathode to the anode.

3 Chloride ions are attracted to the anode.

4 Hydroxide ions transfer electrons to the cathode.

Which statements about the electrolysis of concentrated copper(II) chloride are correct?

• 1 and 3

• 1 and 4

• 2 and 3

• 2 and 4

The apparatus used for electrolysis is shown.

Which statement is correct?

• Copper forms at the anode in some electrolysis reactions.

• Hydrogen forms at the cathode in some electrolysis reactions.

• Oxygen forms at the cathode in some electrolysis reactions.

• The negative electrode is called the anode.

Calcium carbonate is heated. Calcium oxide and carbon dioxide gas are formed. The equation for the reaction is shown.

CaCO3 → CaO + CO2

225 kg of calcium carbonate is heated until there is no further change in mass. The yield of calcium oxide is 85 kg. What is the percentage yield?

• 37.8%

• 47.2%

• 67.5%

• 85.0%

What are the ionic half-equations for the electrode reactions during the electrolysis of concentrated aqueous sodium chloride?

• A

• B

• C

• D

Which of these reactions shows only reduction?

• Cu2+ + 2e– --> Cu

• Fe2O3 + 3CO --> 2Fe + 3CO2

• HCl + NaOH --> NaCl + H2O

• D Mg + ZnSO4 --> Zn + MgSO4

Phosphorus reacts with oxygen to form phosphorus(III) oxide as shown.

4P(s) + 3O2(g) → 2P2O3(s)

Which mass of phosphorus(III) oxide is produced from 6.2 g of phosphorus?

• 1.1 g

• 5.5 g

• 11.0 g

• 22.0 g

Which piece of apparatus is used to measure 24.8 cm3 of gas produced during a reaction?

• beaker

• conical flask

• measuring cylinder

• pipette