Q10-13: Electricity is passed through a concentrated solution of sodium chloride using inert electrodes. Sodium ions (Na+), chloride ions (Cl-), hydrogen ions (H+) and hydroxide ions (OH-) are all present in the solution.
10. To which electrodes are the ions attracted during electrolysis?
Attracted to cathode
Attracted to anode
A
Na+ and H+
Cl- and OH-
B
Na+ and Cl-
H+ and OH-
C
H+ and OH-
Na+ and Cl-
D
Cl- and OH-
Na+ and H+
11. What is the product at the negative electrode?
A. oxygen
B. sodium
C. chlorine
D. hydrogen
12. What is the test for the gas produced at the positive electrode?
A. pops with a lit splint
B. bleaches damp indicator paper
C. relights a glowing splint
D. turns limewater milky
13. After electrolysis is complete what solution would be left behind?
A. sodium chloride solution
B. sodium hydroxide solution
C. water
D. hydrochloric acid
14. Which statement about these electrolysis reactions is correct?
A. A metal is formed at the anode when molten lead(II) bromide is electrolyzed.
B. A metal is formed at the cathode when aqueous sodium chloride is electrolysed
C. A colourless gas forms at anode when molten sodium oxide is electrolyzed.
D. A brown gas forms at the cathode when molten lead(II)bromide is electrolysed
15. Copper(II)sulfate solution, CuSO4(aq), was electrolyzed using inert (carbon) electrodes.
What products are formed at each electrode during the electrolysis?
Negative electrode
Positive electrode
A
copper
Sulfur dioxide
B
copper
oxygen
C
hydrogen
Sulfur dioxide
D
hydrogen
oxygen
16. Molten sodium chloride and concentrated aqueous sodium chloride were both electrolyzed using carbon electrodes.
Which row gives the products formed at the electrodes during these experiments?
Molten sodium chloride
Concentrated aqueous sodium chloride
Anode
Cathode
Anode
Cathode
A
chlorine
sodium
chlorine
hydrogen
B
chlorine
sodium
chlorine
sodium
C
sodium
chlorine
oxygen
hydrogen
D
sodium
chlorine
hydrogen
chlorine
17. Substance X was electrolyzed.
A colourless gas formed at the anode and a metal at the cathode.
What was substance X, and which electrodes were used?
A. copper(II)sulfate solution with copper electrodes
B. molten aluminium oxide with carbon electrodes
C. concentrated aqueous sodium chloride with platinum electrodes
D. molten lead(II)bromide with carbon electrodes
18. Silver and hydrogen can both be formed by electrolysis. At which electrodes do these elements form?
silver
hydrogen
A
anode
anode
B
anode
cathode
C
cathode
anode
D
cathode
cathode
Q19-20: During the electrolysis of dilute sulfuric acid the following half-reactions occur at the electrodes:
Cathode: 2H+ + 2e-→H2
Anode: 4OH-→O2 + 2H2O + 4e-
19. At which electrode did oxidation occur? Explain how you know.
Oxidation occurs at..
Reason
A
cathode
Hydrogen ions have gained electrons
B
cathode
Hydrogen ions have lost electrons
C
anode
Hydroxide ions have gained electrons
D
anode
Hydroxide ions have lost electrons
20. What is the volume ratio of hydrogen gas to oxygen gas in this experiment?
