1) Define:
A) Voltmeter
B) electrodes
C) cathode
D) anode
E) electrolyte
F) non-electrolyte
G) electrolysis
2) Name three different classes of compounds which are electrolysis.
3) classify the following solutions into electrolytes (strong/weak) and non-electrolytes:
A) sugar solution
B) water (distilled)
C) common salt solution (aqueous)
D) Aqueous sodium hydroxide
E) acetic acid
F) copper sulphate solution
G) hydrochloric acid
H) lead bromide
4) Write the formula or symbols with different charges of the ions present in the following:
A) sodium hydroxide solution
B) ammonium sulphate solution
C) Iron(III) chloride solution
D) silver nitrate solution
5) Explain the following:
A) metals conduct electricity bill they are not called electrolysis.
B) Hydrogen chloride is not a conductor of electricity but its solution in water (acid hydrochloric) is a good conductor
C) Metallic ions are always at the cathode.
D) solid lead bromide is not a conductor of electricity but in the fused or molten state it is a good conductor.
E) Aluminium conducts electricity both in the solid and the liquid states.
F) Would you class graphite as a conductor or an electrolyte.
6) Explain the difference between a strong and a weak electrolyte. Give two examples of each kind in support of your answer.
7) State two difference between each of the following:
A) sodium -atoms and sodium ions.
B) chloride ions and chlorine atoms.
8)a) What is meant by the preferential discharge of ions.
B) State three factors which govern this preference.
9) Arrange the following+ve and- ve in the order they will be discharged first in preference to others:
At the cathode. At the anode
H⁺ SO²⁻₄
Mg ²⁺ Cl⁻
Ca²⁺ OH⁻
K⁺ I⁻
Cu²⁺ NO⁻₃
Na⁺
10) Name the products formed in anode and cathode of the following:
A) Acidulated water or (Dil. Sulphuric acid):
Cathode : platinum
Anode: platinum
B) copper (II) sulphate solution.
Cathode : copper
Anode: copper
C) copper (II) sulphate solution.
Cathode : platinum
Anode: platinum
D) lead bromide (molten)
Cathode : carbon
Anode: carbon
E) copper (II) chloride solution.
Cathode : copper
Anode: carbon
11) Explain the reactions which take place at the cathode and the anode during electrolysis in each of the following cases and write ionic equation to explain the reaction:
A) copper-sulphate solution using both platinum electrodes:
Reaction at the cathode--
Ionic equation --
Reaction at the cathode ---
Ionic equation ---
B) copper (II) chloride using copper cathode and carbon anode:
Reaction at the cathode--
Ionic equation --
Reaction at the cathode ---
Ionic equation----
C) Lead bromide using carbon electrodes:
Reaction at the cathode--
Ionic equation --
Reaction at the cathode ---
Ionic equation---
12) What would you observe if the electrolysis of copper sulphate solution using platinum electrodes is continued for a long time?
13) State three difference between metallic and electrolytic conductors.
14) State three important application of electrolysis.
15) What precautions would you take in electroplating an article so that the deposit may be firm and lasting.
16) Fill in the blanks:
A) Molten lead(II) bromide conducts electricity. It is called an ____. It is composed of lead_____ and bromine ____. The lead____are___ charged and are called ____. The bromine ____are____ charged and are called _____. During electrolysis the lead ___are attracted to the _____ charged electrode which is called ___ and the bromine ____are attracted towards the ____charged electrode which is called ____.
B) Aqueous solution of HCl and NaCl which conduct relatively large quantity of current are called ____electrolytes while electrolytes like acetic acid or carbonic acid which conduct comparatively very small amount of current are called ____ electrolytes as they ___ in solution.
17) Complete the following equations which show what happens at the electrodes during electrolysis.
A) 2H+ 2e⁻ = ____
B) 4OH⁻ = 2H₂O+ O₂+ ____
C) ___+ 2e⁻ = Pb.
D) Al³ + ____= Al.
E) ____= Br₂ + e⁻
F) _____+ e⁻ = Ag
G) ____= Cl₂ + 2e⁻
H) 2O²⁻ = O₂ + ______.
18) Explain the following terms in terms of loss or gain of electrons by atoms of an element:
A) oxidation
B) reduction
C) An oxidising agent
D) A reducing agent.
19) Complete the following equations and state If the particular reaction is oxidation or reduction:
A) Mg²⁺ --> Mg
B) Mg --> Mg ²⁺
C) Cl --> Cl⁻
D) S²⁻ --> S
E) Fe²⁺ --> Fe³⁺
F) Fe³⁺ --> Fe²⁺
G) 1/2 O₂ --> O²⁻
20) State which ions in the following reactions get oxidised and which get reduced.
Express in terms of loss or gain or electrons.
A) Ferrous chloride in solution is converted into ferric chloride.
2FeCl₂ + Cl₂ = 2FeCl₃.
B) Reaction between hydrogen sulphide and chlorine.
H₂S + Cl₂ = 2HCl + S
C) Carbon monoxide is passed over heated copper oxide.
CO + CuO = Cu + CO₂.
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