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Ionic theory and electrolysis questions

Ionic theory and electrolysis questions | form three Chemistry

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# Question
1

How long must a current of 4.00 A be applied to a solution ofCu_{(aq)}^{2+} to produce 2.0 grams of copper metal?

  1. 2.4 x 104s
  2. 1.5 x 103s
  3. 7.6 x 102s
  4. 3.8 x 10 2s
  5. 12 x 104s.

Multiple choices
2
  1. Define the following terms
  1. Anode
  2. Cathode
  1. State Faradays second law of electrolysis

Short answers
3

A steady current of 2.5A  was passed for 15 minutes through two different types of solutions namely copper sulphate and Silver Nitrate.

  1. Calculate the masses of copper and silver liberated
  2. From the masses in (i) What were the number of moles of each substance liberated?
  3. What is the ratio in moles of Cu and Ag liberated in whole numbers?

Mathematical Calculation
4

State three industrial application of electrolysis.


Short answers
5
  1. 289500 coulombs were required to deposit one mole of a metallic element Q from its aqueous salt solution. Calculate the valency of Q.
  2. The following experiment was used to electroplate a metallic neck chain. Study it and answer the question that follows:

Ionic theory


Mathematical Calculation
6

The ionic equation when aqueous ammonium chloride reacts with sodium hydroxide solution is represented as:

  1. 2NH^{+}_{4(aq)} + 2Cl^{-}_{(aq)}
ightarrow 2NH_{3(g)} + Cl_{2(g)} + H_{2(g)}
  2. NH^{+}_{4(aq)} + OH^{-}_{(aq)}
ightarrow NH_{3(g)} + H_{2}O_{(l)}
  3. Na^{+}_{(aq)} + Cl^{-}_{(aq)}
ightarrow NaCl_{(g)}
  4. H^{+}_{(aq)} + OH^{-}_{(aq)}
ightarrow H_{2}O_{(l)}
  5. 2NH^{+}_{4(aq)} + 2Cl^{-}_{(aq)}
ightarrow 2NH_{3(g)} + 2HCl_{(g)}.

Multiple choices
7

If a stead current of 2 amperes was passed through an aqueous solution of iron (II) sulphate for 15 minutes, then the mass of iron deposited at the cathode will be:

  1. 54 g
  2. 56 g
  3. 0.54 g
  4. 28 g
  5. 0.52 g.

Multiple choices
8

A current of 0.2 A was passed through an electrolyte for 16 minutes and 40 seconds. What is the quantity of electricity produced in coulombs?

  1. 2000 C
  2. 1000 C
  3. 200 C
  4. 0.20 C
  5. 7686 C.

Multiple choices
9

Copper obtained from copper pyrites(CuFeS_{2}) is impure for electrical wiring and has to be purified by electrolysis.
(i) Name the electrolyte and the electrodes used during electrolysis.
(ii) Write the observations that can be made during the electrolysis.


Short answers
10

How long a current of 5A should be passed through a solution of silver chloride in order to deposit 3.24 g of silver metal at the cathode? Given that, the electrochemical equivalent of silver = 1.118 	imes 10^{-3} ge^{-1} .


Mathematical Calculation