Elektrokimia Practice Questions
UN (Indonesia) · UN Kimia · 151 free MCQs with instant results and detailed explanations.
151
Total
50
Easy
80
Medium
21
Hard
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Sample Questions from Elektrokimia
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Q1
Easy
What is the primary function of an electrolyte in an electrochemical cell?
A.
To provide electrical conductivity
B.
To act as an insulator
C.
To release heat during reactions
D.
To prevent corrosion
Show Answer & Explanation
Correct Answer: A
Electrolytes are essential for conducting electricity in electrochemical cells, allowing ions to move between the electrodes and enabling the cell to function properly.
Q2
Easy
In a galvanic cell, what is produced at the anode?
A.
Oxidation occurs and electrons are released
B.
Reduction occurs and electrons are gained
C.
No reaction occurs
D.
Hydrogen gas is produced
Show Answer & Explanation
Correct Answer: A
At the anode of a galvanic cell, oxidation takes place, which results in the release of electrons that flow through the circuit.
Q3
Easy
Which of the following statements about electrolysis is TRUE?
A.
It involves only oxidation reactions
B.
It is a non-spontaneous process driven by external energy
C.
It occurs spontaneously without any energy input
D.
It can only occur with solid electrodes
Show Answer & Explanation
Correct Answer: B
Electrolysis is a non-spontaneous process that requires an external source of energy to drive the chemical reactions and produce products.
Q4
Medium
What is the standard electrode potential (E°) for a half-cell reaction, given the following standard electrode potentials: Zn²⁺/Zn = -0.76 V and Cu²⁺/Cu = +0.34 V?
A.
1.10 V
B.
0.76 V
C.
-1.10 V
D.
-0.34 V
Show Answer & Explanation
Correct Answer: A
The standard electrode potential for the cell reaction can be calculated by subtracting the anode potential from the cathode potential. Here, E° = E°(Cu²⁺/Cu) - E°(Zn²⁺/Zn) = 0.34 V - (-0.76 V) = 1.10 V, making option A correct.
Q5
Medium
Which statement correctly describes the process of electrolysis in terms of ion movement?
A.
Anions move towards the cathode, and cations move towards the anode.
B.
Anions move towards the anode, and cations move towards the cathode.
C.
Both anions and cations move towards the cathode.
D.
Cations and anions do not move during electrolysis.
Show Answer & Explanation
Correct Answer: B
During electrolysis, cations are positively charged and move towards the cathode (the negative electrode), while anions are negatively charged and move towards the anode (the positive electrode). Thus, option B is correct.
Q6
Medium
Calculate the mass of copper deposited at the cathode during electrolysis if a current of 2 A is passed for 30 minutes. (Given: Atomic mass of Cu = 63.5 g/mol, 1 F = 96485 C, and copper deposits in the reaction Cu²⁺ + 2e⁻ → Cu)
A.
3.17 g
B.
6.35 g
C.
9.52 g
D.
12.70 g
Show Answer & Explanation
Correct Answer: A
Using the formula mass = (I × t × M) / (n × F), where M is the molar mass (63.5 g/mol), n is the number of electrons transferred (2), and t is the time in seconds (1800 s), the calculated mass is 3.17 g.
Q7
Medium
In a galvanic cell, which of the following conditions would increase the cell potential?
A.
Increasing the concentration of the reactants.
B.
Decreasing the temperature.
C.
Replacing the electrode material with a less reactive metal.
D.
Using a higher concentration of product than reactants.
Show Answer & Explanation
Correct Answer: A
According to the Nernst equation, increasing the concentration of reactants increases the cell potential. This is because a higher concentration drives the reaction forward, enhancing electron flow and voltage.
Q8
Hard
In a galvanic cell, if the standard reduction potential for the half-reaction Ag^+(aq) + e^- → Ag(s) is +0.80 V and for the half-reaction Cu^2+(aq) + 2e^- → Cu(s) is +0.34 V, which of the following statements is true regarding the cell's overall potential?
A.
The overall cell potential is +0.46 V.
B.
The overall cell potential is +1.14 V.
C.
The overall cell potential is -0.46 V.
D.
The overall cell potential cannot be determined.
Show Answer & Explanation
Correct Answer: B
To find the overall cell potential, we need to use the formula: E_cell = E_cathode - E_anode. Here, Ag^+ is reduced at the cathode (+0.80 V) and Cu^2+ is oxidized at the anode (+0.34 V). The overall potential is +0.80 V - (+0.34 V) = +1.14 V.
Q9
Hard
A solution of potassium dichromate (K2Cr2O7) is used as an oxidizing agent in an electrochemical reaction involving iron (Fe). If 0.1 M K2Cr2O7 reacts completely with 10 g of Fe, what is the change in oxidation state of chromium in this reaction?
A.
Chromium changes from +6 to +3.
B.
Chromium changes from +3 to +6.
C.
Chromium changes from +6 to 0.
D.
Chromium does not change oxidation state.
Show Answer & Explanation
Correct Answer: A
In potassium dichromate, chromium is in the +6 oxidation state. During the reduction process, it gets reduced to +3. Thus, the change in oxidation state of chromium is from +6 to +3.
Q10
Hard
In an electrochemical cell, the standard electrode potential of zinc (Zn) is -0.76 V and for copper (Cu) it is +0.34 V. What is the standard cell potential for a cell consisting of zinc and copper electrodes?
A.
+1.10 V
B.
-1.10 V
C.
+0.34 V
D.
-0.76 V
Show Answer & Explanation
Correct Answer: A
The standard cell potential (E°cell) is calculated using the formula E°cell = E°(cathode) - E°(anode). Here, Cu is the cathode (+0.34 V) and Zn is the anode (-0.76 V). Therefore, E°cell = 0.34 V - (-0.76 V) = 1.10 V.
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Elektrokimia — UN (Indonesia) UN Kimia Practice Questions Online
This page contains 151 practice MCQs for the chapter Elektrokimia in UN (Indonesia) UN Kimia. The questions are organized by difficulty — 50 easy, 80 medium, 21 hard — so you can choose the right level for your preparation.
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