A Matter of Redox and Electrochemical

1. Known to have a redox reaction equation is as follows.

4HCl(aq) + 2S₂O₃^2-(aq) → 2S(s) + 2SO₂(g) + 2H₂O(l) + 4Cl^-(aq)

S oxidation number changed from ....

A. 0 and +2 to +4

B. +3 To 0 and +4

C. +4 To 0 and +2

D. +5 To +2 and 0

E. +6 To -2 and +4

2. The oxidation number of bromine in the compound sodium hypobromite, sodium bromit, and sodium bromate respectively ....

A. +3 +5 +7

B. +1 +5 +7

C. +1 +3 +5

D. -1 +3 +5

E. -1 +1 +3

3. The following is a redox reaction is ....

A. MgCl₂ + 2H₂O → Mg(OH)₂ +  2HCl

B. Cl₂ + SO₂ + 2H₂O → 2HCl + H₂SO₄

C. AgNO₃ + NaCl → AgCl + NaNO₃

D. CaO + H₂O → Ca(OH)₂

E.  SO₃ + 2KOH → K₂SO₄ + H₂O

4. Based on the following redox reaction equation, the price reaction coefficients a, b, c, and d respectively ....

aCu(s) + bAgNO₃(aq) → cCu(NO₃)₂(aq) + dAg(s)

A. 1, 1, 2, and 2

B. 1, 2, 1, and 2

C. 2, 1, 2, and 1

D. 2, 3, 1, and 1

E. 2, 3, 2, and 3

5.   Note the following oxidation-reduction equation.

KMnO₄(aq) + KI(aq) + H₂SO₄(aq) →  MnSO₄(aq) + I₂(aq) + K₂SO₄(aq) + H₂O(l) (not equal)

Mn oxidation number changed ....

A. +14 To +8

B. +7 To +2

C. +7 To -4

D. -1 To +2

E. -2 To +2

6. In the processing of aluminum electrolysis reactions Al₂O₃. If Al₂O₃ is electrolyzed as much as 102 kg, the resulting mass is Al ... kg. (Al = 27, O = 16)

A. 102

B. 80

C. 54

D. 30

E. 12

7. In the electrolysis of KI solution with a Pt electrode, the cathode chamber events occur in the reduction of the equation ....

A. K⁺(aq) + e → K(s)

B. K(s) → K⁺(aq) + e

C. 2H₂O(l) + 2e →  2OH^- (aq) + H₂(g)

D. 2H₂O(l) →  4H⁺ (aq) + O₂(g) + 4e

E. 2I^-(aq) →  I₂(g) + 2e

8. Materials used as electrodes in the cell battery (batteries) is ....

A. Pt and C

B. Zn and C

C. Pb and PbO2

D. Zn and Cu

E. Pb and PbO₂

9. On silver with gold plating, metal is used as the cathode is ....

A. silver

B. gold

C. copper

D. platinum

E. carbon

10. If 200 tom bauxite ore containing 51% Al₂O₃ purified, then electrolyzed the maximum weight of the metal that can be obtained is Al ... ton. (Ar Al = 27; O = 16)

a. 27

b. 51

c. 54

d. 102

 e. 108

11. Some standard potential data elements as follows.

Zn²⁺(aq) + 2e  → Zn(s) E^o = 0.76 volts

Cu²⁺(aq) + 2e → Cu(s) E^o = + 0.34 volts

Mg²⁺(aq) + 2e → Mg(s) E^o = – 2.34 volts

Cr³⁺(aq) + 3e Cr (s) E^o = – 0.74 volts

Price cell potential (E ° cell) found in most small ....

A. Zn / Zn²⁺(aq) // Cu ²⁺(aq) / Cu

B. Zn / Zn²⁺(aq) // Cr³⁺(aq) / Cr

C. Mg / Mg²⁺(aq) // Cr³⁺(aq) / Cr

D. Cr / Cr³⁺(aq) // Cu²⁺(aq) / Cu

E. Mg / Mg²⁺(aq) // Cu²⁺(aq) / Cu

12. In the electrolysis of a solution LSO4 using platinum electrodes, in the form 0.295 grams cathode metal deposition L. Electrolysis solution results can be neutralized by 50 ml of 0.230 M KOH solution The relative atomic mass of metal L is ....

a. 24

b. 40

c. 56

d. 59

e. 65

13. In the industrial area, the air can contain gases SO₂, CO₂, NO₂, O₂, N₂, CO, and H₂O. Pair of gas that can lead to corrosion is ....

A. O₂ and N₂

B. CO and N₂

C. CO and CO₂

      D. SO₂ and NO₂

E. CO and H₂O

14. Solution of AgNO₃ (Ag Ar = 108) electrolyzed with 10 amperes of electric current for 1 hour, then the mass of Ag is deposited on the cathode is ... grams.

a. 10.80

b. 40.29

c. 54.00

d. 108.00

e. 402.90

15. In the electrolysis of CuSO₄ solution using Au electrode Cu precipitates as much as 3,175 grams (Ar Cu = 63.5) at the cathode. The volume of gas that occurs at the anode when measured on the circumstances in which 5 liters of N2 gas mass 7 grams is ... liter.

a. 0.50