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# Electrochemistry Problems

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Last minute cram for finals tonight. I found these as pertains to my weak areas, so, just to see if I am doing ok, if I am wrong, please correct me-I can probably find where I went wrong!

1. What mass of solid CaO is needed to remove the sulfur dioxide from 1.0 x 106 m3 of air having an SO2 concentration of 1.5 x 10-9 M? Assume that the reaction leading to removal of the sulfur dioxide is CaO(s) + SO2(g) CaCO3(s).

56 g
96 g
37 g
84 g

2. Calculate the equilibrium constant for the decomposition of water, 2H2O(l) 2H2(g) + O2(g) at 25oC, given that G (H2O(l)) = -237.2 kJ/mol.

0.83
6.3 × 10-84
2.5 × 10-24
1.6 × 1083

3. The equilibrium constant at 427oC for the reaction N2(g) + 3H2(g) 2NH3(g) is
Kp = 9.4 × 10-5. Calculate the value of Go for the reaction under these conditions.

-33 kJ/mol
-54 kJ/mol
54 kJ/mol
33 J/mol

4. Complete and balance the following redox equation that occurs in acidic solution using the set of smallest whole-number coefficients. What is the sum of all the coefficients in the equation?

PbO2(s) + Cl-&#8594; Pb2+ + Cl2(g) (acidic solution)

(No choices give on this one) 5

5. Complete and balance the following redox equation using the set of smallest whole-numbers coefficients. What is the sum of the coefficients?

HI + HNO3&#8594; I2 + NO (acidic solution)

5
7
14
17

6. Complete and balance the following redox equation.

Br2&#8594; BrO3- + Br- (basic solution)

The sum of the smallest whole-number coefficients is

9.
12.
18.
21.

7. Complete and balance the following redox equation using the set of smallest whole-number coefficients. Now sum the coefficients of all species in the balanced equation. (Remember the coefficients that are equal to one.)

BrO3-(aq) + Sb3+(aq) &#8594; Br-(aq) + Sb5+(aq) (acidic solution)

4.
12.
13.
17.
8.If the measured voltage of the cell Zn(s) | Zn2+(aq) || Ag+(aq) | Ag(s) is 1.37 V when the concentration of Zn2+ ion is 0.010 M, what is the Ag+ ion concentration?

2.5 M
4.0 × 10-9M
6.2 × 10-3M
6.2 × 10-5M

9.Calculate the cell emf for the following reaction at 25oC:
Ni(s) + 2Cu2+(0.010 M) &#8594; Ni2+(0.0010 M) + 2Cu+(1.0 M)

0.40 V
-0.43 V
0.43 V
0.37 V

10. A current of 0.80 A was applied to an electrolytic cell containing molten CdCl2 for 2.5 hours. Calculate the mass of cadmium metal deposited.

3.2 × 10-7 g
1.2 × 10-3 g
4.2 g
8.4 g

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#### Solution Summary

This solution explains a variety of electrochemistry problems.

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## Problems on Electrochemistry

Electrochemistry Part IV
1- When the following equation is correctly balanced in acidic solution, how many electrons are transferred?

2- What is the oxidation state of C in the CF4 molecule?

3- Which species is being reduced in the following reaction:

4- Calculate E°cell for the following redox reaction. Zn2+ (aq) + Sn2+ (aq) → Zn (s) + Sn4+ (aq)
5- A student provides a current of 2.50 amps through a solution of CaCl2 (aq) for 4.50 hours. The voltage is such that calcium metal is deposited at the cathode. What is the mass of calcium deposited?
6- What is the cell potential for the reaction Mg(s)+Fe 2+ (aq)→Mg 2+ (aq)+Fe(s) at 67 ∘ C when [Fe 2+ ]= 3.80M and [Mg 2+ ]= 0.310M.Express your answer to three significant figures and include the appropriate units.

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