Reference no: EM13385723

A saturated solution of which of the following substances in water would be the best conductor of electricity?
1. NH3
2. Hg2Cl2
3. CH4
4. HCl
5. CH3COOH

Magnesium metal is placed in contact with an underground steel storage tank to inhibit the corrosion of the tank because
1. magnesium has a lower oxidation poten-
tial than iron.
2. magnesium is cheaper than gold.
3. magnesium metal is a better reducing
agent than iron.
4. magnesium functions as the cathode in
the electrochemical cell instead of the iron.
5. magnesium has a higher reduction poten-
tial than iron.

What is K for the reaction below at room temperature?
Reaction E?
CrO2-
4 (aq) + 4H2O(l)
-> Cr(OH)3(s) + 5OH-(aq) -0.12
1. 8.2 × 10-7
2. 9.3 × 10-3
3. 1.7 × 1027
4. 7.8 × 103

Write the half reactions and the balanced equation for the galvanic cell Hg(l) |Hg2+2 (aq) ||MnO-4 (aq),Mn2+(aq),H+(aq) | Pt(s) .
What is the smallest possible integer coef- ficient of Mn2+(aq) in the combined balanced equation?

When a ruthenium chloride solution was electrolyzed for 500 s with a 120 mA current, 31 mg of ruthenium was deposited. What is the oxidation number of ruthenium in ruthenium chloride?
1. 3
2. 6
3. 1
4. 5
5. 4
6. 2

What is the average current generated in the Cu(s) |Cu2+(aq) || Fe3+(aq) | Fe(s) electrochemical cell if 50 g of Cu(s) are used up in a 24 hour period?Cu2+ + 2 e- ! Cu E?
red = +0.22 V
Fe3+ + 3 e- ! Fe E?
red = -0.04 V
1. 1.76 amp
2. 13.00 amp
3. 42.17 amp
4. 2.64 amp
5. 111.85 amp

A battery formed from the two half reactions below dies (reaches equilibrium). If [Fe2+] was 0.24 M in the dead battery, what would [Cd2+] be in the dead battery? Half reaction E?
Fe2+ -> Fe -0.44
Cd2+ -> Cd -0.40
1. 0.01 M
2. 120.3 M
3. 0.0.0005 M
4. 5.4 M

How many seconds are required to produce 4.94 mg of chromium metal from an acidic so- lution of potassium dichromate, using a cur- rent of 0.234 A?
1. 235 s
2. 157 s
3. 78 s
4. 196 s
5. 274 s
6. 118 s