Answer:
D. Ni²⁺
Explanation:
We know at once that the answer cannot be A or C, because Ni and Cu are already in their lowest oxidation states.
The correct answer must be either B or D.
An electrolytic cell is the opposite of a galvanic cell. In the former, the reaction proceeds spontaneously. In the latter, you must force the reaction to occur.
One strategy to solve this problem is:
- Look up the standard reduction potentials for the half reaction·
- Figure out the spontaneous direction.
- Write the equation in the reverse direction.
1. Standard reduction potentials
E°/V
Cu²⁺ + 2e⁻ ⟶ Cu; 0.3419
Ni²⁺ + 2e⁻ ⟶ Ni; -0.257
2. Galvanic Cell
We reverse the direction of the more negative half cell and add.
<u>E°/V
</u>
Ni ⟶ Ni²⁺ + 2e⁻; 0.257
<u>Cu²⁺ + 2e⁻ ⟶ Cu; </u> 0.3419
Ni + Cu²⁺ ⟶ Cu + Ni²⁺; 0.599
This is the spontaneous direction.
Cu²⁺ is reduced to Cu.
3. Electrochemical cell
<u>E°/V</u>
Ni²⁺ + 2e⁻ ⟶ Ni; -0.257
<u>Cu ⟶ Cu²⁺ + 2e⁻; </u> <u>-0.3419</u>
Cu + Ni²⁺ ⟶ Ni + Cu²⁺; -0.599
This is the non-spontaneous direction.
Ni²⁺ is reduced to Ni in the electrolytic cell.
Answer:
55.18 L
Explanation:
First we convert 113.4 g of NO₂ into moles, using its molar mass:
- 113.4 g ÷ 46 g/mol = 2.465 mol
Then we<u> use the PV=nRT formula</u>, where:
- P = 1atm & T = 273K (This means STP)
- R = 0.082 atm·L·mol⁻¹·K⁻¹
Input the data:
- 1 atm * V = 2.465 mol * 0.082atm·L·mol⁻¹·K⁻¹ * 273 K
And <u>solve for V</u>:
M has lost an electron.
It's oxidation.
Answer:
94.58 g of 
Explanation:
For this question we have to start with the reaction:
Now, we can balance the reaction:
We have the amount of 
and the amount of 
. Therefore we have to find the limiting reactive, for this, we have to follow a few steps.
1) Find the moles of each reactive, using the molar mass of each compound (
).
2) Divide by the coefficient of each compound in the balanced reaction ("2" for and "1" for ).
<u>Find the moles of each reactive</u>
<u>Divide by the coefficient</u>
<u />
The smallest values are for , so hydrogen is the limiting reagent. Now, we can do the calculation for the amount of water:
We have to remember that the molar ratio between and is 2:2 and the molar mass of is 18 g/mol.
