question1 (a) A Ni2+(aq) solution is electrolysed using a current of 6.70 A. Wha

Question

question1

(a) A Ni2+(aq) solution is electrolysed using a current of 6.70 A. What mass of Ni(s) is deposited after
3.50 days?
(b) What amperage is required to deposit 1.50 mol Ni in a period of 9.00 h?

question2

(a) Consider a sample of 1.10 mol C2H6(g) at 0 °C confined to a volume of (i) 4.20 L and (ii) 22.711 L.
For both cases, calculate the pressure of the gas using the ideal gas equation and the van der Waals
equation. The van der Waals constants for C2H6(g) are a = 556.2 kPa L2 mol-2 and b = 0.06380 L mol-1.
Calculate the compression factors, Z, for cases (i) and (ii).
(b) The critical pressure and temperature of ethane are 4.90 MPa and 32.2 °C respectively. Calculate
the reduced temperature and, for cases (i) and (ii), the reduced pressures for the real gas.

Explanation / Answer

(a) Ni2+(aq) + 2e- ----------> Ni (s)

So, 2 Faradays are requied to deposit 1 mole of Ni = 58.7 g of Ni.

Q = IT

I = 25 amp

T = 8 hours x 60 x 60 = 28800 sec

Q = 25 x 28800 = 720000 coulombs produced.

So, moles produced = 720 000 couloms/[96 500 x 3 coulombs] = 2.48 moles

Mass of Ni produced = moles x molar mass = 2.48 x 58.7g/mol = 146g

(b) So, given moles = 1.50 moles

So, Amount of electricity required = 1.5 x 96485 x 2 = 289455coulombs.

Q = IT = 289455 Coulombs = I x (9 x 60 x 60)

I = 8.9A

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