Consider the following reactions: 3 Ni 2+(aq) + 2Cr(OH)3 (s) + 10 OH –(aq) → 3 Ni (s) + 2 CrO4 –2 (aq) + 8 H2O (l)

A) What is the value for n for this reactions?

B) Calculate the standard Gibbs Free-Energy

C) How long does it take a current of 5 A to deposit 95 g of nickel?

For the reaction

3 Ni2+(aq) + 2 Cr(OH)3(s) + 10 OH- (aq)  →  3 Ni(s) + 2 CrO42-(aq) + 8 H2O(l) G = +87 kJ/mol

Given:

(Ni2+(aq) + 2 e- →  Ni(s)) x 3 Ered = -0.28 V

(CrO42-(aq) + 4 H2O(l) + 3 e- →  Cr(OH)3(s) + 5 OH-(aq)) x 2

3 Ni2+(aq) + 6 e- →  3 Ni(s)

2 CrO42-(aq) + 8 H2O(l) + 6 e- →  2 Cr(OH)3(s) + 10 OH-(aq)

answer: the value of enthalpy change will be -152.80 kj.

solution:

pressure = 1atm , temperature = = 298 k

given that pressure and temperature are same in both gases , the number of moles of both gases can be determined by the ideal gas equation.

according to reaction 3 moles no are reacting with 1 mol of ,then 0.49 mol of no will react with moles of ozone that is 0.16 moles of ozone. since, no is limiting reagent and is an excessive reagent.

enthalpy change for the reaction between the given volumes of the gases is :