1) Use tabulated half-cell potentials to calculate ? G ?rxn for each of the foll

Question

1)

Use tabulated half-cell potentials to calculate ?G?rxn for each of the following reactions at 25 ?C.

Br2(l)+2Cl?(aq)?2Br?(aq)+Cl2(g)

2)

Determine the minimum volume of 3.8 M HI required to completely dissolve the sample.

3)

a- Calculate ?G?rxn and K for each of the following reactions.

The disproportionation of Mn2+(aq) to Mn(s) and MnO2(s) in acid solution at 25 ?C.
Calculate ?G?rxn.

b- Calculate K.

c- The disproportionation of MnO2(s) to Mn2+(aq) and MnO?4(aq) in acid solution at 25 ?C [The reduction potential of MnO?4(aq) to MnO2(s) is 1.68 V.]
Calculate ?G?rxn.

d- Calculate K

4) A radioactive sample contains 1.25 g of an isotope with a half-life of 3.5 days.

What mass of the isotope will remain after 5.7 days? (Assume no excretion of the nuclide from the body.)

5) A sample of F?18 has an initial decay rate of 1.6×105 /s .

How long will it take for the decay rate to fall to 2.6×103 /s ? (F?18 has a half-life of 1.83 hours.)

Explanation / Answer

1. Sol:-

Given reaction is :

Br2(l) + 2Cl- (aq) -----------> 2Br- (aq) + Cl2 (g)

Oxidation half cell reaction is :

2 Cl- (aq) ------------> Cl2 (g) + 2e- , E0oxidation = - 1.358 V

Reduction half cell reaction is :  

Br2(l) + 2e- --------------> 2 Br- , E0reduction = + 1.066 V

we know

E0cell = E0reduction +  E0oxidation

E0cell = 1.066 V -  1.358 V

E0cell = - 0.29 V

also

delta G0 = - n F E0cell

delta G0 = - 2 x 96500 C x - 0.29 V

delta G0 = + 55970 J /mol

delta G0 = + 55.970 KJ/mol

Hence delta G0 = + 55.970 KJ/mol

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.