electro chem

Question 1

When aqueous solutions of iron(III) and iodide ions were mixed, iron(III) iodide cannot be produced. However, iron(II) iodide can be crystallised from an aqueous mixture of iron(II) sulfate and potassium iodide. Explain the observations.

Answer 1

(this is what shld be gg in your brain but what u write will be to find spontanity of rxn)

FeI3 cannot be produced by mixing any aqueous solutions of Fe3+ and I– ions.

Redox reaction likely occurs between Fe3+ and I– ions.

But FeI2 can be crystallised from a solution mixture of Fe2+ and I– ions.

No redox reaction occurs between Fe2+ and I– ions.

Question 2

The actual voltage of a lithium-iodine button cell is +2.80 V. Suggest why this is different from the value you have obtained from (i) (+3.58V)

Answer 2

In part (i) we assumed [ions] = 1 mol dm-3, and conditions are 25°C +1 bar.

The working conditions of the button cell may not be at standard conditions.

Question 3

Explain why methanol fuel cells are more practical than hydrogen fuel cells.

Answer 3

Methanol is a liquid under room conditions, takes up less space, more easily transported and stored than H2 gas.

Question 4

Suggest the type of bonding between the lithium atoms and the layers of carbon atoms in graphite. Explain your answer.

Answer 4

Metallic bonding. Got efoa between the lattice of lithium cations and the delocalised electrons in graphite.

Question 5

define standard electrode (redox) potential

Answer 5

Of a half cell is EMF between half cell and the standard hydrogen electrode, measured at standard conditions

Question 6

define standard cell potential

Answer 6

max potential difference between 2 half-cells under standard conditions