Redox

Question 0

What is the oxidation number of oxygen in peroxides and in OF2?

Answer 0

-1 and +2.

Question 1

Give three disadvantages of fuel cells.

Answer 1

ELECTROLYSIS - electricity generated in power plants reliant on ffs.
NON-RENEWABLE ffs e.g. CH4 (C –> CO2)
DIFFICULT TO TRANSPORT + STORE - ULT liquefaction, high p storage systems, solid state adsorption.
PRODUCTION + PRESSURISATION - pollution.
LIMITED LIFETIME, EXPENSIVE TO REPLACE.

Question 2

What is the oxidation number of chlorine in compounds with O and Fl?

Answer 2

+1.

Question 3

what are the electrodes in hydrogen fuel cells and breathalyser fuel cells?

Answer 3

porous graphite with Ni and NiO / platinum.

Question 4

what are the electrolytes in H2 and breathalyser fuel cells?

Answer 4

solid polymer / alkaline.

Question 5

Define electrode potential.

Answer 5

maximum e.m.f. across the half cell in volts.

Question 6

define standard electrode potential.

Answer 6

e.m.f between the two half cells used measured under S.C.

Question 7

Give a definition of a standard hydrogen electrode.

Answer 7

half cell in which 1 mol dm-3 solution of H+ is in eqm with H2 (g) at 1 atm on the surface of a Pt electrode coated with Pt black at 298K.

Question 8

Above what value and below what value does a reaction go to completion or not go at all?

Answer 8

+- 0.6