Redox, electrochemistry, transition elements, Hydrogen-oxygen fuel cells

Question 1

Give three different properties of transition metals which are not typical of other metals

Answer 1

(good) catalysts;
variable oxidation numbers;
form coloured compounds / coloured ions

Question 2

Transition metal physical properties

Answer 2

They are lustrous
They are hard and strong
They conduct heat and electricity

Question 3

Electrons are supplied

Answer 3

From battery / power supply / cell; [1 mark]
From negative electrode of battery to external circuit
OR
From iodide ion losing electron
OR
Oxidation of anion; [1 mark]

Question 4

Examples of inert electrode

Answer 4

graphite or platinum

Question 5

At which electrode does oxidation occur? Explain your choice.

Answer 5

anode/negative electrode and electrons lost(by hydrogen/H/H2)/electrons
move from this electrode

Question 6

OH- equation

Answer 6

1) 4OH -> O2 + H2O + 4e-
2) OH- into oxygen and water

Question 7

Molten potassium bromide give the products of electrolysis

Answer 7

Anode = Bromide
Cathode = Potassium

Question 8

Define electrolysis

Answer 8

Breaking down of an ionic compound when molten or in aqueous solution Using electricity

Question 9

Define oxidation in terms of electron transfer

Answer 9

Electron loss

Question 10

What is the role of cryolite in aluminium extraction?

Answer 10

Lowers the melting point of electrolyte
Acts as a solvent to improve conductivity