Electrochemical cells

Question 1

why are the metal/graphite strips cleaned with sandpaper in a half cell?

Answer 1

to expose the surface area for reactions to occur.

Question 2

why is a salt bridge needed?

Answer 2

to complete the circuit.

Question 3

how is grease and oil removed from the metal strips?

Answer 3

using propanone

Question 4

how is a salt bridge made?

Answer 4

soak a strip of filter paper in KNO3.

Question 5

what are the standard conditions for a half cell?

Answer 5

• 1 moldm-3
• 100 kPa / 1atm
• 298K

Question 6

if a reaction is feasible emf is …..?

Answer 6

+ve

Question 7

if a reaction isn’t feasible emf is …..?

Answer 7

-ve

Question 8

Ecell =

Answer 8

reduction - oxidation

Question 9

give an example of a solution too dangerous to use at 1 moldm-3

Answer 9

AgNO3

Question 10

zinc sulphate and iron (II) sulphate are…?

Answer 10

harmful to the environment

Question 11

why must electrodes be made of inert substances?

Answer 11

so they do not interfere and react.

cannot react with water. e.g. like Mg does.

Question 12

why might experimental and theoretical values be different?

Answer 12

conditions are not standard.