Redox II

Question 1

Why are experimental standard electrode potentials (Ecells) often different/incorrect to data book values? (2)

Answer 1

1. electrode potential values are for standard conditions.

2. solutions may not be concentrated enough e.g. not 1 mol/dm3.

Question 2

procedural errors when carrying out a redox titration: (3)

Answer 2

1. stirring not sufficient enough to dissolve the solid - heating may be required.
2. glassware measurements not read accurately.
3. the end point may not be clear - subjective?

Question 3

how to prepare an iron (II) solution: (5)

Answer 3

1. use mortar and pestle to crush tablets into a powder.
2. add sulphuric acid and stir to dissolve tablets.
3. filter solution into volumetric flask.
4. make sure to include the washings from the beaker.
5. make solution up to the mark with sulphuric acid/distilled water (250cm3).

Question 4

how can the end point of a titration be made easier?

Answer 4

use a white tile

Question 5

how can you ensure as much solid dissolves in titration mixture as possible?

Answer 5

stir thoroughly and possibly warm.