A Level Chemistry Exam Mistakes

Question 1

Why is the reaction between C2042- ions and MnO4- ions initially slow (topic: autocatalysis)

Answer 1

1. There is no catalyst at the start of the reaction
2. Negative ions repel each other
3. The activation energy for the reaction is high

Question 2

A solution of KMnO4 has an unknown conc , how can colorimetry be used to determine the conc of a solution

Answer 2

-Make known concs of coloured solution
-plot a graph absorbance vs conc
-read unknown concs from calibration graph

Question 3

Why are complexes different colours

Answer 3

1. Different configurations
2. Diff oxidation states
3. Diff ligands
4. Diff energies of light absorbed by d electrons
5. Diff wavelengths reflected

Question 4

Draw the structure of cis platin
State the bond angle

Answer 4

90 degs
Charge 0

Question 5

Why does [Cu(H20)6]2+ have an octahedral shape

Answer 5

Maximises separation , maximise repulsion between electron pairs