C1 Specimen

Question 1

Suggest one reason why electron pair repulsion theory cannot be used to predict the shape of the [CoCL4]2- ion

Answer 1

Too many electrons in d-subshell

Question 2

Explain why sodium oxide forms an alkaline solution when it reacts with water

Answer 2

O2- + H2O -> 2OH-

Question 3

There are two ways to use hydrogen as a fuel for cars. One way is in a fuel cell to power an electric motor, the other is as a fuel in an internal combustion engine.
Suggest the major advantage of using the fuel cell

Answer 3

Internal combustion wastes more energy

Question 4

A data book value for the H-H bond enthalpy is 436
Suggest one reason why this value is different from your answer to Q 4.1

Answer 4

Mean bond enthalpy not the same as actual bond enthalpy

Question 5

Suggest one environmental advantage of manufacturing methanol fuel by this reaction

Answer 5

CO2 used up in this reaction

Question 6

Explain why methanol is easy to liquiefy

Answer 6

H bonding strong enough force to hold methanol molecules together

Question 7

Suggest a suitable piece of apparatus that could be used to measure out the sodium hydroxide solution

Answer 7

Burette
Because it can deliver variable volumes

Question 8

Describe the steps you would take to determine an accurate minimum temperature that is not influenced by heat from the surroundings

Answer 8

Start clock when KCl added to water
Record temp at subsequent min for 5 mins
Plot graph vs time
Extrapolate back to time of mixing = 0