Mixed Exam Questions

Question 1

Suggest one advantage of adding cyclohexane to hexane in petrol

Answer 1

Cyclohexane will burn more efficiently

Question 2

Explain what is meant by the term stereoisomers

Answer 2

Compounds with the same structural formula but a different arrangement (of atoms) in space

Question 3

Chemists have developed ways of removing hydrogen chloride from these waste gases.
Sodium hydrogencarbonate, NaHCO3(s), is frequently used in industry for this purpose.

Explain how sodium hydrogencarbonate removes hydrogen chloride.

Answer 3

Sodium hydrogencarbonate neutralises HCl

Question 4

Explain the following statements, using equations where appropriate.
Life on Earth benefits from the presence of an ozone layer.
The concentration of ozone is maintained in the ozone layer.
Compound G produces radicals which catalyse the breakdown of ozone.

Answer 4

Ozone absorbs Uv light
Maintained in equilibrium
O3 -> O2 + O

Cl. + O3 –> ClO + O2
ClO. + O –> Cl. + O2

Question 5

Radical substitution produces a mixture of organic products.

Suggest two reasons why.

Answer 5

different termination products

substitution at different positions along chain

Question 6

Waste poly(hex-1-ene) can be disposed of usefully by recycling.

State two other methods of disposing of polymers that can be beneficial to the environment.

Answer 6

Combustion for energy production

Use as organic feedstock

Question 7

How many orbitals are occupied in a silicon atom

Answer 7

8

Question 8

What is the shape around the carbon atoms in graphene

Answer 8

Trigonal Planar

Question 9

Students intends to remove the water by heating the hydrated salt
Suggest one modification that the student could make to their method to reduce the percentage error in the mass of water removed

Answer 9

Use a balance weighing to 3 or more decimal places

Question 10

The student is not sure that all the water of crystallisation has been removed
How could the student modify the experiment to be confident that all the water of crystallisation has been removed?

Answer 10

Heat the constant mass

Question 11

What conditions are needed to heat alkene into hydrocarbon

Answer 11

Hydrogen and Nickel Catalyst

Question 12

What is the reactant when h2so4/ h3po4 and heat Is used to produce alkene

Answer 12

Alcohol

Question 13

Explain why the first ionisation energy of strontium is less than the first ionisation energy of calcium

Answer 13

An extra shell is added so more shielding and less nuclear attraction. Atomic radius has increased

Question 14

What are the two equations to show how NO radicals catalyse the breakdown of ozone

Answer 14

NO. + O3 => NO2. + O2

NO2. + O => O2 + NO.

Question 15

Predict the C-O-H bond angle and explain the shape

Answer 15

104.5 degrees
Oxygen has 2 bond pairs and 2 lone pairs which repel
Lone pairs repel more than bond pairs

Question 16

State one problem with disposal of poly(2-chloropropene) by combustion

Answer 16

Can go to incomplete combustion

Chlorine is produced

Question 17

What are the tests for carbonate and sulphate

Answer 17

Add HNO3 and if there’s effervescence then carbonate is present
Add BaCl2 or Ba(No3)2 and if white precipitate then sulphate present

Question 18

Explain why first ionisation energy shows a general increase across Period 3

Answer 18

Atomic radius decreases

Nuclear Charge increases therefore greater nuclear attraction

Question 19

Explain why the use of the catalyst reduces energy demand and benefits the environment

Answer 19

Lowers the temperature

Reduces CO2 emissions

Question 20

Explain why the trend in boiling points increase in halogens

Answer 20

Number of electrons increase
More London forces
More energy required to break the intermolecular forces.

Question 21

There is a sample of ammonium bromide
Describe simple tests that would identify the cation and anion present in ammonium bromide
Include reagents, expected observations and equations

Answer 21

To test for cation - ammonium
Use a litmus paper and heat with NaOH the paper should turn from red to blue.
NH4 +OH→NH3+H2O

To test for anion - bromide
Add silver nitrate and the precipitate should change turn a cream precipitate
Ag+ + Br- => AgBr

Question 22

What is the formula for silver carbonate

Answer 22

Ag2CO3

Question 23

What are the number of electrons in the 1,2,3,4 shell

Answer 23

2
8
18
32

Question 24

Outline 2 reactions routes for preparing Ba(OH)2 from barium in the lab

Answer 24

Ba + 2H2O –> Ba(OH)2 + H2

2Ba + O2 –> 2BaO
BaO + H2O –> Ba(OH)2

Question 25

What is the equation for the reaction of Carbonate

Answer 25

2H+ + CO3 2- –> CO2 + H2O

Question 26

For dynamic equilibrium does concentration need to be equal in both forward and backward reaction

Answer 26

No

Question 27

Plan an experiment on a test tube scale that would show the trend in the reactivity of the halogens CL2, Br2, I2

Answer 27

Get three testubes with the solutions , Cl2, Br2, I2 in cyclohexane
Then add NaI to all three of the test tubes
Halogen displacement reaction should occur.
Cl2 + I- –> 2Cl- + I2 Pale green to violet
Br2 + I- –> 2Br- + I2 Orange to Violet

Question 28

What is the reagent from Haloakane to Alcohol

Answer 28

NaOH (aq)

Question 29

State the shape and bond angle for SF6

Answer 29

Shape - Octahedral

90 degrees

Question 30

A stufen plans to prepare solution of magnesium nitrate starting from magnesium nitration crystals
Describe how the student would prepare the solution, giving full details of quantities apparatus and method

Answer 30

The student would measure the weight of the crystals using a balance and to 2.d.p
Then they would dissolve the crystals in distilled water
Transfer this to a 250cm^3 volumetric flask
Rinse beaker and final washings
Fill with distilled water to the mark
Stopper and invert mixture

Question 31

When alkene becomes bromoalkane

What observation is made

Answer 31

Orange to colourless

Question 32

What is meant by the term standard solution

Answer 32

Solution of a known concentration