Chemistry Paper 2 (Questions)

Question 1

Answer 1

Why did we not use tangent in this instance because we were asked for mean rate of reaction - so we’ve used the dy/dx method, but 35-0 = 35 and 10-0 = 10, so we end up with 35 divided by 10.

Question 2

Answer 2

• The mass of each substance does not change But the reactants and products mass are not necessarily equal to each other - just the mass of the reactants doesnt change and the mass of the products doesnt change
• the rates of the forward reaction and reverse reaction are equal

Question 3

Answer 3

• Increases
• Decreases
• Increases

Question 4

Answer 4

• Change the temperature or
• Add a catalyst

Concentration only applies to solution and surface area only applies to solids so wouldn’t get a mark for either of these answers

Question 5

Answer 5

• Reaction has stopped OR no more gas is produced (1 mark)
• Because a reactant has been used up (1 mark)

Question 6

Answer 6

• Cu²⁺

Definition of a catalyst is something that doesnt take part in the reaction, it is not used up, so in this case it must be copper. We know from the reactivity series that copper has no reaction with dilute acids (like sulfuric acid) which is what we are using in this reaction

Question 7

What method woud we use to determine the rate of the reaction for 0.05 mol/dm³ sulfuric acid at 80
seconds.

Answer 7

• Tangent method because only have one value

Question 8

The Haber process is an example of a reversible reaction where the forward reaction is exothermic:

N_{2 (g)} + 3H_{2 (g)} ⇌ 2NH_{3 (g)}

Is the statement about the system TRUE or FALSE

The energy change of the reverse reaction is endothermic

Answer 8

TRUE

The energy change of the reverse reaction is opposite to the energy change of the forward reaction so since we are told forward reaction is exothermic reverse is opposite

Question 9

The Haber process is an example of a reversible reaction where the forward reaction is exothermic:

N_{2 (g)} + 3H_{2 (g)} ⇌ 2NH_{3 (g)}

Is the statement about the system TRUE or FALSE

The equilibrium occurs within a closed system

Answer 9

TRUE

Equilibrium only exists in a closed system

Question 10

The Haber process is an example of a reversible reaction where the forward reaction is exothermic:

N_{2 (g)} + 3H_{2 (g)} ⇌ 2NH_{3 (g)}

Is the statement about the system TRUE or FALSE

The reaction has reached completion and stopped

Answer 10

FALSE

The forward and reverse reactions continue to occur but at equal rates, with no overall change in the concentrations of reactants or products but this doesnt mean the reaction has stopped

Question 11

The Haber process is an example of a reversible reaction where the forward reaction is exothermic:

N_{2 (g)} + 3H_{2 (g)} ⇌ 2NH_{3 (g)}

Is the statement about the system TRUE or FALSE

The rate of the forward reaction is equal to the rate of the reverse reaction

Answer 11

TRUE

Question 12

Answer 12

• High temperature (around 450^oC)
• Steam or catalyst (OR Aluminium oxide = catalyst)

Question 13

Answer 13

• Greater demand for smaller molecules
• because they’re more useful and make better fuels

Question 14

Answer 14

C₃H₆

Question 15

Answer 15

C₁₂H₂₆

• Cracking breaks larger hydrocarbons down so to make C₈H₁₈ we need a hydrocarbon that has a longer chain than 8 carbons

Question 16

Answer 16

• Particulates –> Global dimming (basically means less sunlight)
• Sulfur dioxide –> Acid Rain

Question 17

Answer 17

• Carbon dioxide
• Carbon monoxide

Question 18

Answer 18

• develop fuel efficient engines
• use electric cars

Question 19

Answer 19

• Higher percentage of larger molecules

Cracking involves breaking larger molecules into smaller molecules so if we’ve got more long chain molecules - they are easier to break

Question 20

Answer 20

• Air

Made up of different gases so by the definition of a mixture its not a single element or compound

Question 21

Answer 21

• Increased
• Increased

Question 22

The Earth’s atmosphere today contains a small amount of carbon dioxide.

Why has the percentage of carbon dioxide decreased since the Earth’s early atmosphere?

Answer 22

• Formation of sedimentary rocks
• CO₂ dissolved in oceans
• Photosynthesis CO₂ is on of the reactants

Question 23

Answer 23

• Sulfur dioxide

Question 24

What are the problems caused by sulfur dioxide?

Answer 24

• Acid rain
• Respiratory problems

Question 25

Answer 25

• Alkane