Past paper questions (paper 1)

Question 1

State the meaning of the term periodicity (1) 2019 paper 1

Answer 1

The repeating patterns / trends of the properties of elements .

Question 2

Copper (I) iodide is a white solid.
Explain why copper (I) iodide is white (2) 2019 paper 1

Answer 2

• 3d shell full
• Can’t absorb visible light
• No transition from one d orbital to another

Question 3

The sample of chromium is analysed in a TOF mass spectrometer. Give two reasons why it’s necessary to ionise the isotopes of chromium before they can be analysed in a TOF mass spectrometer (2) 2020 paper 1

Answer 3

1) Ions are accelerated by an electric field .
2) Ions create a current when hitting a detector

Question 4

State the meaning of the term enthalpy change (1)

Answer 4

Heat energy change at constant pressure

Question 5

define the mass number of an atom (1) 2021 paper 1

Answer 5

Number of protons and neutrons in the atom’s nucleus

Question 6

Explain in terms of crystal structure and bonding , why silicon (IV) oxide has a higher melting point than phosphorus (V) oxide . (4) 2021 paper 1

Answer 6

• Silicon (IV) oxide is a giant covalent structure .
• Held together by strong covalent bonds which require a lot of energy to break.
• Phosphorus (V) oxide is a simple covalent molecule.
• Breaking Van de Waals forces is easier and require a lot less energy to break.

Question 7

Give an equation for the reaction of phosphorus (V) oxide with water. Suggest a pH for the solution formed .(2) 2021 paper 1

Answer 7

Equation :
P4O10 + 6H2O => 4H3PO4
pH :
1

Question 8

An element in period 3 forms an oxide that is insoluble in water. This oxide reacts with sulfuric acid with aq potassium hydroxide . Give the formula for this oxide. Give an equation for the reaction of this oxide with sulfuric acid. (2) 2021 paper 1

Answer 8

Formula :
Al2O3
Equation :
Al2O3 + H2SO4 => Al2(SO4)3 + 3H2O

Question 9

Give the formula of a hydroxide of an element in period 3 used in medicine (1) 2021 paper 1

Answer 9

Mg(OH)2

Question 10

Identify the element in period 3 , from sodium to chlorine , that has the largest atomic radius (1) 2021 paper 1

Answer 10

Na

Question 11

Discuss the role of iron as an heterogeneous catalyst in the Haber process.
Your answer should include
• meaning of the term heterogeneous catalyst
• how iron acts as a heterogeneous catalyst
• the factors that affect the efficiency and lifetime of the catalyst

Answer 11

• A heterogeneous catalyst is when the reactants are in a different phase.
• Lowers activation energy for the reaction
• Hydrogen and nitrogen adsorb onto irons surface / active site and their bonds are weakened.
• Products desorb
• Small pellets or fine iron gives an increase surface area .
• Catalyst poisoning can happen
• Active site is blocked

Question 12

Explain why an aqueous solution containing [Fe(H2O)6]3+ ions has a lower pH than an aqueous solution containing [Fe(H2O)6]2+ ions. (3) 2021 paper 1

Answer 12

• Fe3+ has a higher charge density / smaller than Fe2+ .
• Fe3+ ions are more polarising
• More O-H bonds in the water ligands break

Question 13

State the meaning of the term electrochemical series (1) 2021 paper 1

Answer 13

Electrode potentials in numerical order.

Question 14

Give two features of a reaction in a dynamic equilibrium (2) 2022 paper

Answer 14

1) forward and reverse reactions have equal rates.
2) concentrations of reactants and products are constant

Question 15

Define the term relative atomic mass (1) 2022 paper 1

Answer 15

The average mass of an atom of an element compared to 1/12th the mass of carbon - 12

Question 16

Define the term mean bond enthalpy (2) 2022 paper 1

Answer 16

Enthalpy change to break one mole of bonds averaged over a range of molecules .

Question 17

The student rinses the burette with deionised water before filling with sodium hydroxide solution.
State and explain the effect , if any that this rinsing will have on the value of the titre. (2)

Answer 17

• titre value would increase
• Because titre solution would be more dilute

Question 18

Write an equation , including state symbols , for the reaction with an enthalpy change equal to the enthalpy of formation for iron (III) oxide. (1)

Answer 18

2Fe(s) + 3/2 O2(g) -> Fe2O3(s)

Question 19

A data book value for the H-H bond enthalpy is 436KJmol-1
Suggest one reason why this value is different from your answer to part (a) (1)

Answer 19

Mean bond enthalpy are not the same as actual bond enthalpy in CO2

Question 20

Suggest why the catalyst used in this process may become less efficient if the carbon dioxide and hydrogen contain impurities. (1)

Answer 20

Impurities block active sites

Question 21

The pollutant gas NO is found inter exhaust gases from petrol engines. Explain why NO is formed in petrol engines but is not formed when petrol burns in open air. (3)

Answer 21

NO is formed from reaction nitrogen + oxygen in air.
In high temp of engine
This provides enough activation energy to break N=- bonds

Question 22

Importance of atom economy (1)

Answer 22

Maximizes masses of reactants

Question 23

Importance of percentage yield (1)

Answer 23

Getting as much product as possible in the reaction