11 questions · 110 marks · ≈ 2 hours
The diagram represents an atom of an element. proton neutron electron Use numbers from the box to complete the table. You may use each number once, more than once or not at all. 2 4 5 9 10 Atomic number of this atom Mass number of this atom Period number of this element Number of electrons in the 2+ ion formed from this atom
In terms of sub‑atomic particles, state a similarity and a difference for isotopes of the same element. similarity difference
This question is about apparatus used in the laboratory.
Complete the table by giving the name of each piece of apparatus and a unit used for the quantity it measures. Apparatus Name Unit 0 20 40 60 80 100
The diagram shows apparatus used to obtain pure water from sodium chloride solution by simple distillation. water out sodium chloride solution water in conical flask pure water
Explain why it is necessary for water to flow continuously in and out of the apparatus.
Describe a chemical test to show that the sodium chloride solution contains chloride ions.
Describe a physical test to show that the liquid in the conical flask is pure water.
The diagram shows a chromatogram of the food dyes in four different food colourings, A, B, C and D.
Give the letter of the food colouring that contains three different food dyes.
Give the letters of the two food colourings that contain the same dye.
Using the scale on the diagram, determine the Rf value of the dye in food colouring C. Rf =
Give a reason why the dye in food colouring D moves the furthest from the start line.
Describe how a student could obtain a chromatogram similar to the one shown in the diagram.
The diagram shows the positions of some elements in part of the Periodic Table
Give the symbol of a metal from the diagram.
Give the symbol of an element from the diagram that forms an acidic oxide.
Give a similarity in the electron configurations of Al and In.
Explain which element in the diagram is unreactive.
A teacher adds a small piece of sodium to a glass trough containing water and universal indicator. The universal indicator changes colour. The equation for the reaction is 2Na(s) + 2H₂O(l) → 2NaOH(aq) + H₂(g)
Explain the final colour of the universal indicator.
The teacher repeats the experiment with potassium instead of sodium. Give one similarity and one difference observed with potassium. similarity difference
The reaction with sodium produces 0.036 g of hydrogen gas. One mole of hydrogen gas contains 6.0 × 10²³ molecules. Calculate the number of molecules of hydrogen gas produced in the reaction with sodium. Give your answer to two significant figures. number of molecules of hydrogen gas =
This question is about metal carbonates. When heated, some metal carbonates decompose to form a metal oxide and carbon dioxide gas.
A student is given three solid metal carbonates, a timer, some limewater and this apparatus. boiling tube test tube Describe a method the student can use to find out which metal carbonate decomposes fastest when heated.
A student is given a solid metal carbonate with the formula XCO₃ X represents the symbol of a Group 2 metal. A student uses this apparatus to heat a sample of XCO₃ until it all decomposes. cotton wool plug XCO₃ The equation for the decomposition of XCO₃ is XCO₃ → XO + CO₂ The student records the mass of XCO₃ and the mass of carbon dioxide that escapes through the cotton wool plug. These are the student’s results. mass of XCO₃ = 7.40 g mass of CO₂ = 2.20 g
Give a reason why the student uses a cotton wool plug.
Calculate the amount, in mol, of carbon dioxide produced. [for carbon dioxide Mr = 44] amount of carbon dioxide = mol
Use the equation to determine the amount, in mol, of XCO₃ that decomposed. amount of XCO₃ = mol
Use the mass of XCO₃ and your answer to (b)(iii) to calculate the relative formula mass (Mr) of XCO₃ Mr of XCO₃ =
Use your answer to (b)(iv) and the Periodic Table on page 2 to determine the identity of the Group 2 metal X. Show your working. identity of X =
Silicon hydride (SiH₄) and silicon dioxide (SiO₂) both contain covalent bonds but they have different structures.
Describe the forces of attraction in a covalent bond.
Complete the diagram to show the outer shell electrons in a molecule of silicon hydride (SiH₄). H H Si H H
The diagram represents part of the structure of silicon dioxide (SiO₂). A
State how the diagram shows that the atom labelled A is oxygen, not silicon.
Silicon hydride has a simple molecular structure. Silicon dioxide has the same type of structure as diamond. Explain why silicon dioxide has a much higher melting point than silicon hydride. Refer to structure and bonding in your answer.
Silicon hydride reacts with oxygen to form silicon dioxide and water. Write a chemical equation for the reaction between silicon hydride and oxygen.
Crude oil is separated into useful fractions. Some fractions are used to make other chemicals.
crude oil → (process 1) → kerosene → (process 2) → ethene → (process 3) → chloroethene → (process 4) → poly(chloroethene)
Describe how kerosene is produced from crude oil in process 1.
C₁₂H₂₆ is present in kerosene. In process 2, C₁₂H₂₆ is cracked to produce two molecules of ethene and one molecule of another hydrocarbon.
Complete the equation for the cracking of C₁₂H₂₆ C₁₂H₂₆ → 2C₂H₄ +
Explain why cracking is a useful process in the oil industry.
This is the equation for one of the reactions that may occur during process 3. What is the name of this type of reaction?
Choose your answer
addition
combustion
decomposition
substitution
Complete the equation for the polymerisation of chloroethene in process 4.
Explain why the disposal of polymers such as poly(chloroethene) is difficult.
This question is about exothermic reactions.
A student uses this apparatus to measure the temperature increase when an excess of zinc powder is added to copper(II) sulfate solution. zinc powder 75 g copper(II) sulfate solution glass beaker polystyrene cup
Complete the word equation for the reaction. zinc + copper(II) sulfate → +
Give a reason why the student uses a polystyrene cup inside a glass beaker.
State why zinc reacts with copper(II) sulfate solution.
The temperature at the start of the reaction is 19.7 °C. The temperature at the end of the reaction is 48.3 °C. Calculate the heat energy change, in joules, for the reaction. [for the mixture, c = 4.2 J/g/°C] heat energy change = J
The reaction between zinc and silver nitrate solution is exothermic. A mass of 0.65 g of zinc is added to excess silver nitrate solution. The heat energy change is 800 J. Calculate the molar enthalpy change, ΔH, in kJ/mol. Include a sign in your answer. ΔH = kJ/mol
This is the ionic equation for the reaction between zinc and silver nitrate solution. Zn(s) + 2Ag⁺(aq) → Zn²⁺(aq) + 2Ag(s) Explain, in terms of electrons, why this is a redox reaction.
This question is about rates of reaction.
A student uses this method to investigate the rate of reaction between iron(III) nitrate solution and sodium thiosulfate solution.
Explain which is the best catalyst for the reaction.
Explain how a catalyst increases the rate of a reaction.
The rate of a reaction can also be altered by changing the temperature or by changing the concentration of solutions.
Explain, using the particle collision theory, how increasing the temperature affects the rate of a reaction.
Explain why using a solution of a lower concentration decreases the rate of reaction.
A student investigates how the electrical conductivity changes as dilute sulfuric acid is added to barium hydroxide solution.
This is the student's method.
The table shows the student's results.
| Total volume of acid added in cm3 | Electrical conductivity in arbitrary units |
|---|---|
| 0.0 | 10.0 |
| 10.0 | 8.0 |
| 20.0 | 7.2 |
| 30.0 | 4.0 |
| 40.0 | 2.0 |
| 50.0 | 0.0 |
| 60.0 | 1.4 |
| 70.0 | 2.8 |
| 80.0 | 4.2 |
| 90.0 | 5.6 |
| 100.0 | 7.0 |
Name a piece of apparatus the student could use to add 10.0 cm³ of dilute sulfuric acid to the beaker.
Plot the student’s results.
Ignoring the anomalous result, draw two lines of best fit, making sure that the two lines cross. 10.0 8.0 6.0 Electrical conductivity in arbitrary units 4.0 2.0 0.0 0 20 40 60 80 100 Total volume of acid added in cm³
Give the trend shown on the graph for the first 50 cm³ of acid added.
Suggest a mistake the student could have made to cause the anomalous result.
This is the equation for the reaction. Ba(OH)₂(aq) + H₂SO₄(aq) → BaSO₄(s) + 2H₂O(l)
When 50 cm³ of dilute sulfuric acid have been added, only barium sulfate and water are present in the mixture. Explain why this mixture does not conduct electricity. Refer to the type of bonding in barium sulfate and in water in your answer.
Name a technique the student could use to separate barium sulfate from the mixture after 100 cm³ of dilute sulfuric acid has been added.
This question is about the reduction of tungsten oxide, WO₃
A teacher uses this apparatus to reduce tungsten oxide. excess hydrogen burning hydrogen gas tungsten oxide in heat weighing boat This is the teacher’s method.
Complete the equation by adding the state symbols. WO₃(…………. . ) + 3H₂(… … … … .. ) → W(… … … … .. ) + 3H₂O(… … … … .. )
Give an addition to the method to check that the tungsten oxide has been completely reduced.
The table shows the teacher’s results. Mass in g empty weighing boat 14.72 weighing boat and tungsten oxide 17.04 weighing boat and tungsten 16.56 Use the teacher’s results to show that the empirical formula of tungsten oxide is WO₃ [for tungsten, Ar = 184 for oxygen, Ar = 16]
The teacher wears eye protection and a lab coat during the experiment. Give one other safety precaution the teacher should take.
In industry, tungsten oxide is reduced on a large scale using hydrogen. The percentage yield of tungsten is 73.5% This is the equation for the reaction. WO₃ + 3H₂ → W + 3H₂O Calculate the mass, in tonnes, of tungsten that is produced when 2784 tonnes of tungsten oxide are reacted with an excess of hydrogen. [1 tonne = 1 × 10⁶ g] [for tungsten, Ar = 184 for oxygen, Ar = 16] mass of tungsten = tonnes