Combined Science A (Gateway) · OCR J250 · Chemistry Paper 9 · Higher · June 2019
Which statement best describes an atom?
A The nucleus is small compared to the atom and contains little of the atom’s mass.
B The nucleus is large compared to the atom and contains little of the atom’s mass.
C The nucleus is small compared to the atom and contains most of the atom’s mass.
D The nucleus is large compared to the atom and contains most of the atom’s mass.
[1]
Metals can have atoms of other elements mixed with them to change their properties.
What is the name for the type of substance formed?
A Alloy
B Compound
C Solution
D Suspension
[1]
How are atoms arranged in the modern Periodic Table?
A In order of atomic number
B In order of relative atomic mass
C In order of the number of neutrons
D In order of reactivity
[1]
Which separation technique in the laboratory requires a condenser?
A Chromatography
B Crystallisation
C Filtration
D Distillation
[1]
The following table contains information about protons, neutrons and electrons.
| Particle | Relative mass | Relative charge |
| Proton | 1 | +1 |
| Neutron | 1 | –1 |
| Electron | 0.0005 | –1 |
One piece of information in the table is incorrect.
Which correction needs to be made?
A Electron charge should be 0.
B Electron mass should be 1.
C Neutron charge should be 0.
D Proton charge should be 0.
[1]
The particle model does not take into account certain information about the particles.
Which of the following does the particle model take into account?
A The size of the particles.
B The space between the particles.
C The number of particles.
D The force of attraction between the particles.
[1]
Magnesium ions react with chloride ions to form magnesium chloride.
What is the correct ionic equation for this reaction?
[1]
The table shows bond energies.
| Bond | Bond energy (kJ / mol) |
| H–H | 436 |
| Cl–Cl | 243 |
| H–Cl | 432 |
Hydrogen reacts with chlorine to form hydrogen chloride.
What is the energy change, in kJ / mol?
A –247
B –185
C +185
D +247
[1]
Which diagram correctly shows the bonding in a molecule of hydrogen fluoride?
[1]
What is the mass of 2 moles of calcium hydroxide?
A 148.2 g
B 164.1 g
C 220.1 g
D 328.2 g
[1]
A student investigates three reactions.
She wants to find out if the reactions are exothermic or endothermic.
Look at her results.
| Reaction | Start temperature (°C) | Final temperature (°C) |
| X | 21 | 25 |
| Y | 20 | 18 |
| Z | 22 | 24 |
Which reaction, X, Y or Z, is endothermic ?........
Explain your answer.
[2]
Draw a labelled reaction profile for an endothermic reaction.
Use the following labels on your reaction profile:
• products
• energy change
• activation energy.
[4]
Another student repeats the same reactions.
The student does the experiment in a polystyrene cup instead of a beaker.
Explain why using a polystyrene cup is an improvement to the method.
[2]
The reaction between iron oxide and aluminium is very exothermic.
Look at the equation for the reaction.
During this reaction the aluminium is oxidised.
Explain what is meant by the term oxidised.
[1]
Pure iron metal is produced in the reaction.
Draw a diagram to show the bonding in a metal.
Label your diagram clearly.
[3]
12* A student carries out an experiment using paper chromatography to distinguish between three substances.
Here is his method.
1. Draw a pen line half way up the paper.
2. Put a large spot of the substance to be tested onto the line.
3. Stand the paper in the solvent. The solvent should be at the same level as the spot.
4. Leave the beaker uncovered.
5. Remove the paper from the beaker before the solvent reaches the top.
He calculates the Rf value for each substance.
Look at his results.
| Substance | Distance moved by solvent (mm) | Distance moved by spot (mm) | Rf value |
| X | 95 | 78 | 1.22 |
| Y | 95 | 65 | 1.46 |
| Z | 95 | 51 | 1.86 |
His teacher noticed some mistakes with his method and his Rf values.
Describe and explain the mistakes the student has made and suggest corrections.
[6]
Aluminium, phosphorus and magnesium are all in Period 3 of the Periodic Table.
Aluminium has an atomic number of 13 and mass number of 27.
Describe the nucleus of an aluminium atom in terms of sub-atomic particles.
[2]
What is the overall charge on the nucleus of an atom of aluminium?
[1]
Which sub-atomic particles surround the nucleus?
[1]
Phosphorus has a higher atomic number and a higher mass number than aluminium.
A student says that phosphorus must be an isotope of aluminium because it has a different number of neutrons.
Is the student correct?
Tick (✓) one box.
Explain your answer.
[2]
Phosphorus can react with oxygen to form oxides. One oxide of phosphorus is called phosphorus pentoxide.
Phosphorus pentoxide has the molecular formula P4O10.
What is the empirical formula of phosphorus pentoxide?
[1]
Aluminium oxide and phosphorus pentoxide have different types of bonding.
The boiling point of aluminium oxide is 2977 °C.
The boiling point of phosphorus pentoxide is 360 °C.
What conclusion can you make about the type of bonding in each oxide?
Explain your answers.
[2]
The student is given a sample of the metal magnesium and a solution of an unknown nitrate of metal M, MNO3(aq).
The student does an experiment to identify metal M.
The student weighs the magnesium. Then the student adds the magnesium to the solution of the metal nitrate.
A displacement reaction takes place forming metal M:
The student separates the metal M and then weighs metal M.
Look at the student’s results: Mass of magnesium = 0.729 g Mass of metal M = 6.476 g
Calculate the moles of magnesium used in the experiment.
[1]
Calculate the relative atomic mass of metal M.
Give your answer to 3 significant figures.
[3]
Use your answer from (d)(ii) and the Periodic Table to identify the metal M.
[1]
Brine is the name given to the solution formed when sodium chloride, NaC l, dissolves in water.
During the electrolysis of sodium chloride solution, two ions are attracted to the negative electrode (cathode).
Identify the two ions attracted to the negative electrode (cathode).
[2]
State and explain which product is formed at the negative electrode (cathode).
[2]
Carbon is an element which can form a very wide range of compounds.
This is partly due to the number of bonds that a carbon atom can form.
State the type and maximum number of bonds that a carbon atom forms.
Maximum number of bonds........
[2]
Hex-1-ene is a carbon-based compound with the formula C6H12.
20.0 g of hex-1-ene is burned in oxygen. Carbon dioxide and water are made. Look at the equation for this reaction.
Calculate the number of molecules in 20.0 g of hex-1-ene.
Avogadro’s constant = 6.02 × 1023 mol–1
Give your answer to 3 significant figures.
Number of molecules of C6H12 =........
[4]
Hex-1-ene was burned using a spirit burner in the laboratory.
The diagram shows the spirit burner.
Burning 20.0 g of hex-1-ene should produce 62.9 g of carbon dioxide.
The actual mass of carbon dioxide produced in the reaction was 48.4 g.
What conclusion can be made about the mass of oxygen available for combustion?
[1]
The student measures how the pH of the solution changes as the acid is added.
Look at the graph of her results.
What volume of acid is needed to neutralise the alkali?
[1]
The mixture becomes less alkaline as the acid is added.
Describe how the pH of the mixture changes as the acid is added.
[2]
Explain why the mixture becomes less alkaline as the acid is added.
Use ideas about hydrogen ions and pH in your answer.
[2]
The paper as printed
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