Year 11 Paper 4: Chemistry and Physics
Covers atomic structure, bonding, quantitative chemistry, chemical changes, energy, electricity, particle model and forces.
Year 11 here means a typical teaching order, not a syllabus rule. No exam board defines what belongs to Year 11, and schools sequence the course differently. Check it against your own scheme of work before using it to decide what a class has covered.
Questions
Question 1 [4 marks]
Energy
A crane lifts a load of mass 250 kg through a height of 12 m.
Calculate the gravitational potential energy gained by the load. Use GPE = m g h, with g = 9.8 N/kg.
Question 2 [5 marks]
Quantitative Chemistry
A student dissolves 6.0 g of potassium chloride in water to make 250 cm^3 of solution.
Calculate the concentration of the potassium chloride solution, in g/dm^3.
Question 3 [5 marks]
Atomic Structure and the Periodic Table
Magnesium has three naturally occurring isotopes: magnesium-24 with an abundance of 79%, magnesium-25 with an abundance of 10% and magnesium-26 with an abundance of 11%.
Calculate the relative atomic mass of magnesium. Give your answer to 3 significant figures.
Question 4 [5 marks]
Chemical Changes
Excess magnesium ribbon is added to 50 cm^3 of hydrochloric acid of concentration 2.0 mol/dm^3: Mg + 2HCl -> MgCl2 + H2.
Calculate the maximum mass of magnesium chloride that could be produced. Relative formula mass of MgCl2 = 95.
Question 5 [5 marks]
Particle Model of Matter
The specific latent heat of vaporisation of a substance is usually much greater than its specific latent heat of fusion.
Explain, in terms of the particle model, why more energy per kilogram is needed to boil a liquid than to melt the same mass of the solid.
Question 6 [5 marks]
Forces
A car of mass 900 kg travelling at 20 m/s brakes and comes to a complete stop over a distance of 45 m.
Calculate the average braking force needed to stop the car. Use work done by the brakes = kinetic energy lost, and work done = force x distance.
Question 7 [5 marks]
Electricity
A charge of 450 C flows through a lamp when a potential difference of 12 V is applied across it, over a time of 3 minutes.
Calculate the energy transferred to the lamp, and calculate the current flowing through the lamp. Use E = Q V and Q = I t.
Question 8 [5 marks]
Quantitative Chemistry
Magnesium reacts with hydrochloric acid according to the equation Mg + 2HCl -> MgCl2 + H2.
Calculate the maximum mass of hydrogen gas that can be produced from 6.0 g of magnesium. Relative atomic masses: Mg = 24, H = 1.
Question 9 [5 marks]
Particle Model of Matter
A quantity of 167000 J of energy is used to completely melt a block of ice at 0 degrees C.
The specific latent heat of fusion of ice is 334000 J/kg.
Calculate the mass of ice that is melted by this energy. Use energy = mass x specific latent heat.
Question 10 [6 marks]
Bonding, Structure and the Properties of Matter
Nanoparticles are increasingly used in products such as suncreams, catalytic converters and medicines.
Explain why nanoparticles are useful in these applications, and describe one possible risk associated with the use of nanoparticles.
Question 11 [6 marks]
Electricity
In a circuit, a 4 ohm resistor is connected in series with a parallel combination of a 6 ohm resistor and a 3 ohm resistor. The circuit is connected to a 9 V supply.
Calculate the combined resistance of the parallel section, calculate the total resistance of the circuit, and calculate the total current supplied by the battery.
Question 12 [6 marks]
Energy
A 1.5 kg block of an unknown metal is heated from 20 degrees C to 95 degrees C using 87750 J of energy.
Calculate the specific heat capacity of the metal, in J/kg degrees C. Use change in thermal energy = m c (change in temperature).
Question 13 [6 marks]
Electricity
A thermistor is connected in series with a fixed resistor to form a potential divider circuit, used to detect a change in temperature.
Explain, in terms of the thermistor's resistance, how the potential difference across the fixed resistor changes as the temperature increases.
Question 14 [6 marks]
Energy
A homeowner wants to reduce the rate of unwanted energy transfer by heating from their house in winter.
Explain how cavity wall insulation reduces the rate of energy transfer through the walls of a house, and explain why increasing the thickness of insulation gives a smaller and smaller additional benefit as more is added.
Question 15 [6 marks]
Quantitative Chemistry
In the industrial extraction of iron, iron oxide reacts with carbon monoxide: Fe2O3 + 3CO -> 2Fe + 3CO2.
Relative formula masses: Fe2O3 = 160, CO = 28, Fe = 56, CO2 = 44.
Calculate the atom economy for the formation of iron in this reaction, by mass, giving your answer to 3 significant figures, and explain why a high atom economy is considered better for sustainable development.
Model solutions
| Question 1[4 marks] | |
|---|---|
| Answer or working | Marks |
| using GPE = m g h | M1 |
| substituting 250 x 9.8 x 12 | M1 |
| correct evaluation | M1 |
| 29400 J (29.4 kJ) | A1 |
| Question 2[5 marks] | |
|---|---|
| Answer or working | Marks |
| converting the volume to dm^3, 250 / 1000 | M1 |
| 0.25 dm^3 | A1 |
| using concentration = mass / volume | M1 |
| substituting 6.0 / 0.25 | M1 |
| 24 g/dm^3 | A1 |
| Question 3[5 marks] | |
|---|---|
| Answer or working | Marks |
| multiplying each isotope's mass by its percentage abundance | M1 |
| (24 x 79) + (25 x 10) + (26 x 11) | M1 |
| a total of 2432 | A1 |
| dividing the total by 100 | M1 |
| 24.3 | A1 |
| Question 4[5 marks] | |
|---|---|
| Answer or working | Marks |
| moles of HCl = 2.0 x (50 / 1000) | M1 |
| 0.1 mol | A1 |
| using the 2:1 mole ratio between HCl and MgCl2 from the equation | M1 |
| mass = moles x relative formula mass, 0.05 x 95 | M1 |
| 4.75 g | A1 |
| Question 5[5 marks] | |
|---|---|
| Answer or working | Marks |
| melting only requiring particles to gain enough energy to move past each other while remaining close together | B1 |
| the forces of attraction between particles being only partly overcome during melting | B1 |
| boiling requiring particles to completely overcome the forces of attraction between them | B1 |
| particles changing from being close together, as a liquid, to being far apart, as a gas | B1 |
| completely separating particles needing more energy than only partly loosening them, so vaporisation needs more energy per kilogram than fusion | B1 |
| Final answer: Vaporising completely separates particles, overcoming all the forces between them, while melting only partly loosens them, so vaporising needs more energy per kilogram | |
| Question 6[5 marks] | |
|---|---|
| Answer or working | Marks |
| using KE = 1/2 m v^2 | M1 |
| substituting 0.5 x 900 x 20^2 | M1 |
| 180000 J | A1 |
| force = work done / distance, 180000 / 45 | M1 |
| 4000 N | A1 |
| Question 7[5 marks] | |
|---|---|
| Answer or working | Marks |
| using E = Q V | M1 |
| substituting 450 x 12 | M1 |
| 5400 J | A1 |
| using I = Q / t, substituting 450 / (3 x 60) | M1 |
| 2.5 A | A1 |
| Final answer: 5400 J transferred; a current of 2.5 A | |
| Question 8[5 marks] | |
|---|---|
| Answer or working | Marks |
| moles of Mg = 6.0 / 24 | M1 |
| 0.25 mol | A1 |
| using the 1:1 mole ratio between Mg and H2 from the equation | M1 |
| mass = moles x relative formula mass, 0.25 x 2 | M1 |
| 0.5 g | A1 |
| Question 9[5 marks] | |
|---|---|
| Answer or working | Marks |
| rearranging energy = mass x specific latent heat to mass = energy / specific latent heat | M1 |
| substituting 167000 / 334000 | M1 |
| correct evaluation | M1 |
| 0.50 kg | A1 |
| stating this is equivalent to 500 g | B1 |
| Final answer: 0.50 kg (500 g) | |
| Question 10[6 marks] | |
|---|---|
| Answer or working | Marks |
| nanoparticles having a very large surface area to volume ratio compared with the same mass of bulk material | B1 |
| stating a smaller mass of material is therefore needed to have the same effect (for example as a catalyst), which can reduce cost | B1 |
| stating that in suncream, nanoparticles give more even, transparent coverage on the skin while still absorbing or blocking UV light | B1 |
| stating that in a catalytic converter, the large surface area increases the rate of the catalysed reaction | B1 |
| describing a possible risk, e.g. that because nanoparticles are so small they may be able to pass through the skin or into the lungs and bloodstream | B1 |
| stating that the long-term effects of nanoparticles on human health and the environment are not yet fully understood | B1 |
| Final answer: Nanoparticles have a very large SA:V ratio, making them effective in small quantities (e.g. suncream, catalysts), but their small size means they may enter the body and their long-term health/environmental effects are not yet fully understood | |
| Question 11[6 marks] | |
|---|---|
| Answer or working | Marks |
| using 1 / Rparallel = 1/6 + 1/3 | M1 |
| a parallel resistance of 2 ohms | A1 |
| total resistance = 4 + 2 | M1 |
| 6 ohms | A1 |
| using current = V / R | M1 |
| substituting 9 / 6 to give 1.5 A | A1 |
| Final answer: Parallel resistance 2 ohms; total resistance 6 ohms; current 1.5 A | |
| Question 12[6 marks] | |
|---|---|
| Answer or working | Marks |
| finding the temperature change, 95 - 20 = 75 degrees C | M1 |
| rearranging to c = E / (m x change in temperature) | M1 |
| substituting 87750 / (1.5 x 75) | M1 |
| evaluating 1.5 x 75 = 112.5 | M1 |
| 780 J/kg degrees C | A1 |
| stating this value could be used to identify the metal, by comparing it to known specific heat capacities | B1 |
| Question 13[6 marks] | |
|---|---|
| Answer or working | Marks |
| the resistance of a thermistor decreasing as its temperature increases | B1 |
| stating that in a series circuit, the current increases if the total resistance decreases, for a fixed supply voltage | B1 |
| stating the current through the circuit therefore increases as the temperature increases | B1 |
| stating the potential difference across the fixed resistor is proportional to the current through it, since its resistance is constant | B1 |
| stating the potential difference across the fixed resistor therefore increases as the temperature increases | B1 |
| stating this changing potential difference can be used by additional circuitry to trigger a response, such as switching on a cooling fan | B1 |
| Final answer: As temperature rises, the thermistor's resistance falls, so the circuit current rises and the potential difference across the fixed resistor increases, which can trigger a response like a fan switching on | |
| Question 14[6 marks] | |
|---|---|
| Answer or working | Marks |
| cavity wall insulation containing trapped pockets of air (or foam) within the material | B1 |
| trapped air being a poor conductor of heat, reducing energy transfer by conduction through the wall | B1 |
| trapped pockets of air also reducing energy transfer by convection, by preventing convection currents forming within the cavity | B1 |
| stating the rate of energy transfer through a wall depends on the thickness of the insulating layer | B1 |
| stating doubling the thickness of insulation approximately halves the rate of energy transfer (up to a point) | B1 |
| stating each additional layer of insulation therefore saves progressively less energy than the layer before it, giving diminishing returns | B1 |
| Final answer: Cavity wall insulation traps air, which is a poor conductor and prevents convection, reducing heat loss; but each extra layer reduces the rate of loss by a smaller amount than the last, giving diminishing returns | |
| Question 15[6 marks] | |
|---|---|
| Answer or working | Marks |
| using atom economy = (mass of desired product / total mass of all products) x 100 | M1 |
| mass of desired product (iron) = 2 x 56 | M1 |
| total mass of products = (2 x 56) + (3 x 44) | M1 |
| substituting 112 / 244 | M1 |
| 45.9% | A1 |
| explaining a high atom economy means less mass is wasted as by-products, so raw materials and energy are used more sustainably | B1 |
| Final answer: 45.9% (3 sf); a high atom economy wastes less mass as by-products, making better use of raw materials and energy | |