4.7 Movement and interactions 4.7.1 Forces and motion Spec ref. Summary of the specification content Learning outcomes What most candidates should be able to do Suggested timing (hours) Opportunities to develop Scientific Communication skills Opportunities to apply practical and enquiry skills Self/peer assessment Opportunities and resources Reference to past questions that indicate success 4.7.1.1 Distance is how far an object moves. Distance does not involve direction. Distance is a scalar quantity. Displacement includes both the distance an object moves, measured in a straight line from the start point to the finish point and the direction of that straight line. Displacement is a vector quantity. Speed does not involve direction. Speed is a scalar quantity. The velocity of an object is its speed in a given direction. Velocity is a vector quantity. Define distance. Define displacement. Explain the difference between distance and displacement. Explain the difference between scalars and vectors and state which distance and displacement are. 1 Analyse both a 100 m race and a 400 m (one an oval track) race. Look at how the distance and displacement changes for each race. Discussion questions: What is the difference between distance and displacement? If I complete a complete lap of a 400 m have I gone anywhere? Investigate how the distance travelled by a person and displacement is usually different. This can be done by a modelling activity. For example, students walk 4 m in a straight line and then turn left and walk a further 5 m. What distance have they moved and what is their displacement? This can be done both mathematically and by taking direct measurements.
time, t, in seconds, s If an object moves along a straight line, how far it is from a certain point can be represented by a graph. The speed of an object can be calculated from the gradient of its distance–time graph. (HT only) If an object is accelerating, its speed at any particular time can be determined by drawing a tangent and measuring the gradient of the distance–time graph at that time. Draw and interpret distance–time graphs. Calculate the of an object from a distance–time graph. Calculate the speed of an object that is accelerating from a distance – time graph by finding the tangent to the curve at a given point then finding the gradient of the tangent. How does a sat nav predict the time taken to reach home? If a satellite is moving at 30 000 mph how far does it travel in a day, week, year? Compare the distance travelled by two trolleys moving at different speeds. Which travels the furthest in a given time? If the speed is double what will happen to the distance travelled? Compare the speeds of two or more objects, or from one object at different points, on a distance–time graph from the gradients of the lines. that the steeper the line on a distance-time graph the faster the object is travelling. MS 3b, 3c on a distance–time graph? How can the distance decrease on a graph when the distance travelled has increased? Draw distance–time graphs of a journey described by another person. Alternatively, draw a distance–time graph of your journey into school and get another person to describe the journey – peer assess to see if the description is accurate. Alternatively, you could model this outside by having students moving between certain points time
Recall and apply this equation. MS 1c, 3b, 3c Use ratios and proportional reasoning to convert units and to compute rates. WS 1.2, MS 4a, 4b, 4c, 4d, 4f Relate changes and differences in motion to appropriate distance–time, and velocity–time graphs, and interpret slopes and enclosed areas in such graphs. MS 1a, 1c, 2f Calculate average speed for non-uniform motion. and the time to do that recorded as well as the distance between the points. Then back in the classroom this data can be displayed on a distance–time graph. 4.7.1.3 (HT only) The velocity of an object is its speed in a given direction. Velocity is a vector quantity. Explain why an object travelling around a circular track may have a constant speed 0.5 Why is direction important when looking at collisions? Does a negative velocity mean that the vehicle is reversing?
When an object moves in a circle the direction of the object is continually changing. This means that an object moving in a circle at constant speed has a continually changing velocity. but a constantly varying velocity. Show that the average velocity of an object around a circular track is 0 m/s. When an object moves round a track at a steady speed why is the average velocity 0 m/s (uses idea of displacement)? 4.7.1.4 Acceleration is the rate at which the velocity of an object changes. acceleration = change in velocity ÷ time a = ∆v ÷ t acceleration, a, in metres per second squared, m/s2 change in velocity, ∆v, in metres per second, m/s time, t, in seconds, s Define acceleration. Calculate the acceleration of a vehicle when given the initial and final speed and the taken for the change in speed to occur. Rearrange the equation to find other unknown quantities. Define deceleration as negative acceleration. Explain what negative acceleration means, 0.5 Why do motorcycles have a greater acceleration than cars even though the engine is usually much smaller? Discussion questions: Why is acceleration important in a car crash? How can we find the acceleration of an object? What happens to a moving object when the acceleration becomes zero? What factors affect the deceleration of a vehicle? Investigate the acceleration of a trolley in a lab ticker tape or light gates.
An object that slows down (decelerates) has a negative acceleration. The acceleration of an object can be calculated from the gradient of a velocity–time graph. The distance travelled by an object can be calculated from the area under a graph. eg an acceleration of –1.5 m/s2. WS 1.2, MS 3b, 3c Recall and this equation. WS 1.2, MS 4a, 4b, 4c, 4d, 4f, 5c Relate changes and differences in motion to appropriate velocity– time graphs, and interpret slopes (HT only) and enclosed areas in such graphs. 4.7.1.4 cont. (HT only) The following equation applies to uniform motion: (final velocity)2 – (initial velocity)2 = 2 × acceleration × distance [v2 – u2 = 2 a s] final velocity, v, in metres per second, m/s Use the equation to find any unknown given the other values. Interpret questions to find values not specifically stated, eg starts at rest means an initial velocity of 0 m/s. 1 How does the acceleration of a skydiver change through a jump? If a skydiver opens their parachute and decelerates does this mean they go upwards as when a car decelerates it does not go backwards?
the object is moving, the object continues to move at the same speed and in the same direction. So the object continues to move at the same velocity. an object moving at a constant velocity. Explain that for an object travelling at terminal velocity the driving force(s) must equal the resistive force(s) acting on the object. What are the forces acting on a skydiver at terminal speed? Why do cars have a top speed? at motorcycles, cars and articulated lorries. 4.7.1.6 Newton’s Second Law: The acceleration of an object is proportional to the resultant force acting on the object, and inversely proportional to the mass of the object. resultant force = mass × acceleration F = m a State Newton’s Second Law. Calculate the resultant force acting on an object using the equation. Rearrange the equation to find any other unknown quantity. 0.5 Questions for students to consider: What objects accelerate? How can a car accelerate if it is moving around a circle at a steady What determines how quickly a vehicle accelerates? Why does a ball falling through a liquid have a Investigate how the mass of a trolley affects its acceleration. Use light gates or ticker tape to take accurate measurements and add mass to the trolley. Investigate how the driving force of a trolley affects its acceleration. Add more mass to the pulley to change the
force, F, in newtons, N mass, m, in kilograms, kg acceleration, a, in metres per second squared, m/s2 (HT only) The tendency of objects to continue in their state of rest or of uniform motion is called inertia. Inertial mass is a measure of how difficult it is to change the velocity of an object. Inertial mass is defined by the ratio of force over acceleration. Analyse data on vehicles to determine the acceleration when given the driving force and mass of the vehicle. Explain why two identical cars that have different loads will have different accelerations. Explain why heavier vehicles have greater stopping distances than light vehicles, assuming the same braking force. (HT only) Define inertial mass. (HT only) Explain why it is difficult to get a heavy moving object to lower acceleration than a ball falling through air? Why is it harder to turn a loaded shopping trolley than an empty one? (HT only) How does the mass of a vehicle affect its acceleration? Why do motorcycles have a greater acceleration than cars? Why do cars have a higher top speed than motorcycles even though the motorcycle has less mass? driving force. Use light gates or ticker tape to take accurate measurements and add mass to the trolley. Required practical 14: investigate the effect of varying the force on the acceleration of an object of constant mass and the effect of varying the mass of an object on the acceleration produced by a constant force. Physics AT 1, 2 and 3
p = m v momentum, p, in kilograms metre per second, kg m/s mass, m, in kilograms, kg velocity, v, in metres per second, m/s In a closed system, the total momentum before an event is equal to the total momentum after the event. This is called conservation of momentum. Calculate the momentum of an object. Rearrange the equation to find any unknown quantity. State the units of momentum. Calculate the momentum of an object given its mass, speed and direction of movement. Explain the importance of the sign for a numerical velocity in the calculation of momentum. Explain what is meant by a closed system. How can police investigators determine the of vehicles before a crash? How does an explosion conserve momentum? How do rockets take off? Carry out conservation of momentum calculations for systems involving two objects, including collisions and explosions. WS 1.2, MS 3c Recall and apply this equation. WS 1.2 Use the concept of momentum as a model to analyse an event such as a collision. spring causing the explosion. Change the mass of each trolley to see the effect on the speed at which they move apart.
on kinetic energy? Draw a graph to illustrate. 4.7.1.10 The stopping distance of a vehicle is the sum of the distance the vehicle travels during the driver’s reaction time (thinking distance) and the distance it travels under the braking force (braking distance). For a given braking force the greater the speed of the vehicle, the greater the stopping distance. The braking distance of a vehicle can be affected by wet or icy weather and poor condition of the vehicle’s brakes or tyres. A driver’s reaction time can be affected by tiredness, drugs and alcohol. Define: thinking distance braking distance stopping distance. State that the overall stopping distance of a vehicle is made up of the thinking distance plus the braking distance. Describe and explain how the speed of a vehicle affects the stopping distance, for a given braking force. Estimate the typical reaction of a person. 0.5 Discussion questions: Why should a 2-second gap be left between vehicles on the road? How will being tired affect my reaction time and thinking distance? Why does the speed of a vehicle affect the thinking distance even though it takes the same amount of time to react? How do drugs affect reaction times? How does reaction time affect thinking distance? How can reaction time be found? Investigate how changes the stopping distance using a ramp set to different heights and a sand trap at the bottom of the ramp. Record the distance the car travels in the sand trap before coming to rest. Research how the reaction time of a person can be affected by various factors including: drugs (use caffeinated drinks) distractions tiredness. clip:
Evaluate the effect of various factors on thinking distance based on given data. 4.7.1.10 cont. When a force is applied to the brakes of a vehicle, work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increases. The greater the speed of a vehicle the greater the braking force needed to stop the vehicle in a certain distance. The greater the braking force the greater the deceleration of the vehicle. Large decelerations may lead to brakes overheating and/or loss of control. Describe and explain the energy changes involved in stopping a vehicle. Explain why vehicles travelling faster have larger braking distances. 0.5 Find patterns between the speed of a vehicle and the braking distance, eg what would be the effect of doubling the speed on the braking distance and why? Explain why stopping from high speed can cause the brake pads to overheat and the brake disks to warp. WS 1.5, MS 1d (HT only) estimate the forces involved in typical situations on a public road. Discussion questions: Why does a drawing pin heat up when rubbed across a surface? Why do the rims of bicycles get hot when going down steep hills? What problems are caused by brakes overheating on bicycles and cars? Why are the brakes for a Formula 1 car not suitable for road use?
4.7.2.2 The current through a component depends on both the resistance of the component and the potential difference across the component. The greater the resistance of the component the smaller the current for a given potential difference (p.d.) across the component. potential difference = current × resistance [V = I R] potential difference, V, in volts, V current, I, in amperes, A resistance, R, in ohms, Ω Define resistance. Describe and explain how increasing the resistance in a circuit will affect the current flowing through the circuit. Use the equation to calculate the potential difference (voltage), current or resistance when given the other two values. State the correct SI units for each quantity (potential difference, current and resistance). 1 What is resistance? Why are materials with low resistance chosen for power cables? What are superconductors? Research what superconductors do and what they are made from. How can the resistance of a component be calculated using the current and potential difference? Why does increasing the voltage in a circuit also increase the current flowing through it? What is meant by resistance? Find the resistance of some electrical components using Model the effect of resistance on a circuit. You can do this with clear tubing and coloured water to act as the current. Pinch the tubing to show higher resistance. Investigate how increasing the resistance of a circuit affects the current flowing. Teachit Science resource ‘Which fuse?’
value from the colour coding on the resistor. 4.7.2.2 cont. The resistance of components such as lamps, diodes, thermistors and LDRs is not constant; it changes with the current through the component. The resistance of a filament lamp increases as the temperature of the filament increases. The current through a diode flows in one direction only. The diode has a very high resistance in the reverse direction. The resistance of a thermistor decreases as the temperature increases. Explain that in other types of resistor the value of R can change as the current changes. Explain the design and use of circuits to explore such effects – including lamps, diodes, thermistors and light-dependent resistors (LDRs). 2 Draw the V–I graphs for a filament lamp and a diode. Explain the of the resulting graph in terms of resistance and current. Draw graphs to show how the resistance of an LDR will vary with light intensity and of a thermistor with temperature. Why do the current-voltage graphs for diodes and filament lamps look different to that of an ohmic conductor? Calculate the resistance of an LDR or a thermistor the range of resistances for that component and the conditions that it is placed in. Required practical 15: use circuit diagrams to construct appropriate circuits to investigate the I–V characteristics of a variety of circuit elements including a filament lamp, a diode and a resistor at constant temperature. Physics AT 6, 7 Required practical 16: use circuit diagrams to set up and check appropriate circuits to investigate the factors affecting the resistance of electrical circuits. This should include: Teachit Science resource (19977) ‘Electricty – interpreting graphs’
the total resistance of two components is the sum of the resistance of each component. Rtotal = R1 + R2 resistance, R, in ohms, Ω Calculate the currents, potential differences and resistances in d.c. series circuits. Describe how the potential difference of the power supply is shared between the components and that the share of the potential difference a component receives depends on the resistance of that component. Calculate the resistance or two components in a circuit using Rtotal = R1 + R2 What is resistance? Use the concept of equivalent resistance. Apply knowledge of series circuits to real world applications. Students should be able to explain the design and use of d.c. series circuits for measurement and testing purposes. MS 1c, 3b, 3c, 3d Solve problems for circuits which include resistors in series using the concept of equivalent resistance. MS 1c, 3b, 3c, 3d Calculate the currents, potential differences and
resistances in d.c. series circuits. 4.7.2.3 cont. For components connected in parallel: the potential difference across each component is the same the current through the whole circuit is the sum of the currents through the separate components the total resistance of two resistors is less than the resistance of the smallest individual resistor. State that the potential difference across each component in a parallel circuit is the same. Describe how the currents in different of a parallel circuit change and give the reasons for this change. Describe the effect on the resistance of adding resistors in parallel. State that adding resistors in parallel will make the total resistance less than 1 Describe the differences between series and parallel circuits in terms of current and potential difference. Students are not required to calculate the total resistance of resistors placed in parallel. Why does adding resistors in parallel reduce the resistance of the circuit compared to adding resistors in series? How does the current vary in each loop of a parallel circuit? Calculating the total resistance of two resistors joined in parallel is not required. Investigate how the current in each loop of a parallel circuit compares to the current in the main branch of the circuit. Investigate the effect of adding two resistors in series in a simple circuit, then adding the same resistors in parallel in the same circuit. Find the resistance of resistors in parallel by experimental methods.
the lowest value resistor. 4.7.2.4 Circuit diagrams use standard symbols. Recall circuit symbols. Identify circuit symbols used in a circuit. Construct circuit diagrams standard symbols. 0.5 Ask questions such as: Why are circuit symbols used? How are the electrical components connected together to form a circuit? Where does the energy in a circuit come from? Play a game or bingo with electrical symbols. Set up simple circuits from circuit diagrams. Circuits need to include voltmeters and ammeters so that students are of how these devices are connected. 4.7.2.5 Cells and batteries supply current that always passes in the same direction. This is called direct current (d.c.). An alternating current (a.c.) is one that changes direction. In the UK a.c. supply the current changes direction 50 times per second. Describe the flow of electrons in a d.c. circuit as being in one direction only. some common sources of a direct current including cells, batteries and solar cells. 1 What is the difference between a.c. and d.c.? What are common sources of a.c. and d.c.? Research the use of a.c. and d.c. Find out why the USA used d.c. then changed to a.c. Use an oscilloscope to display a.c. and d.c. signals.
The live wire carries the alternating potential difference from the supply. The neutral wire completes the circuit. The earth wire is a safety wire to stop the appliance becoming live. The potential difference between the live wire and earth (0 V) is about 230 V. The neutral wire is at or close to earth potential (0 V). The earth wire is at 0 V; it carries a current only if there is a fault. Our bodies are at earth potential (0 V). Touching the live wire produces a large potential difference across our body. This causes a current to flow through our Describe the potential difference in the live wire with respect to earth. Describe how the earth wire acts as a safety wire and only carries a current if there is a fault. State that the resistance of the earth wire is low and that it will allow a large current to flow through it. to the three pin plugs in the UK. Find out why the top pin on some plugs, eg some mobile phone chargers, is made out of plastic. How do the fuse and wire work together to prevent electrocution? WS 1.5 Identify an electrical hazard in a context.
body, resulting in an electric shock. 4.7.2.7 is defined as the rate at which energy is transferred or the rate at which work is done. power = energy transferred ÷ time [P = E ÷ t] Power = work done ÷ time [P = W ÷ t] power, P, in watts, W energy transferred, E, in joules, J time, t, in seconds, s work done, W, in joules, J An energy transfer of 1 joule per second is equal to a power of 1 watt. Define the term power. Recall and apply these equations. 1 Evaluate the benefits and drawbacks of lower power devices such as compact fluorescent lamps (CFLs). Carry out calculations to determine power, using energy transferred divided by time and work done divided by time. WS 1.2, MS 3b, 3c Recall and apply both of these equations. Investigating Find out how much power students have by getting them to perform simple tasks. Examples could include walking up a flight of stairs, lifting masses up a known height and pulling an object across a floor. For each case the students need to know the work done and the time taken. Obtaining and presenting primary evidence: Is mechanical power the same as electrical power? Work done:
Demonstrate measuring the energy transferred to a low voltage motor as it lifts a load. Compare it to the gravitational potential energy gained by the load. 4.7.2.7 cont. The power of an electrical device is related to the potential difference across it and the current through it by the equation: power = potential difference × current [P = V I] power = (current)2 × resistance [P = I2 R] power, P, in watts, W Define power. State the equation that links power, potential difference and current. Calculate the power of an electrical appliance given the potential difference and the current. 1 Why is a 7 W energy efficient light bulb cheaper to run than a 100 W incandescent light bulb? Calculate which fuse rating would be needed in a plug for a given electrical appliance when given the power rating and the potential difference. fuse should you put into a hair drier and why? Conversion to SI units may also be required. Demonstrate a of the National Grid to show the effect of sending electrical energy at high and low potential differences.
potential difference, V, in V current, I, in amperes, A resistance, R, in ohms, Ω Evaluate whether the fuse in a given situation is suitable based on the current drawn by the appliance. WS 1.2, MS 3b, 3c Recall and apply both of these equations. 4.7.2.8 Everyday electrical appliances are designed to bring about energy transfers. The amount of energy an appliance transfers depends on how long the appliance is switched on for and the of the appliance. Describe the energy changes that are taking in a given electrical appliance – stating which energy transfers are useful and which are wasted. Describe how the amount of energy transferred depends on the time the appliance is on for and the power of the appliance. 0.5 What energy changes take place in electrical appliances? WS 1.4 Explain everyday and technological applications of science. Investigate a number of electrical appliances, either around the lab or well-known devices, eg a TV, to look at the energy transfers that occur within them. Investigate how the amount of energy transferred to an electrical appliance depends on the amount of time that it is on for by connecting the
appliance up to a joulemeter. 4.7.2.8 cont. Work is done when charge flows in a circuit. The amount of energy transferred can be calculated using the equations: energy transferred = × time [E = P t] energy transferred = charge flow × potential difference [E = Q V] energy transferred, E, in joules, J power, P, in watts, W time, t, in seconds, s charge flow, Q, in coulombs, C Describe how work is done when a charge flows in a circuit. Describe, with examples, the relationship between the power ratings for domestic electrical appliances and the changes in stored energy when they are in use. Calculate the energy transferred by an electrical appliance and rearrange the equation to find the two values. Use the equation including rearranging 1 Discussion questions: What are the charge carriers in an electric current? How does a moving charge do work? What can moving charge do?
Explain why each species has been oxidised or reduced. 4.7.3.1 cont. react with some metal carbonates to produce salts, water and carbon dioxide. The test for carbon dioxide uses an aqueous solution of calcium hydroxide (limewater). Recall that react with metal carbonates. Write equations predicting products from given reactants. Describe test to identify carbon dioxide. 1 Using common reactants, predict the products. Investigate the reactions between acids and metal carbonates. Write word and balanced symbol equations for these reactions. Video clips: 4.7.3.2 Acids are neutralised by alkalis (eg soluble metal hydroxides) and bases (eg insoluble metal hydroxides and metal oxides) to produce salts and water, and by metal carbonates to produce salts, water and carbon dioxide. The particular salt produced in any reaction between an acid and a base or alkali depends on: Define the term neutralisation. Predict products from given reactants. Use the formulae of common ions to deduce the formulae of salts. 1 Predict products from reactants. WS 1.2 Use the formulae of common ions to deduce the formulae of salts. Investigate the following reactions: + soluble metal hydroxide acid + insoluble metal hydroxide Write word and balanced symbol equations for these reactions. Teachit Science resource
or carbonate, using a Bunsen burner and a water bath or electric heater to evaporate the solution. Chemistry AT 2, 3, 4 and 6 4.7.3.3 When chemical reactions occur, energy is transferred to or from the surroundings. Energy is conserved in chemical reactions. The total amount of energy in the reaction mixture and its surroundings at the end of a chemical reaction is the same as it was at the start. An exothermic reaction is one that gives out energy. This heats up the reaction mixture. Energy then transfers to the surroundings Distinguish between exothermic and endothermic reactions on the of the temperature change of the surroundings. Evaluate uses and applications of exothermic and endothermic reactions given appropriate information. 1 Research everyday energy changes and industrial energy changes. Suggest how the type of energy change links to the use. WS 1.2 Identify examples of exothermic and endothermic reactions based on the temperature change of the reaction mixture. out simple experiments that are exothermic or endothermic, such as: hydrochloric acid and sodium hydroxide hydrochloric acid and anhydrous sodium carbonate ethanoic acid and solid ammonium carbonate Video clips: YouTube:
as the reaction mixture then cools. Neutralisation of an acid with an alkali is an example of an exothermic reaction. An endothermic reaction is one that that takes in energy. This cools the reaction mixture. Energy then transfers from the surroundings as the reaction mixture then warms up again. The reaction of citric acid and sodium hydrogen carbonate is an example of an endothermic reaction. distilled water and solid ammonium nitrate hydrochloric acid and magnesium ribbon. Investigate the temperature change when sports injury packs or cooling packs are activated. Ask questions like: produces the greatest temperature change? Required practical 18: Investigate the variables that affect the temperature changes of a series of reactions in solutions, eg acid plus metals, acid plus carbonates,
and the surface area of solid reactants increases the frequency of collisions and so increases the rate of reaction. Increasing the temperature increases the frequency of collisions and the collisions more energetic, and so increases the rate of reaction. temperature, concentration and pressure in terms of frequency and energy of collision between particles. Predict and explain the effects of changing conditions on the rate of a reaction. YouTube: 4.7.4.4 Chemical reactions can occur only when reacting particles collide with each other and with sufficient energy. The minimum amount of energy that particles must have to react is called the activation energy. Reaction profiles can be used to show the relative energies of reactants and products, the activation Explain activation energy as the energy needed for a reaction to occur. Draw simple reaction profiles (energy diagrams) for exothermic and endothermic reactions showing the relative energies of reactants 1 Define the term activation energy. Draw reaction profiles for exothermic and endothermic. Explain what the diagrams display. WS 3.2, 3.5, MS 4a Use reaction profiles to identify reactions as exothermic or endothermic. Demo, and appropriate practically investigate, the reactivity of some metals with water and acid. Use YouTube clips or let students investigate the reactivity of some other combinations.
energy and the overall energy change of a reaction. and products, the activation energy and the overall energy change, with a curved arrow to show the energy as the reaction proceeds Use reaction profiles to identify reactions as exothermic or endothermic Use findings to construct a reactivity series. Compare this to the actual reactivity series. 4.7.4.5 (HT only) During a chemical reaction: energy must be supplied to break bonds in the reactants energy is given out when bonds in the products are formed. The energy needed to break bonds and the energy given Calculate energy changes in a chemical reaction by considering bond making and bond breaking energies. 1 Calculate the energy transferred in chemical reactions. Extended writing: write instructions to another student how to calculate the energy transferred in a chemical reaction. Explain why a chemical reaction is classed as exothermic or endothermic in Research common bond energies and use these in calculation for simple reactions. Video clip YouTube:
4.7.4.6 Catalysts change the rate of chemical reactions but are not used up during the reaction. Different reactions need different catalysts. Knowledge of the names of catalysts other than those specified in the subject content is not required. Describe the characteristics of catalysts and their effect on rates of reaction. Identify catalysts in reactions. Explain catalytic action in of activation energy. 1 Define the term activation energy. Identify advantages of using catalysts in industrial reactions, eg reducing costs. Explain the effect of using a catalyst on the activation energy. WS 3.5 Identify catalysts in reactions from their effect on the rate of reaction and because they are not included in the chemical equation for the reaction. Research different catalysts and uses in industry. Research catalytic converters. Video clip YouTube: 4.7.4.7 Enzymes are important as biological catalysts which allow all the reactions in cells to occur. Enzymes are large protein molecules. The shape of an enzyme is vital for its function. Each enzyme Define the terms ‘catalyst’ and ‘enzyme’. Describe the properties of enzymes. 2 Recap KS3 work on enzymes. Demo: the action of an inorganic catalyst and catalase, using living and dead tissues, on the breakdown of hydrogen peroxide. Use the Interpret observations of the action of a catalyst and of catalase from celery, potato, fresh liver and boiled liver on hydrogen peroxide. Demo: manganese dioxide boiled liver, celery, apple or potato
has an active site with a unique shape to bind a specific substrate molecule. High temperatures and extremes of pH denature the enzyme, changing the shape of the active site. The 'lock and key' model is a simplified model of enzyme action. Different enzymes work fastest at different temperatures and pH values Explain why enzymes are specific and are denatured by high temperatures and extremes of pH. Use the lock and key theory and collision theory to explain enzyme action. observations to lead into the properties of enzymes. Watch a video clip to help to describe the action of catalase. Watch computer simulations to help make notes and explain the properties of enzymes. Make models or cut-outs to demonstrate the shape of the active site of an enzyme and the shape of the substrate(s). Demo: how the rate of the catalase reaction can be measured a gas syringe or inverted cylinder of water and timer to prepare for the Required practical next lesson. MS 1a, 1c, 1d Carry out rate calculations for chemical reactions and make estimates of simple Explore how the rate of a reaction can be measured by measuring the volume of gas given off in a given time. Calculate the rate using data obtained. Discuss how the equipment could be adapted to investigate the effect of a factor on the rate of the reaction. Make predictions and identify variables. Required practical 20: investigate the effect of pH on the rate of reaction of amylase enzyme. Students should use a continuous sampling technique to determine the time hydrogen peroxide test or small beakers goggles. Demo: living tissue hydrogen peroxide flask delivery tube gas syringe cylinder and trough
calculations without using a calculator. taken to completely digest a starch solution at a range of pH values. Iodine reagent is to be used to test for starch every 30 seconds. Temperature must be controlled by use of a water bath or electric heater. Biology AT 1, 2, and 5 MS 1a, 1c, 1d 4.7.4.8 In some chemical reactions, the products of the reaction can react to produce the original reactants. Such reactions are called reversible reactions and are represented: A + B C + D Recall that some reactions may be reversed by altering the reaction conditions. 0.5 Explain what is meant by a reversible reaction. Explain the difference between: reactions and → reactions. Practical: hydrate or dehydrate copper sulfate. Write a balanced equation for the reaction and describe the full process. Heat ammonium chloride in a test tube. Use mineral wool to Video clips: YouTube:
The direction of reversible reactions can be changed by changing the conditions. Examples include the effect of changing the temperature on the decomposition of ammonium chloride and of hydrated copper(II) sulfate. support a piece of damp pH paper half way up the tube and observe the colour change. Interpret the results (blue then red) in terms of the thermal decomposition of the ammonium chloride into ammonia and hydrogen chloride. 4.7.4.9 When a reversible reaction occurs in apparatus which prevents the escape of reactants and products, equilibrium is reached when the forward and reverse reactions occur at exactly the same rate. Recall that dynamic equilibrium occurs when the rates of forward and reverse reactions are equal. 0.5 Explain the term equilibrium and give suitable examples of when it can occur. Research examples of equilibrium reactions in industry. Video clip YouTube: 4.7.4.10 (HT only) The relative amounts of all the reactants and products at Make qualitative predictions about the effect of changes on systems at equilibrium 1 Describe Le Chatelier’s principle. Video clips: YouTube:
equilibrium depend on the conditions of the reaction. If a system is at equilibrium and a change is made to any of the conditions, then the system responds to counteract the change. The effects of changing conditions on a system at equilibrium can be predicted using Le Chatelier’s Principle. when given appropriate information. Explain the effects on equilibrium of changing conditions suitable examples. Research the work of Le Chatelier or the life of Fritz Haber. Highlight the moral ambiguity of Haber’s work. YouTube: 4.7.4.10 cont. (HT only) If the concentration of one of the reactants or products is changed, the system is no longer at equilibrium and the concentrations of all the substances change equilibrium is reached again. Interpret appropriate given data to predict the effect of a change in concentration of a reactant or product on given reactions at equilibrium. 0.5 Use data to predict the effect of concentration on equilibrium. Justify answers. WS 3.5 Interpret appropriate given data to predict the effect of a change in concentration of a reactant or product on given reactions at equilibrium.
If the concentration of a reactant is increased, more products form until equilibrium is reached again. If the concentration of a product is decreased, more reactants react until equilibrium is reached again. Suggest appropriate conditions to produce a particular product. 4.7.4.10 cont. (HT only) If the temperature of a system at equilibrium is increased: the relative amount of products at equilibrium increases for an endothermic reaction the relative amount of products at equilibrium decreases for an exothermic reaction. Interpret appropriate given data to predict the effect of a change in temperature on given reactions at equilibrium. Suggest appropriate conditions to produce a particular product. 0.5 Use data to predict the effect of temperature on equilibrium. WS 1.2 Apply the idea that if a reversible reaction is exothermic in one direction, it is endothermic in the opposite direction. Video clip YouTube:
a decrease in pressure causes the equilibrium position to shift towards the side with the larger number of molecules, as shown by the symbol equation for that reaction. 4.7.5 into ions and ions into atoms Spec ref. Summary of the specification content Learning outcomes What most candidates should be able to do Suggested timing (hours) Opportunities to develop Scientific Communication skills Opportunities to apply practical and enquiry skills Self/peer assessment Opportunities and resources Reference to past questions that indicate success 4.7.5.1 When metals react with other substances the metal atoms form positive ions. Metals can be arranged in order of their reactivity Recall and describe the reactions, if any, of potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper with 1 Draw the atomic structure of metals and the ion formed. Use to describe how the ion has been formed. Demo, and where appropriate practically investigate, the reactivity of some of the Video clips: YouTube:
in a reactivity series. The metals potassium, sodium, lithium, calcium, magnesium, zinc, iron and copper can be put in order of their reactivity from their reactions with water and dilute acids. The non-metals hydrogen and carbon are often included in the reactivity series. A more reactive metal can displace a less reactive metal from a compound. The reactions of metals with water and acids are limited to room temperature and do not or dilute acids, where appropriate, to place these metals in order of reactivity. Explain how the reactivity of metals with water or dilute acids is related to the tendency of the metal to form its positive ion. Deduce an order of reactivity of metals based on experimental results. Make links between the ability to form ions and the reactivity with water and acid. Describe what occurs in a displacement reaction, using suitable examples. Explain why displacement occurs. Compare the year of discovery of a metallic element with its position in the reactivity series. Link discoveries to new technology such as the invention of the battery. Recall and describe the reactions, if any, of potassium, sodium, lithium, calcium, magnesium, zinc, iron and metals with water and acid. Use YouTube clips or let students investigate the reactivity of the remaining combinations. Use findings to construct a reactivity series. Compare this to the actual reactivity series.
include reactions with steam. copper with water or dilute acids. WS 3.5 Deduce an order of reactivity of metals based on experimental results. WS 1.2 (HT only) Write ionic equations for displacement reactions. 4.7.5.2 When an ionic compound is melted or dissolved in water, the ions are free to move about within the liquid or solution. These liquids and solutions are able to conduct electricity and are called electrolytes. Describe electrolysis in terms of the ions present and reactions at the electrodes. Recall that metals (or hydrogen) are formed at the cathode and non-metals are formed at the in 1 Explain why solid ionic compounds cannot conduct electricity but ionic compounds can conduct electricity when melted or dissolved in water. Define the term electrolyte. Carry out the electrolysis of solutions following the RSC method. Write balanced symbol equations for these reactions. Write half equations for the reactions that occur at each electrode. Electrolysis practical Video clips: YouTube:
Passing an electric current through electrolytes causes the ions to move to the electrodes. Positively charged ions move to the negative electrode (the cathode), and negatively charged ions move to the positive electrode (the anode). Ions are discharged at the electrodes producing elements. This process is called electrolysis. When a simple ionic compound is electrolysed in the molten state using inert electrodes, the metal is produced at the cathode and the electrolysis using inert electrodes. Describe how an electric current can pass through an ionic compound. Explain what happens to positive and negative ions during electrolysis and how elements form from their ions. Predict the products of electrolysis of binary ionic compounds in the molten state. WS 1.2 (HT only) half equations for the reactions occurring at the electrodes during electrolysis. Students may be required to complete and balance supplied half equations.
is produced at the anode. 4.7.5.3 The ions discharged when an aqueous solution is electrolysed using inert electrodes depend on the relative reactivity of the elements involved. At the negative electrode (cathode), hydrogen is produced if the metal is more reactive than hydrogen. At the positive electrode oxygen is produced unless the solution contains halide ions when the halogen is produced. This happens because in the aqueous solution Predict the products of the electrolysis of aqueous solutions containing a single compound. 2 Define the term aqueous. Extended writing: describe how an aqueous solution is electrolysed. Explain why the following atoms could be produced: hydrogen oxygen. WS 1.2 (HT only) Write half equations for the reactions occurring at the electrodes during electrolysis. Students may be required to complete and balance supplied half equations. Electrolyse aqueous copper (II) sulfate following the RSC method. Write balanced half equations for the reactions that occur at both electrodes. Write a full description of this method. Required practical 21: investigate what happens when aqueous solutions are electrolysed using inert electrodes. This should be an investigation involving developing a hypothesis. RSC practical method
4.7.5.5 (HT only) Oxidation is the loss of electrons and reduction is the gain of electrons. During electrolysis, at the cathode (negative electrode), positively charged ions gain electrons and so the reactions are reductions. At the (positive electrode), negatively charged ions lose electrons and so the reactions are oxidations. Explain reduction and oxidation in terms of gain or loss of electrons. Write ionic equations for displacement reactions. Identify in a given reaction, symbol equation or half equation which species are oxidised and which are reduced. 1 Write balanced symbol equations/half equations for the displacement of metal oxides. Use these to identify which species has been oxidised or reduced. Give reasons for your answers. WS 1.2 Identify, in a reaction, symbol equation or half equation, which species are oxidised and which are reduced. Carry out simple displacement reactions. Write ionic equations for these reactions. YouTube: