GCSE Chemistry C8 Rates and Equilibrium What are we ..., Lecture notes of Chemistry

Download GCSE Chemistry C8 Rates and Equilibrium What are we ... and more Lecture notes Chemistry in PDF only on Docsity! GCSE Chemistry C8 Rates and Equilibrium What are we learning? What knowledge, understanding and skills will we gain? What does excellence look like? What additional resources are available? How we can control and manipulate how quickly a chemical reaction takes place Knowledge  Methods for measuring rate of reaction –the reduction of reactants or the increase in products  List methods of increasing the rate of a chemical reaction  Some reactions are reversible and the symbol that represents this  Reversible reactions are exothermic in one direction and endothermic in the opposite Understanding  Selecting / evaluating methods of measuring rate of reaction  Explain why certain factors can increase or decrease the rate of a chemical reaction  Evaluation of the strengths of limitations of our abilities to alter rate of reaction  Selecting favourable conditions to push a reversible reaction in a certain direction to alter equilibrium Skills  Independently generate hypothesis that refer to the IV and DV  Make detailed predictions based on scientific theory  Identify variables with measurements and manage control variables  Write a logical method with detail on equipment resolution  Take measures to decide on repeatability and reproducibility of results  Draw complex conclusions from graphs with multiple variables and construct tangents  Draw detailed conclusions with refer to data  Suggest uncertainties in practical Confidently calculating rate of reaction at a specific point using a tangent and understanding the difference between this calculation and that of average rate. Link to previous topics in explanations which may include particle theory, activation energy, naming the type of reaction studied, predicting or naming the products, balancing equations Extended scientific explanation on why selection of certain conditions will push equilibrium in either the forward or reverse direction. BBC Bitesize Doddle – power points and quick quizzes You tube: ‘Free science lessons’ Seneca learning platform Scheme of Work 2019 - 2020 Subject: GCSE Science: C8 Rates and Equilibrium Year Group: 10 /11 Specification: AQA Combined Science Trilogy Skill focus: 2,3,4,5 and 6 Lesson No Topic & Objectives Big Question – What will students learn? Key Activities & Specialist Terminology (Do Now Task / Starter/Tasks/Plenary Planned Assessment Homework or flipped learning resources DODDLE resources Lit Num SMSC Codes C8.1 Rates of Reaction Aiming for Grade 4 LOs:  Recall a definition for rate of reaction.  Safely describe and follow a method to monitor rate of reaction.  State the units for rate of reaction What is the best unit for measuring rate of reaction? What effect could rate of reaction have on the economy? Lesson Overview Starters Predict (5 minutes) Ask students to sketch a graph of concentration against time, with lines of best fit to show how the concentration of the limiting reactant, reactant in excess, and product changes with time. Units of rate (10 minutes) Ask students what the rate of a reaction is. Supply students with the two rate formulae from the specification. Then give them different units for mass or QnA between teachers and students Written responses to questions Class discussion Completed methods for chosen practical Doddle: Rate of reaction practical quiz Rate of reaction worksheet So3 C3 Sp2 Sp9 So8 C5 So7 Aiming for Grade 6 LOs:  Explain how there can be different units for measuring rate of reaction.  Calculate the mean rate of reaction. Temperat ure  Safely complete an experiment on how temperature affects the rate of a reaction. from too much heat? What is the benefit of controlling the temperature in greenhouses? What temperature is best to run industrial processes? Language of measurement (5 minutes) Ask students to define variable, independent variable, dependent variable, control variable, valid. Method outline (10 minutes) Give students the equation for the reaction of sodium thiosulfate with hydrochloric acid, including state symbols. Ask students to suggest which method they could use to monitor the rate of this reaction. Ask students to write an outline method for this experiment. Mains The effect of temperature on rate of reaction (30 minutes) Ask students to design a suitable results table then run the practical. Encourage students to plot a graph of time taken for a set amount of carbon dioxide to be produced against temperature of reactants. Then draw conclusions consistent with results. Ask students to calculate the mean rate of reaction for each temperature. Comparison poster (10 minutes) Give students an A5 light blue piece of paper to represent a colder temperature and an A5 light pink piece of paper to represent a warmer temperature. On each piece of paper they should draw a particle diagram and explain what the rate of reaction would be and why, using collision theory. The pieces of paper could be stuck together to make a double-sided poster. Plenaries Collision theory Pictionary (10 minutes) Split the class into groups of six. Assign each student in the group one of the following phrases: increase temperature, decrease temperature, collision theory, collision, activation energy, rate of reaction. In small groups, each student takes it in turn to try and draw their phrase with an image without words or symbols. The rest of the group have to guess the phrase. Data handling (5 minutes) Hydrogen peroxide decomposes into oxygen and water. Ask students to write an equation for this reaction and identify the independent and dependent variables. Students sketch a graph which Written responses to questions Plotted graph for practical data Class discussion the rate of reaction animation C3 Sp2 Sp9 C8 C5 So7 Aiming for Grade 6 LOs:  Use collision theory to explain how changing temperature alters the rate of reaction. Calculate mean rates of reaction. Aiming for Grade 8 LOs:  Use a graph to calculate the rate of reaction at specific times in a chemical reaction.  Calculate 1 / t and plot a graph with a more meaningful line of best fit. would allow them to calculate the mean rate of reaction and the rate of reaction at specific points. C8.4 The Effect of Concentr ation and Pressure Aiming for Grade 4 LOs:  Describe how changing concentration affects the rate of reaction.  Describe how changing pressure affects the rate of gas phase reactions. How can we crush a can without touching it? Are the effects of pressure underrated because we can’t see them? Why is the use of public transport banned in times of pandemics – how does this link to this topic? Lesson Overview Starters Gas pressure (5 minutes) Demonstrate the egg in a conical flask trick. Hard boil an egg and take the shell off. Then light a splint and put it into a 250 cm3 conical flask, quickly put the egg into the top of the flask so that it seals the aperture. Ask students to explain their observations. Bringing ideas together (10 minutes) Arrange students into small groups. Then ask them to make a visual summary to consolidate their knowledge of rate of reaction in terms of collision theory and changing conditions. Give students sticky notes and ask them to write key terms such as collision, collision theory, temperature, pressure, concentration, surface area, and rate of reaction. Students should then stick the notes on sugar paper and, using marker pens, add arrows and text on the arrows to generate sentences connecting pairs of key terms. Mains The effect of concentration on rate of reaction (40 minutes) Students investigate how concentration affects the rate of reaction. They should write a prediction which includes what they think will happen and explain their thoughts using collision theory. Students can carry out either practical for this required practical. Ensure students have time to repeat tests so that you have a set of repeat data for each acid concentration to check precision and improve accuracy. Encourage students to comment on how the experiment was made a fair test and to draw conclusions consistent with their graphical results, including calculating the mean rate of reaction. Students should also discuss the quality of the data collected and explain improvements that could be made to their investigation. Plenaries QnA between teachers and students Written responses to questions Class discussion Practical task completed Doddle: How does concentration affect the rate of reaction animation So3 C3 Sp2 C2 Sp9 C5 So7 Aiming for Grade 6 LOs:  Use collision theory to explain how changing concentration or pressure alters the rate of reaction.  Calculate mean rates of reaction.  Explain how to change gas pressure. Aiming for Grade 8 LOs:  Interpret a rate of reaction graph, including calculating the rate of reaction at specific times in a chemical reaction.  Explain why changing pressure has no effect on the rate of reaction for some reactions.  Justify quantitative predictions and evaluate in detail their investigation into the effect of concentration on rate of reaction. Effect of concentration and pressure (10 minutes) Students identify whether particle diagrams show high concentration and pressure or loconcentration and pressure. They then complete a paragraph to describe the effect of concentration and pressure on rate of reaction. Oxidation (5 minutes) Students write an equation to represent the reaction between iron and oxygen. Ask students to predict, including referring to collision theory, their observation of iron wool burning in air and then in a gas jar of oxygen. C8.5 The Effect of Catalysts Aiming for Grade 4 LOs:  Define a catalyst  Describe how adding a catalyst affects the rate of reaction.  Describe and carry out a method to safely investigate which catalyst is best for a reaction. Should catalysts be free for developing countries? Should the use of catalysts be encouraged to better protect the planet from pollution? Lesson Overview Starters Reaction profiles (5 minutes) Draw an exothermic reaction profile diagram for a generic reaction. Then ask students to predict the shape of the reaction profile if a catalyst was added. Use question and answer to build up the correct diagram on the board by using volunteers to modify the diagram. Factors that affect rates (10 minutes) Ask one student to give a reaction condition that affects the rate of a reaction. Ask another student to explain what effect this condition has. Go around the class, taking the time to check for, and correct, any misconceptions. Then ask students to explain the effect a catalyst has on a reaction. Then use the interactive to introduce catalysis and the effect catalysts have on the rate of a reaction. Mains Investigating catalysis (40 minutes) Students investigate how different catalysts affect the decomposition of hydrogen peroxide. Use the catalysts manganese(IV) dioxide, potassium iodide, and the enzyme catalase (found in raw liver, potatoes, and celery). Students record their results in a table, then display them on the same graph. Explain that catalysts provide an alternative reaction pathway that has a lower activation energy. Plenaries QnA between teachers and students Written responses to questions Class discussion Using catalyst practical completed safely Doddle: AQA Catalyst mini quiz So3 C3 Sp2 Sp9 C8 C5 So7 Aiming for Grade 6 LOs:  Use collision theory to explain how adding a catalyst alters the rate of reaction.  Explain, with an example, the industrial use of a catalyst.  Calculate the mean rate of reaction. Aiming for Grade 8 LOs:  Use a reaction profile diagram to explain in detail the effect of adding a catalyst.  Justify the use of catalysts in industry and in household products.  Explain what an enzyme is and how it works. Aiming for Grade 6 LOs:  Use collision theory to explain how adding a catalyst alters the rate of reaction.  Explain, with an example, the industrial use of a catalyst. change in each step, and what simple laboratory test this reversible reaction could be used for. Plenaries Finish the sentence (5 minutes) Students use the interactive to complete the following sentences. • A ⇋ in an equation shows (a reversible reaction) • In a reversible reaction, reactants make products (and products make reactants under the same conditions) • In a reversible reaction, if the forward reaction is exothermic (the reverse reaction will be endothermic) • The hydration of copper sulfate is (a reversible chemical reaction that can be used as a test for water) Desiccator (10 minutes) Show students a desiccator. Explain that there is a drying agent such as silica gel below the mesh and chemicals are put in the sealed vessel to dry out or to remain in a dry environment. However, the gel is often impregnated with anhydrous copper sulfate. Ask students to suggest why this is so and how this could help a laboratory technician. C8.8 Dynamic Equilibriu m Aiming for Grade 4 LOs:  Define a dynamic equilibrium  Describe a closed system Can we manipulate reversible reactions so they only go in one direction? How can we make fertiliser if Lesson Overview Starters Dynamic equilibrium (5 minutes) Interactive where students complete a paragraph to summarise reversible reactions and the energy changes involved. Modelling (10 minutes) Split the class into groups of three, give each group a tray and 20 small similar objects (such as balls, pencils, rubbers). Ask students to put 10 objects in the tray and 10 objects on the table. One person from the group should take objects out of the tray, and QnA between teachers and students Written responses to questions Class discussion Doddle: GW Equilibrium mini quiz So3 C3 Sp2 C8 Sp9 C5 So7 Aiming for Grade 6 LOs:  Describe how to achieve dynamic equilibrium.  Describe how rate of the forward reaction compares to rate of the backward reaction in a dynamic equilibrium. Describe Le Chatelier’s Principle. Aiming for Grade 8 LOs:  Explain dynamic equilibrium.  Explain why the concentration of chemicals in a dynamic equilibrium remains constant. Predict the effect on the rate of forward and reverse reactions by applying the Le Chatelier’s Principle when the conditions of a dynamic equilibrium are changed. the reaction is reversible? the second person should put objects back. The third person should keep time, so that both people work at the same rate. Run the model for a short time. Then ask students to relate this model to a reversible reaction. Mains Dynamic equilibrium and Le Chatelier’s Principle (40 minutes) Describe to students the escalator model for dynamic equilibrium. Imagine that you are walking up an escalator that is going down. If your pace matches the movement of the escalator your relative position stays the same, even though both you and the escalator are moving. You may wish to refer students to Figure 1 of the student book. Then ask small groups of students to generate their own model to explain dynamic equilibrium and to illustrate the features of a dynamic equilibrium. If time, students could demonstrate their models. Introduce Le Chatelier’s Principle to students. They should then go through worked examples of several equilibrium systems for reversible reactions already met in the specification or in the lessons so far. They should use the worked examples to explain how changing the concentration of a reactant or product would affect the rates of each reaction and therefore the yield of the product. Plenaries Fizzy water (5 minutes) Show students a bottle of fizzy water and shake it. Ask students to explain how this is a dynamic equilibrium (carbon dioxide dissolves in and is released from the water). Carefully open the top over the sink. Ask students to explain their observations (the open system means that the carbon dioxide escapes into the atmosphere). Think, pair, square on catalysts (10 minutes) Ask students to predict the effect on dynamic equilibrium of adding a catalyst. They then share their ideas in a pair and finally as a whole table. Encourage each table to feed back and use question and answer to guide the class so that they Using exam questions to demonstrate understanding of Le Chateliers principle understand that a catalyst will increase both the forward and backward rate by the same amount and therefore will have no effect on equilibrium. C8.9 Altering Condition s Higher Only Aiming for Grade 6 LOs:  Explain how changing conditions for a system at dynamic equilibrium affects the rate of the forward and reverse reactions.  Predict the effect on yield of changing temperature, concentration, or pressure I a given equilibrium system. Can we manipulate reversible reactions so they only go in one direction? How can we make fertiliser if the reaction is reversible? Lesson Overview Starters Equilibrium equation (5 minutes) Ask students to write an equilibrium equation for dinitrogen tetroxide turning into nitrogen dioxide. Make sure students use the equilibrium arrow ⇋. Le Chatelier’s tweet (10 minutes) Using the student book and notes from the previous lesson, students summarise Le Chatelier’s Principle in a tweet (no more than 140 characters). Mains Observing equilibrium (20 minutes) Explain to students that at room temperature and pressure, nitrogen dioxide is a brown gas and dinitrogen tetroxide is a colourless (pale yellow) gas. Ask students to write the equation for the reaction. Encourage students to predict the effect on the position of equilibrium when the temperature is lowered or increased. Demonstrate the effect and ask students to explain the observation of the colour change. Ask students to predict the effect of changing pressure, demonstrate this, and again ask students to explain their observations. The Haber Process (20 minutes) Explain to students that ammonia is an important feedstock chemical for making fertilisers. It can be made by a reversible reaction between hydrogen and nitrogen gas. Ask students to write an equation for this reversible reaction. Then explain that the forward reaction is exothermic. Ask students to determine the energy change for the backward reaction. Label the high and low pressure sides of the equation. If necessary, briefly remind students of Le Chatelier’s Principle. Then ask students to work in small groups to suggest the effect on the yield of ammonia of changing the temperature and the pressure. QnA between teachers and students Written responses to questions Class discussion Equations produced for all reactions mentioned during the lesson So3 C3 Sp2 Sp9 C5 So7 Aiming for Grade 8 LOs:  Explain why changing pressure has no effect on some systems.  Justify, in detail, the compromise conditions chosen in given industrial processes.