Revision Lesson part one 30/11/2018 C1 – Carbon Chemistry Revision Lesson part one

30/11/2018 Revision Lessons Does not contain all of the content for C1 – use checklists ..\C1 Carbon Chemistry\C1 Summary & Checklists\C1 Checklist Foundation.doc ..\C1 Carbon Chemistry\C1 Summary & Checklists\C1 Checklist Higher.doc

The Chemistry of Cooking 30/11/2018 The process of cooking food causes some chemicals to turn into others (i.e. a chemical change) and these are irreversible. For example, consider a protein molecule: “Denatured”

Exam Questions Standard Demand 30/11/2018 Standard Demand 1.) Some foods need to be cooked. Explain why? (2 marks) 2.) Cooking food is an example of a chemical change. Finish the sentences to explain why. Choose the best words from the list. Energy irreversible reactant reversible substance The change is___________. An ___________ change takes place in the food. A new ________ is made. (3 marks) 3.) What happens to protein molecules when they are cooked? (1 mark)

The Chemistry of Cooking 30/11/2018 Now consider a potato cell: Cooking a potato causes the cell wall to break and release starch grains – making it softer/easier to digest

Sodium hydrogen carbonate sodium carbonate + water + carbon dioxide Baking Powder 30/11/2018 Baking powder is used to make bread rise: This is a thermal decomposition reaction Sodium hydrogen carbonate sodium carbonate + water + carbon dioxide 2 NaHCO3(s) Na2CO3(s) + H20(g) + CO2(g) Gas Testing for carbon dioxide - makes cakes/bread rise: Limewater Limewater turns milky/cloudy

Exam Questions Standard Demand 30/11/2018 Standard Demand 1.) Baking powder is a chemical called sodium hydrogencarbonate. When it is heated it decomposes to give sodium carbonate, carbon dioxide and water. a.) Write down the word equation for this reaction. (2 marks) b.) Write down the reactants of the reaction. (1 mark) c.) Write down the products of the reaction. (1 mark) 2.) The chemical test for carbon dioxide is to pass it through limewater. It will turn the limewater from _______ to _______. (2 marks)

Exam Questions High Demand 30/11/2018 High Demand 1.) The formula for sodium hydrogencarbonate is NaHCO3. Write down the balanced symbol equation for this reaction. (3 marks)

30/11/2018 Food Additives

Artificial Additives Additive Why Flavour enhancers 30/11/2018 Why do we use additives? Some examples: Additive Why Flavour enhancers Bring out taste and smell of food Food colouring makes food look more appetising Antioxidants Stops reaction with oxygen, preserves food Emulsifiers Help oil and water mix in foods like salad cream and ice cream

Emulsions What’s an emulsion? 30/11/2018 What’s an emulsion? It’s a mixture of oil and water, like in salad dressing… Butterfat Paint is an emulsion. Other examples: Watery liquid Milk Cream Butter

Emulsifiers - the details 30/11/2018 Water Oil - + Emulsifier - - - - + -

Foundation – 6 mark question 30/11/2018 The quality of written communication will be assessed in your answer to this question. Explain why cooking a meat is described as a chemical change.

30/11/2018 Level 3 Answer correctly applies knowledge of how meat is a protein, description of how cooking is a chemical change because it involves an energy change that is irreversible. Understanding of how proteins change shape-denatures. All information in answer is relevant, clear, organised and presented in a structured and coherent format. Specialist terms are used appropriately. Few, if any, errors in grammar, punctuation and spelling. (5–6 marks) Level 2 Answer applies knowledge of how cooking meat is a chemical change due to heating the food, causing an energy change and irreversible reaction. Specialist terms are used for the most part appropriately. There are occasional errors in grammar, punctuation and spelling. (3–4 marks) Level 1 An incomplete answer, states cooking is a chemical change because the reaction is irreversible. Answer may be simplistic. There may be limited use of specialist terms. Errors of grammar, punctuation and spelling prevent communication of the science. (1–2 marks) Level 0 Insufficient or irrelevant science. Answer not worthy of credit. (0 marks)

Higher - 6 mark question 30/11/2018 The quality of written communication will be assessed in your answer to this question. Explain how even though mayonnaise is made of oil, vinegar and egg yolk, it still makes a smooth substance.

30/11/2018 Level 3 Answer correctly applies knowledge of how egg yolk has two part, one part is hydrophobic and the other part is hydrophilic , description of how these two parts allow the oil and water in mayonnaise to stay together .All information in answer is relevant, clear, organised and presented in a structured and coherent format. Specialist terms are used appropriately. Few, if any, errors in grammar, punctuation and spelling. (5–6 marks) Level 2 Answer applies knowledge of how emulsifiers work. For the most part the information is relevant and presented in a structured and coherent format. Specialist terms are used for the most part appropriately. There are occasional errors in grammar, punctuation and spelling. (3–4 marks) Level 1 An incomplete answer, states an emulsifier description. Answer may be simplistic. There may be limited use of specialist terms. Errors of grammar, punctuation and spelling prevent communication of the science. (1–2 marks) Level 0 Insufficient or irrelevant science. Answer not worthy of credit. (0 marks)

30/11/2018 Smells

Ethanol + ethanoic acid ethyl ethanoate + water Perfumes 30/11/2018 Here are some facts about perfumes. Why are these things important? Perfumes are non-toxic They are non-irritants They evaporate easily They do not dissolve in water They don’t react with water A typical perfume reaction: Ethanol + ethanoic acid ethyl ethanoate + water C2H5OH + CH3COOH C2H5OOCCH3 + H2O

Words – soluble, solute, solvent, solution, insoluble Solutions revision 30/11/2018 If a substance CAN be dissolved it is called __________ If a substance CANNOT be dissolved it is called _________ Words – soluble, solute, solvent, solution, insoluble

Higher - Making a solution 30/11/2018 A solution forms because there are: Weak forces of attraction between solute molecules Strong forces of attraction between solute and solvent molecule For example, nail varnish remover works because the nail varnish remover molecules are attracted to the nail varnish molecules with a stronger attraction than water molecules are.

Exam Questions 1. alcohol + acid --------- ester + water 30/11/2018 Standard Demand 1.) To make a perfume alcohol is mixed with an acid to make an ester. a.) Write down a word equation for this reaction. b.) Write down the name of the ester that is made from ethanoic acid and butanol. 2.) Some people object to cosmetics being tested on animals. Explain why 3.) Some people say that cosmetics should be tested on animals. Explain why. 1. alcohol + acid --------- ester + water 2. Butyl ethanoate 3. Animals may be harmed, they have no control of what happens to them 4. Feel safer if cosmetics have been tested on animals, animals reaction would closely mimic ours

Exam Questions High Demand 30/11/2018 High Demand 1.) If a liquid evaporates easily then the substance is volatile. Explain how this happens. Use ideas about forces between particles in your answer. (4 marks) 2.) Water does not dissolve nail varnish. Use ideas about the forces of attraction between molecules in your answer. (2 marks) 1. When a liquid is heated, particles will move faster, these will overcome the forces of attraction of other particles and escape, meaning the substance evaporates easily, it s volatile. 2. Molecules of nail varnish are strongly attracted to each other, and this attraction is stronger than the one between the water molecules and nail varnish

Making crude oil useful 30/11/2018 Making crude oil useful

Alkanes Alkanes are SATURATED HYDROCARBONS. What does this mean? 30/11/2018 Alkanes are SATURATED HYDROCARBONS. What does this mean? HYDROCARBONS are molecules that are made up of hydrogen and carbon atoms SATURATED means that all of these atoms are held together by single bonds, for example: C H Ethane Butane C H Alkanes are fairly unreactive (but they do burn well).

Fuels 30/11/2018 Fuels are substances that can be used to release useful amounts of energy when they burn, e.g. Wood Gas Oil Coal These fuels are called “fossil fuels” and are described as being “non-renewable”.

30/11/2018 Crude Oil

Hydrocarbons and crude oil 30/11/2018 Crude oil is a mixture of HYDROCARBONS (compounds made up of carbon and hydrogen). Some examples: Increasing length Longer chains mean… Less ability to flow Less flammable Less volatile Higher boiling point C H Ethane Butane C H

General Formulae for Alkanes 30/11/2018 Instead of circles, let’s use letters… Methane (n=1) H C Ethane (n=2) H C Propane (n=3) H C Butane (n=4) H C General formula for alkanes = CnH2n+2

Alkenes ALKANES ALKENES 30/11/2018 Alkenes are different to alkanes; they contain DOUBLE COVALENT bonds. For example: Ethane Ethene ALKANES ALKENES Butane Butene This double bond means that alkenes have the potential to join with other molecules – this make them REACTIVE.

General Formulae for Alkenes 30/11/2018 Butene (n=4) H C Propene (n=3) H C Ethene (n=2) H C General formula for alkenes = CnH2n Higher Alkenes react with Bromine water Alkene + Bromine Water = Colourless Solution + Br2 = Br H C H C

Fractional distillation 30/11/2018 Crude oil can be separated by fractional distillation. The oil is evaporated and the hydrocarbon chains of different lengths condense at different temperatures: Fractions with low boiling points condense at the top Fractions with high boiling points condense at the bottom

It’s the forces between the molecules that are broken. Remember! – It’s the forces between the molecules that are broken. The forces within the molecules (covalent bonds) are not affected by heating. covalent bond – can’t break these!

Forces between molecules 30/11/2018 Weak intermolecular force of interaction here Longer molecules = stronger intermolecular force of attraction

For example, this bond can be “cracked” to give these: Cracking 30/11/2018 Shorter chain hydrocarbons are in greater demand because they burn easier. They can be made from long chain hydrocarbons by “cracking”: Butane Ethane For example, this bond can be “cracked” to give these: Ethene

Cracking 30/11/2018 Alkene - ethene Long chain hydrocarbon - paraffin Heated catalyst Shorter alkane - octane This is a THERMAL DECOMPOSITION reaction, with clay used as a catalyst INVOLVES HEAT AND A CATALYST Cracking can be used (as well as fractional distillation) to extract petrol from crude oil. Helps supply and demand!!!!!!

Exam Questions Standard Demand 30/11/2018 Standard Demand 1.) All the oils of crude oil are hydrocarbons. What is a hydrocarbon? (2 mark) 2.) Explain how damage is done to the environment if oil tankers are damaged. (2 marks) 3.) When a large alkane is cracked it becomes a smaller alkane and an alkene. Explain why an alkene is a different type of hydrocarbon to an alkane. (1 mark) 4.) What are alkenes useful for making? (1 mark) 1. Contains hydrogen and carbon only 2. harm animals, pollutes beaches and destroys unique habitats 3. Alkenes are unsaturated (double bond) therefore more reactive 4. Polymers (plastics)

Foundation - 6 marker question 30/11/2018 The quality of written communication will be assessed in your answer to this question. 1.) A country produces 25% more than its demand of heavy oil from crude oil distillation. However, its supply of petrol from the distillation is only 68% of its need. Explain how they could solve this problem.

30/11/2018 Level 3 Answer correctly applies knowledge of how alkanes like paraffin can be broken down into more useful products such as petrol, by the process of cracking. Detailed description of cracking, including thermal decomposition reaction, high temperature and use of a catalyst. All information in answer is relevant, clear, organised and presented in a structured and coherent format. Specialist terms are used appropriately. Few, if any, errors in grammar, punctuation and spelling. (5–6 marks) Level 2 Answer applies knowledge of how cracking can be used to deal with supply and demand. For the most part the information is relevant and presented in a structured and coherent format. Specialist terms are used for the most part appropriately. There are occasional errors in grammar, punctuation and spelling. (3–4 marks) Level 1 An incomplete answer, states that cracking can be used to supply petrol. Answer may be simplistic. There may be limited use of specialist terms. Errors of grammar, punctuation and spelling prevent communication of the science. (1–2 marks) Level 0 Insufficient or irrelevant science. Answer not worthy of credit. (0 marks)

Higher - 6 marker question 30/11/2018 The quality of written communication will be assessed in your answer to this question. 1.) Explain why crude oil can be separated by fractional distillation. Use ideas about chain length, forces of attraction and boiling points in your answer. (6 marks)

30/11/2018 Level 3 Answer correctly applies knowledge of how crude oil can be separated by fractional distillation because molecules in different fractions have different length chains. Long chain molecules, such as bitumen have strong forces of attraction between molecules, meaning alot of energy is needed to break each molecule away from another, so they have high boiling points..All information in answer is relevant, clear, organised and presented in a structured and coherent format. Specialist terms are used appropriately. Few, if any, errors in grammar, punctuation and spelling. (5–6 marks) Level 2 Answer applies knowledge of how crude oil is separated by fractional distillation, including part of points but not all. For the most part the information is relevant and presented in a structured and coherent format. Specialist terms are used for the most part appropriately. There are occasional errors in grammar, punctuation and spelling. (3–4 marks) Level 1 An incomplete answer, states how fractional distillation works. Answer may be simplistic. There may be limited use of specialist terms. Errors of grammar, punctuation and spelling prevent communication of the science. (1–2 marks) Level 0 Insufficient or irrelevant science. Answer not worthy of credit. (0 marks)