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Pearson GCSE Chemistry

QuestionAnswer
What is the optimum temperature for fermentation? Around 38°C
Why is fermentation done in the absence of air? Because the presence of air can cause extra reactions to occur.
What is the chemical formula for Ethanol? C2H5OH
What are sugars and which food group do they belong to? Sugars are small, soluble substances that belong to a group called carbohydrates
Give the word equation for fermentation Glucose → ethanol + carbon dioxide
Which plants are used to produce the following drinks? Beer Wine Whisky Vodka? 1) Beer - barley seeds 2) Wine – grapes 3) Whisky – barley seeds 4) Vodka – Wheat seeds
Why does fermentation need to take place in the absence of air? The presence of air can cause extra unwanted reactions to occur
What does the air lock in a fermentation jar do? The air lock allows the carbon dioxide to escape while keeping the air out
During fermentation, why must the temperature and pH be carefully controlled? To help the enzymes work at their best.
What concentration of alcohol does the fermentation of alcohol produce? What happens to yeast in higher alcohol concentrations? 15% - anything higher will kill the yeast cells
What process can be used to produce more concentrated solutions of ethanol? Fractional distillation
What is the boiling point of ethanol? 78°C
What is a homologous series? A family of compounds that have the same general formula and similar properties, but have different numbers of carbon atoms
Give the names and molecular formulas of the first 4 alcohols 1) Methanol – CH3OH 2) Ethanol – C2H5OH 3) Propanol – C3H7OH 4) Butanol – C4H9OH
What is the functional group of alcohols -OH
What is the functional group of carboxylic acids? -COOH
What is the general formula of alcohols? CnH2n+1OH
What is the general formula of carboxylic acids? CnH2n+1COOH
Give the name of two products that are form in the complete combustion of all alcohols Carbon dioxide and water
What is an oxidising agent? A substance that causes another substance to be oxidised in an oxidation reaction
How are carboxylic acid formed? By the gentle oxidation of alcohols using oxidising agents
Name the products formed when carboxylic acids react with bases Salt + water
Name the products formed when carboxylic acids react with carbonates Salt + water + Hydrogen
What functional group do all alcohols have? OH
Name and draw the first four alcohols Methanol, ethanol, propanol, butanol (ethanol pictured)
What happens when an alcohol reacts with sodium? It forms a sodium salt (e.g. sodium ethoxide from ethanol) and releases hydrogen gas.
What are the products of a combustion reaction involving an alcohol and oxygen? Carbon dioxide and water
Write a symbol equation for the reaction of methanol/ethanol/propanol/butanol with oxygen E.g. CH₃CH₂OH + 5O₂ → 2CO₂ + 3H₂O
Do alcohols dissolve in water? Yes, they form neutral solutions
How do alcohols react with oxidizing agents? They turn into carboxylic acids
What are the main uses of alcohols? Solvents, ethanol used as drinking alcohol and a biofuel
What is fermentation? The process of turning glucose (a natural sugar) into ethanol
What is required for natural fermentation? Yeast
What functional groups do all carboxylic acids have? COOH
Name and draw the first four carboxylic acids Methanoic acid, ethanoic acid, propanoic acid, butanoic acid (image is ethanoic acid)
Why are carboxylic acids weak acids? Not all their molecules ionise when in water
What is made when ethanol is oxidised? Ethanoic acid
How do you compare the energy released by alcohols when they are combusted. Burn the alcohol, use the energy to heat water. Measure the temperature change of the water. Calculate the temperature change caused per gram of alcohol burnt.
What is made when ethanol is dehydrated? An alkene
How can ethanol be concentrated? Distillation
Why do alcohols have the same type of reactions? They are part of the same homologous.
What group do molecules with an -OH belong to? alcohols
What group do molecules with an -COOH belong to? carboxylic acid
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