2805214
Description
Flashcards by Tom Mitchell, updated more than 1 year ago
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Created by Tom Mitchell
over 9 years ago
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| Question | Answer |
| What is the purpose of putting additives in food? | Allows the food to last longer, taste better or look better |
| What do food colours do? | Make food look more appealing |
| What do flavour enhancers do? | Bring out the taste and smell of the food without adding their own |
| What do antioxidants do? | Help to preserve food |
| What do emulsifiers do? | Helps two liquids from separating out |
| What are the 4 advantages of cooking foods? | Some foods have a better taste or texture when cooked Some foods are easier to digest when cooked Cooking kills off harmful microbes that cause disease Some foods are poisonous unless they are cooked |
| Is cooking a reversible or irreversible change? | Irreversible |
| What happens to protein molecules when they are cooked? | They change shape as the chemical bonds between the molecules are broken down with the energy from cooking, they denature. This gives the food a more edible texture. |
| What happens to potatoes when they are cooked? | The cell wall, made of cellulose, ruptures. Starch grains swell up and spread out. These changes allow potatoes to have a more edible texture and make them easier to digest. |
| What process does baking powder undergo when it is heated? | Thermal Decomposition |
| What is the word equation for the decomposition of baking powder? | |
| What is the balanced symbol equation for the decomposition of baking powder? | |
| How can carbon dioxide be detected? | Using limewater The limewater will turn cloudy if carbon dioxide is present |
| How are esters made? | Esterification |
| What is the word equation for esterification? | Acid + Alcohol --> Ester + Water |
| Why are esters used in perfumes? | They usually smell nice |
| What is volatility? | How easily a liquid evaporates |
| Why must perfumes be volatile? | So that the liquid can evaporate and be smelt |
| Why are perfumes insoluble in water? | So that the smell does not get washed off easily |
| Why has the testing of cosmetics been banned by the EU? | Some people have ethical concerns and believe its wrong to harm animals to check the safety of products |
| Why will water not dissolve nail varnish? | The molecular bonds between the water molecules are stronger than the molecular bonds between the water molecules and the nail varnish molecules. The separate substances have stronger bonds between themselves than with each other |
| Why do some people believe that testing cosmetics on animals is justified? | It prevents humans from harm |
| What is a colloid? | A colloid consists of tiny particles dispersed in another substance |
| Why will the components of a colloid not separate? | The particles are very small so they do not settle at the bottom |
| What happens to the paint as the solvent evaporates? | It dries This just leaves the pigment and binding medium as a thin film |
| How do oil paints dry? (Two Stages) | First the solvent evaporates Then the oil is oxidised by the oxygen in the air |
| What are the 3 components in a paint? | Solvent Binding Medium Pigment |
| How are thermochromic pigments suited to their uses? | They can easily show if something is too hot |
| How do thermochromic pigments change acrylic paint colours? | Mixing an acrylic paint with a thermochromic paint allows colours changes when the paint is heated. The thermochromic paint will become transparent, leaving only the other colours in the mixture and therefore changing the colour |
| How do phosphorescent pigments glow in the dark? | The molecules in the pigment absorb natural or artificial light and store the energy. The energy is slowly released as light energy |
| Why are phosphorescent pigments now used? | Radioactive paints were used but these gave off harmful atomic radiation. Phosphorescent pigments are a much safer alternative |
| What bonds do alkanes have? | Single covalent bonds |
| What bonds do alkenes have? | At least one double covalent bond |
| What does 'unsaturated molecule' mean? | The molecule has at least one double covalent bond |
| What is a hydrocarbon? | A molecule that only contains hydrogen and carbon atoms |
| What is the process called when many monomers join together? What is the product called that this process produces? | Polymerisation Polymer |
| How can you test for alkenes? | Bromine Water If the solution decolourises then alkenes are present, a di-bromo compound is formed |
| What conditions are needed for polymerisation to occur? | A catalyst and high pressure |
| What type of bonds are in polymers? | Covalent |
| What are the favourable properties of Nylon? | Lightweight Tough |
| Why is GORE-TEX material favourable over Nylon? | It has the same properties of Nylon except it is breathable - water vapour can escape (so no condensation) |
| How is GORE-TEX breathable yet waterproof? | GORE-TEX has tiny holes in it that allow small molecules, like water vapour, through but block bigger molecules, like water droplets |
| Why are chemists researching bio-degradable polymers? | So that plastic waste is able to be broken down and not sit in landfill sites for years |
| Why is it difficult to get rid of plastics? (3) | Landfills fill up quickly Plastics are not bio-degradable Burning plastics release toxic chemicals like sulfur dioxide, hydrogen chloride and hydrogen cyanide |
| What would the properties be of a plastic with weak intermolecular forces? | Low melting point Stretchy |
| What are some uses of crude oil? (3) | Provides energy for generating electricity & heating homes Provides fuel for modern transport Provides raw materials need to produce plastics |
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