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| Questão | Responda |
| How do we found out how a country has moved over hundreds of millions of years? | Magnetite cools in the direction of the Earth's magnetic field. The further the rock was from the equator, the bigger the angle of the magnetite. |
| How do fossils help geologists studying past environments? | Their characteristics help geologists work out the conditions - eg a giraffe has a long neck because trees have high leaves. |
| How do fossils help geologists date rock layers? | Fossils are often distinctive to certain time periods. |
| What is salt used for? (3 reasons) | Preserving and flavouring food, chemicals such as chlorine and applying to roads. |
| Name but don't describe the three methods for extracting salt. | Evaporating it from sea water, mining it from rock and using solution mining. |
| Describe sea salt evaporation and what it's used for. | The sun evaporates sea water from shallow pits, leaving the salt to be scraped up. It's used for food. |
| What is and what is the use of solution mining? | Water is pumped into the rock where the salt, but not impurities like clay, dissolves. The water is evaporated and the salt used in the chemical industry. |
| Describe rock mining and its uses. | Highly impure salt is mined out by machines. It's spread on roads because salty water has a lower freezing point. |
| What is the salt used in food? | Sodium chloride |
| What are the health risks associated with eating more than 6g of salt per day? | High blood pressure, leading to heart attacks and strokes. |
| Describe three properties of alkalis. | Compounds that dissolve in water to form a solution with a pH higher than 7. Can be neutralised with acid to form a salt. Solution have hydroxide ions. |
| alkaline hydroxide + acid = ? | = salt + water |
| alkaline carbonate + acid = ? | = salt + water + carbon dioxide |
| What was the Leblanc process? | A highly polluting way of making alkalis used in Victorian times. |
| Why is chlorine added to water? | It kills microorganisms that live in water, saving millions of lives. |
| What are THM's? | THM's can form when chlorine reacts with organic material such as leaves. There is an unproven theory that their consumption causes cancer. |
| What is brine? | A solution of sodium chloride (NaCl) dissolved in water (H20). Otherwise known as salty water. |
| What is electrolysis? | The process of splitting up a chemical into its elements by passing an electric current through it. |
| What happens in the electrolysis of brine? | The solution splits into sodium chloride and sodium hydroxide, with chlorine and hydrogen gas bubbling off separately. |
| What are the environmental worries over electrolysis? | It needs masses of energy, mostly from fossil fuels, and it used to use mercury which is highly toxic. |
| Why are synthetic chemicals that aren't safe still in use? | Because there is no evidence that in tiny, tiny doses they're unsafe. |
| What are POP's? | Persistent organic pollutants - they don't break down but can build up in fatty tissue. They're banned in many countries. |
| DDT is a powerful, mosquito killing pesticide. Why do some countries still use it? | The risk of malaria killing you is much higher than the risk of DDT killing you in these countries. |
| What is PVC? | A synthetic polymer that is strong, easy to use and relatively cheap. |
| What are the two raw materials for PVC, and what do they make? | Ethene and chlorine are combined to make vinyl chloride. |
| Describe vinyl chloride and how it's made into PVC. | A cancer-causing liquid made up of small molecules. Polymerisation is used to join the monomers into a polymer. |
| Describe how PVC can be recycled and why it's often difficult. | It's ground into pellets and remoulded, but often PVC is mixed with other materials, making recycling costly. |
| What is energy recovery? What are the risks? | The process of burning PVC in incinerators to produce electricity. Can very easily lead to hazardous chemicals being released. |
| What are phthalates? | The most common plasticisers for PVC. |
| Why are some people worried about plasticisers? What are the two big examples? | They can dissolve in liquids, and so get into baby's saliva from toys or into patients blood from blood bags. |
| What is DEHP? | A plasticiser banned from toys because it MIGHT cause infertility. |
| Why is DEHP still used in medical equipment? | The risk of not treating ill people is much, much higher than the risk of exposure to DEHP. There are no viable alternatives. |
| What is a life cycle assessment? | The LCA is a piece of legislation designed to protect the environment. It collects data to see how big the environmental impact will be. |
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