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28 Cards in this Set
- Front
- Back
1. What is a mixture? |
• A mixture is something made up of 2 or more substances that are not chemically bonded together and can be separated. |
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2. Name three separation techniques |
• Chromatography •Filtration •Evaporation •Distillation |
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3. What separation technique would you use to separate 2 substances that have different boiling points? |
• Distillation |
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4. What is crude oil? |
• Crude oil is a mixture of compounds known as hydrocarbons. |
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5. Alkanes are found in crude oil. What are alkanes? |
• Saturated hydrocarbons |
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6. What two elements are present in hydrocarbons? |
• Hydrogen and Carbon |
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7. What is the general formula for alkanes? |
• CnH2n+2 |
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8. When drawing displayed formulas what do the lines between the atoms represent? |
• The lines between atoms represent bonds. |
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9. How are the many hydrocarbons in crude oil separated into fractions by fractional distillation? |
• Crude oil is heated vaporised and fed in at the bottom of the fractionating column • The column is hotter at the bottom and cooler at the top • The fractions are separated by their different boiling points • Hydrocarbons that have lower boiling points are collected near the top of the fractionating column and hydrocarbons with higher boiling points are collected near the bottom of the fractionating column • The gases condense when they reach the temperature of their boiling points • The different fractions are collected as liquids at different levels of the fractionating column. |
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10. What is meant by viscosity? |
• Viscosity is how easily a liquid can flow. |
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11. How does the size of a molecule affect the viscosity of a hydrocarbon? |
• Shorter chained hydrocarbons have a low viscosity (runny) and longer chained hydrocarbons have a high viscosity (thick). |
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12. What is meant by volatility? |
• Volatility is the tendency for a liquid to turn into a gas |
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13. How does the size of a molecule affect the volatility of a hydrocarbon? |
• Shorter chained hydrocarbons are very volatile and longer chained hydrocarbons are not volatile. |
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14. What is meant by flammability? |
• Flammability is how easily something can burn |
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15. How does the size of a molecule affect the flammability of a hydrocarbon? |
• Shorter chained hydrocarbons have high flammability therefore burn easily • Longer chained hydrocarbons have a low flammability and therefore do not burn very easily. |
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16. What length hydrocarbons are the most useful as fuels and what do they release when they burn? |
• Short chained hydrocarbons are very useful as fuels and release energy when burned. |
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17. What does combustion mean? |
• Combustion is the process of burning something. |
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18. What is complete combustion? |
• When something burns in plenty of oxygen. |
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19. What is incomplete combustion? |
• When something burns in insufficient oxygen therefore the fuel cannot react completely. |
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20. What is the word equation for the complete combustion of a hydrocarbon and the incomplete combustion of propane? |
• hydrocarbon + oxygen → carbon dioxide + water (complete) • hydrocarbon + oxygen → carbon monoxide + carbon + water (incomplete) |
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21. What is the balanced symbol equation for the complete combustion of propane? |
• C3H8 + 5O2 → 3CO2 +4H2O |
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22. What is the balanced symbol equation for the incomplete combustion of ethane? |
• C2H6 +2 2O → CO + C + 3H2O |
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23. Apart from carbon dioxide water and carbon monoxide; what other products can be made from combustion? |
• Sulphur dioxide • Oxides of nitrogen • solid particles called particulates. |
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24. What environmental problems are caused by sulphur dioxide/nitrogen oxides and particulates? |
• Sulphur can react with oxygen in the air fuels are burned forming sulphur dioxide gas. Sulphur dioxide is acidic and can cause acid rain • Nitrogen oxides are formed in a car engine and are made when nitrogen and oxygen react together at a high temperature. They can trigger people’s asthma and also cause acid rain • Particulates travel into the upper atmosphere reflecting sunlight back into space causing global dimming |
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25. How can the problems caused by impurities be reduced? |
• Removing sulphur from the fuel before combustion and removing the waste gases produced after combustion. |
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26. What is a biofuel? |
• A fuel that is made from plant or animal products. |
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27. What are the benefits and draw backs of using ethanol as a fuel? |
• Benefits: Ethanol is made by fermenting sugar so is therefore renewable and saves our crude oil supplies.Sugar cane crops will absorb carbon dioxide during photosynthesis. • Drawbacks: Large amount of land is required to grow crops. |
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28. What are the benefits and draw backs of using hydrogen as a fuel? |
• Benefits: Hydrogen burns with a clean flame as there is no carbon in the fuel• No pollutants made when hydrogen burns.• Water is a huge natural source of hydrogen (obtained by electrolysis) • Drawbacks: When hydrogen is mixed with air and ignited is it very explosive.• Hydrogen is a gas and takes up larger volumes than liquid so there are issues with storage. |