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Description
Flashcards by Natalia Cliff, updated more than 1 year ago
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Created by Natalia Cliff
almost 7 years ago
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| Question | Answer |
| What is cracking? | Cracking is when hydrocarbons are split into smaller, more useful molecules |
| What is the process for cracking? | -heat to vaporise hydrocarbons -pass vapours over a hot catalyst (usually steam) -This allows thermal decomposition to occur |
| What are the products of cracking? | -alkanes (saturated) -alkenes (unsaturated) |
| What is the general formula and structure of alkenes? |
CnC2n
Image:
Propene (image/gif)
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| How do you test if a hydrocarbon is an alkene? | The hydrocarbon is put into bromine water. If it is an alkene it will turn the orange bromine water colourless |
| What are the products of cracking useful for? | -smaller alkanes useful as fuels -alkenes can be used as polymers |
| How are polymers made? | Many smaller molecules (monomers) are joined to make a very large molecule (polymer). e.g. ethene can be made into poly(ethene) (the brackets are important) |
| How do you draw the structure of a polymer? |
Image:
Polyethene (image/jpeg)
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| What are polymers used for? | -packaging material -waterproof coating -fabrics -dental polymers -wound dressings -Hydrogels -smart materials (e.g. shape memory polymers) |
| What is an issue with polymers? | Most polymers aren't biodegradable, so they are not broken down by microbes. This can lead to waste problems with landfill sites an litter |
| How is this issue being dealt with? | Plastic bags are being made with polymers and cornstarch so that they break down more easily |
| How can ethanol be produced? | -hydration of ethene with steam and a catalyst (high temp) -fermentation of sugar with yeast sugar -> carbon dioxide + ethanol |
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