C7.5 chemistry full

full c7.5 ocr 

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  • Created by: callum
  • Created on: 26-05-11 13:03

Chemical industry.

The chemical industry make bulk chemicals such as:

Sukphuric acid, ammonia, sodium hydroxide, phosoric acid.

The chemical industry also make fine chemicals such as:

Medicinal drugs, chemicals for fragrences, food additives.

The industry employs chemists for research and development to discover:

- new products to meet a new need.

- new ways to make a product more cheaply or sustainibly.

Government health and safety regulations control chemical processes and the transoptation and storage of the chemicals. The regualtions protect people such as workers.

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Producing useful chemical stages.

1. convert raw materials into feedstocks

2. Convert feedstocks into products by synthesis. It happens in a reactor. Feedstocks may be fed into a reactor at high temperature or high pressure. The reactor may contain a catalyst.

3. The chemical plant separates products, by-products and waste which leave the reactor. Unreacted feedstock returns to the reactor. 

4. Analysing the products to check purity.

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Green chemisty.

Green chemistry aims to make processes as safe and sustainable as possible:

- using renewable feedstocks: e.g make polyester from corn starch rather than crude oil.

- Making the process efficient: measured as atom economy      atom economy = mass of atoms in product / mass of atoms in reactant X 100%

- reducing waste: processes with higher atom economy, recyling, uses for by-products.

- Make processes more energy efficient: insulating pipes, use energy from exothermic reactions.

- lower energy demand of a process: use biocatalysts so it can run at low temp.

- cutting pollution from waste: remove harmful chemicals before sending them to landfill sites.

- Avoid hazardous chemicals: replace toxic feedstocks with chemicals that do not harm human health or the environment.

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Making Ethanol by Fermentation.

There are 3 ways to produce Ethanol. One way is by Fermentation.

Fermentation converts sugars into Ethanol. Carbon dioxide is the by-product.

e.g :     glucose sugar--------> Ethanol + carbon dioxide

Enzymes in yeast catalyse fermentation

The optimum temperature is 25-37 degrees Celsius.

- Above this temperature the enzymes denature.

- Below the reaction is too slow

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Making ethanol from Ethane.

Feedstock for this is Ethane and Steam.

Ethane is obtained from crude oil.

- The process uses a phosphoric acid catalyst.

- The best temp. is 300 and a pressure of 60 atmospheres.

- Ethane and steam are sent through the reactor many times.

- Side reactions make dangerous by-products.

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Making Ethanol from waste Biomass

Waste biomass is being developed to produce Ethanol. these are the stages:

1.  Pretreatment: mashing the biomass into small pieces.

2.  Hydrolysis: Using genetically modified Enzymes to convert celluse into sugars.

3.  Separating: sugars from other products.

4.  Distilling: Ethanol to make a more concentrated solution.

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