GCSE: OCR gateway: C2: manufacturing chemicals + acids and bases
- Created by: 09tvzutphen
- Created on: 07-04-14 21:36
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- C2
- Manufacturing Chemicals; Making Ammonia
- The Harber Process
- World food production depends on nitrogen fertilisers made from ammonia
- Nitrogen + Hydrogen Ammonia
- N2 + 3H2 2NH3
- Optimum conditions
- Use a catalyst made of iron
- Increases reaction rate; collisions per second but not the percentage yield
- Temperature around 450*c
- Increases reaction rate
- High temperature breaks down ammonia reducing percentage yield
- High pressure; 200 atmospheres
- Increases percentage yield of ammonia
- Recycle unreacted nitrogen and hydrogen
- Use a catalyst made of iron
- What affects the cost of chemical manufacture?
- Costs increase when pressure (plant costs) and temperature (energy costs) are raised
- Costs decrease
- A catalyst is used
- Unreacted materials are recycled
- Automation is used;less wage bills
- Economic considerations to determine the conditions
- Both reaction rate and percentage yield are high enough to give sufficient daily yield of product
- Low percentage yield acceptable if reactionis repeatable and materials can be recycled
- Optimum conditions give lowest cost rather than the fastest rate or highest yields
- The Harber Process
- Acids and Bases
- Alkalis and Neutralisation
- Metal oxides and hydroxids are bases
- Bases soluable in water are alkalis
- Neutralisation Acid + base = salt + water
- Neutralisation leaves no free H+ ions
- H+ + OH- H2O
- Some indicators show a sudden colour change to one pH value
- Universal indicator shows a gradual range of colour changes as it contains a mixture of different indicators
- In solutions all acids contain H+ ions
- The higher the concentration of H+ ions the lower the pH
- Alkalis contain OH- ions
- Salts
- Acids react with bases and metal carbonates to form salts
- Neutralisation Acid + base = salt + water
- Neutralisation leaves no free H+ ions
- H+ + OH- H2O
- Acid + metal carbonate = salt + water + carbon dioxide
- Neutralisation Acid + base = salt + water
- 2nd part of the name tells you what acid it has been made from
- Acids react with bases and metal carbonates to form salts
- Alkalis and Neutralisation
- Manufacturing Chemicals; Making Ammonia
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