Analysis and Synthesis
This is about analysis of substances, the Haber Process, titrations, and other chemistry things.
- Created by: Lizzi
- Created on: 28-04-13 17:55
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- Analysis and Synthesis
- Tests for positive ions
- Most group 1 & 2 metals can be identified by flame tests
- Litium (Li+) = Crimson/ red
- Sodium (Na+) = yellow
- Potassium (K+) = lilac
- Calcium (Ca2+) = red
- Barium (Ba2+) = green
- Sodium hydroxide solution can be used to identify different metal ions, depending on the precipitate it produces
- Aluminium, Calcium, and Magnesium = white
- Copper (II) Hydroxide = blue
- Iron (II) Hydroxide = green
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- Most group 1 & 2 metals can be identified by flame tests
- Tests for negative ions
- Carbonates are identified by adding dilute acid. This produces CO2, which turns limewater cloudy.
- We identify halides by adding nitric acid; it produces silver halide.
- Chloride = white
- Bromide = cream
- Iodide = pale yellow
- We identify sulfates by adding hydrochloric acid and barium solution, which produces barium sulfate.
- Titrations
- A titration is used to measure how much acid and alkali react together completely
- The point at which an acid-base reaction is complete is called the End Point.
- An indicator is used to show when the end point.
- Concentration is measured in g/dmcubed or mol/dmcubed
- Conc. can be calculated by the mass of a solute in a known solution volume (and vice versa)
- If the conc. of one solution is known, the results of the titration can be used to calculate the conc. of the other solution.
- Chemical analysis
- Scientists working in environmental monitoring, medecine, and forensics need to analyse substances.
- The results are usually matched against existing data to identify substances/ suspects.
- Chemical equilibrium
- In a reversible reaction, the products can re-react to form the original reactants.
- In a closed system, equilibrium is achieved when the rates of the forward and reverse reaction are equal.
- Changing the conditions can alter the amount of products and reactant.
- Altering Conditions
- Changing the pressure can affect a reversible reactions involving gases at equilibrium
- Increasing favours the side with the smaller number of gas molecules formed.
- Decreasing favours the side with less gas molecules.
- Changing the temp. will vary the amount of products formed at equilibrium.
- Increasing temp. favours endothermic reaction
- Decreasing temp. favours endothermic reaction.
- Changing the pressure can affect a reversible reactions involving gases at equilibrium
- Haber Process
- Ammonia is an important chemical that makes things like fertilisers
- It's made from nitrogen and hydrogen.
- Haber Process is done using conditions chosen to give a reasonable yield of ammonia as quickly as possible
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- The economics of the Haber Process
- It uses pressure of about 200 atmospheres,to increase ammonia production.
- Although higher pressure creates more ammonia, less is used as more would be too expensive.
- A temperature of 450 degrees C is used.
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- Tests for positive ions
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