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CHEMISTY paper 2 - Coggle Diagram
CHEMISTY paper 2
Fractional distillation
- crude oil (mixture of hydrocarbons) mostly alkanes is heated most alkanes evaporate
- column is hot at top and cool at the bottom
- gaseous alkanes condense at there boiling point
WHY? alkanes have different boiling points , bigger alkanes have stronger intermolecular forces which require more energy to break
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dynamic equilibrium
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Le Chatelier’s Principle
1) adding or removing reactants or products -- can see colour changes by the equilibrium is being disturbed- shifting to the right or left depending on starting colour and how much you add
2) changing pressure -- increased pressure shifts the equilibrium to where the is the fewest moles of gas
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Harbor process
making ammonia
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optimum conditions- pressure 200atm- need high pressure to increase yield but not too high for expense and safety reasons
Need low temperature to increase yield of NH3 , but high temperature to increase rate of reaction.
Fe catalyst increases rate, allowing a lower temperature to be used (saves money & leads to increase in yield of NH3
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REACTIONS
Flame test
- Dip wire in hydrochloric acid, then put into flame;
- Repeat until wire is clean (no flame colour)*;
- Dip wire in hydrochloric acid, then into the sample;
- Put wire in flame and observe colour of flame.
- Must be done, otherwise a colour from an impurity could mask the flame colour of the sample.
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RATES OF REACTION
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Collision theory
concentration- more crowded particles ,more frequent collisions
surface area- more exposed particles, more frequent collisions, higher probability of successful conditions
increasing temperature- faster particles= more frequent collisions, more energetic conditions
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