Chemistry C3
- Created by: Bookworm1504
- Created on: 20-04-20 14:20
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- Chemistry C3
- Relative Formula Mass
- The Mr is the relative atomic masses of all the atoms in a compound
- Percentage mass = Ar x number of atoms /Mr of compound
- The Mole
- 6.02 x 10p23
- 1 mole of any given substance will have a mass equal to the Mr of that substance
- E.g. Ar of Carbon is 12, so 1 mole of carbon weighs 12g
- No of moles = mass / Mr
- Conservation of Mass
- No atoms are destroyed or created during a reaction
- This is why equations need to be balanced
- If mass changes in a reaction:
- If mass increases, it's likely that one of the reactants is a gas
- If mass decreases, it's likely that one of the products is a gas.
- No atoms are destroyed or created during a reaction
- Limiting reactants
- Reactions stop when all of one reactant (the limiting reactant) has been used up.
- All other reactants are in excess
- Reactions stop when all of one reactant (the limiting reactant) has been used up.
- Relative Formula Mass
- Limiting reactants
- Reactions stop when all of one reactant (the limiting reactant) has been used up.
- All other reactants are in excess
- Reactions stop when all of one reactant (the limiting reactant) has been used up.
- Atom Economy
- Atom economy = Mr of desired product / Mr of all reactants
- A higher atom economy is better for profits and the environment
- It is more beneficial to find a reaction that gives useful bi-products rather than ones which will be wasted.
- Percentage Yield
- percentage = mass of product made / maximum theoretical mass of product
- Always less than 100%
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