C4 Chemical Calulations Flashcards
How to find ‘Concentration’?
Concentration = Moles/Volume
mol/dm^3
What is titration?
An experiment which uses a neutralisation reaction to find out an unknown concentration
What are concordant results?
Results with a difference of 0.1
What colour is pheolphthlane in an acid?
Colourless
What colour is pheolphthlane in an alkali?
Pink
How to do the titration experiment?
- Prepare and fill a burette with acid.
- Record the initial volume of the acid in a suitable table.
- Using a clean, dry pipette, transfer 25.0 cm3 of alkali into a conical flask.
- Add four drops of a suitable indicator to the alkali.
- Add acid to the alkali, swirling the conical flask to mix.
- When the indicator starts to change colour, add the acid dropwise (still swirling) until the end-point is reached.
- Record the final volume of acid added.
- Repeat until two concordant results are obtained.
How to find moles in a gas volume calculation?
Moles = volume/24(dm^3)
What is percentage yield?
Percentage yield = (Actual yield / Theoretical yield) x 100
Why is percentage yield always less than 100%?
1) Some products are lost in the process (gasses escaping)
2) Incomplete reaction
3) Some reactants may contain impurities
4) Some reactions are reversable
What is atom economy?
Atom economy = (Mr of desired product/Mr of all prodcuts) x 100
How much atom economy can a reaction with one product produce?
100%
What are the enviromental adavntages of high atom economy?
- Less waste
- More raw materials to conserve
What are the economical adavantages of high atom economy?
- Less cost for wate disposal
- Less cost for raw materials
What is the volume of 1 mole of gas?
24dm^3
or
24000cm^3
How can we use balanced equations to work out reacting masses?
It tell you the mole ratio
E,g.
H2 + Cl2 ——> 2HCl
1mole of hyrogen and 1mole of chlorine make 2moles of hydrogen chloride
