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steve_ell

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i have a prac test on tuesday... my last assesment and im having trouble with equilibrium and titration. i know the theory and what to do with titration... i was just wondering what sor of questions they ask........... ie the mole ones.

with equilibrium im realy having trouble with equasions and how to write them......... n e advice would be really appreciated.

thanx
 

~*HSC 4 life*~

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in titration they usually ask you to find the molarity of the analyte, using stoichiometry. Usually you are given the volume and concentration of the titrant, use the equation n= C x V to find the number of moles, use the mole ratio from the equation you the titration reaction to calculate no of moles of solution you wish to find molarity, then use C= N/V it's as simple as pie :)

In titration they may also describe the strength of the acids/bases they are using and ask you to choose a suitable indicator for the experiement

eg they might tell you that a strong base is beign titrated against a weak acid, so you might say phenolpthalein is a good choice as it can change colour between pH 8-10ish <-- remember a strong base and a weak acid will give a slightly basic solution

For equilibrium, you just have to write them as normal eq's with the double ended arrow...hmm id on't know if thats the help you needed...just make sure you practice a few in writing...in exams theyw ill usually get you to write the equil reactions you have seen before and should know eg carbon dioxide dissolving in water, auto dissociation of water, buffer systems such as hydrogen carbonate/hydrogen phosphate ions and the haber process (synthesis of ammonia)

More importantly, make sure you udnerstand equil reactions, exams tend to focus on how equil works rather than gettign you to write one down as they are usually given to you...know what happens to the position of equil when heat is increased, pressure increased, vol increased etc
 

CM_Tutor

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Please don't use the dilution formula C<sub>1</sub>V<sub>1</sub> = C<sub>2</sub>V<sub>2</sub> for titration calculations.
 

xiao1985

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CM_Tutor said:
Please don't use the dilution formula C<sub>1</sub>V<sub>1</sub> = C<sub>2</sub>V<sub>2</sub> for titration calculations.
lolz!!! couldn't agree more... try to use moles of reactants/products... tis more legit =)
 

CM_Tutor

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xiao1985 said:
lolz!!! couldn't agree more... try to use moles of reactants/products... tis more legit =)
We actually deduct marks from Uni students who use this approach, because it isn't really 'legit'.
 

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