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Chemistry titration urgent

I have my Unit 3 EMPA for chemistry soon.

My question is will the mass of a substance affect the titration value?
Reply 1
Avatar for ccalby
ccalby
Hello,

Your question confused me a bit.

I assume you mean if you have more mass in the solution being titrated; does that affect the titration value?
The answer to that is yes. The reason is more mass means more moles (Mass = Moles x Mr).

More moles in your solution means it will take more moles of X to titrate your sample. This means the reading on your Burette will be higher.

Thanks,

P.S - I have my written ISA tomorrow. Just revise :wink:
Reply 2
Avatar for Rickstahhh
Rickstahhh
OP
6
Original post by ccalby
Hello,

Your question confused me a bit.

I assume you mean if you have more mass in the solution being titrated; does that affect the titration value?
The answer to that is yes. The reason is more mass means more moles (Mass = Moles x Mr).

More moles in your solution means it will take more moles of X to titrate your sample. This means the reading on your Burette will be higher.

Thanks,

P.S - I have my written ISA tomorrow. Just revise :wink:


I am a little confused, because on previous EMPA markschemes which involve titrations it states that you are marked for accuracy out of 4 marks.

4 Marks for within 1% of teachers mean titre
3 Marks for within 1.5% of teachers mean titres
etc

So, this is odd, as everyone would have slightly different masses as we have to weigh them out. Therefore our titres are likely to differ due to mass differences.
So how can they mark it against the teachers titre, as his mass would be different?
Reply 3
Avatar for Lolzland
Lolzland
Original post by Rickstahhh
I am a little confused, because on previous EMPA markschemes which involve titrations it states that you are marked for accuracy out of 4 marks.

4 Marks for within 1% of teachers mean titre
3 Marks for within 1.5% of teachers mean titres
etc

So, this is odd, as everyone would have slightly different masses as we have to weigh them out. Therefore our titres are likely to differ due to mass differences.
So how can they mark it against the teachers titre, as his mass would be different?


I looked up on that EMPA - you didn't have to make a standard solution. They provided you with a reagent of a specific concentration. This would be the same for everyone (inc. the teachers) - however I understand there are differences but that's why AQA give you ±1% leeway.
Reply 4
Avatar for Rickstahhh
Rickstahhh
OP
6
Original post by Lolzland
I looked up on that EMPA - you didn't have to make a standard solution. They provided you with a reagent of a specific concentration. This would be the same for everyone (inc. the teachers) - however I understand there are differences but that's why AQA give you ±1% leeway.


Thanks,

I done the titration today, the results in the class differed greatly.

[Mod edit: Removed specifics]

This is a huge variation and would not fall within the leeway.
(edited 10 years ago)

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