The Student Room Group

Removing impurities from a solution?

Hi how would you remove soluble impurities from a solution? Obviously if they were insoluble you would filter it but they're soluble.

Any guidance?:smile:
Reply 1
I am afraid this question is way to ambiguous for any reasonable answer.
You can separate the product you desire from soluble impurities in a solution through recrystallisation, if that's what you mean? Instead of removing the soluble impurities from the solution itself? :tongue:
Reply 3
Original post by Borek
I am afraid this question is way to ambiguous for any reasonable answer.
As an example... How would you separate magnesium sulphate which is soluble from a solvent... The only example I can think of is water.
Reply 4
Original post by EierVonSatan
You can separate the product you desire from soluble impurities in a solution through recrystallisation, if that's what you mean? Instead of removing the soluble impurities from the solution itself? :tongue:
What recrystallisation? Sorry I'm at AS level
Original post by Peanut247
What recrystallisation? Sorry I'm at AS level


No need to apologise :tongue:

http://simple.wikipedia.org/wiki/Recrystallisation
Reply 6
I'm not sure if they would expect me to know about that.I think the question was asking in a solution where there are soluble impurities, how would you get rid of them to leave a pure solution. E.g. Magnesium sulphate and water
Reply 7
Original post by Peanut247
I'm not sure if they would expect me to know about that.I think the question was asking in a solution where there are soluble impurities, how would you get rid of them to leave a pure solution. E.g. Magnesium sulphate and water

Im Doing Edexcels Unit 3B for AS level. And we've learnt Re-crystallisation so I assume that would be correct to use.
Reply 8
Original post by Peanut247
As an example... How would you separate magnesium sulphate which is soluble from a solvent... The only example I can think of is water.


Original post by Peanut247
I think the question was asking in a solution where there are soluble impurities, how would you get rid of them to leave a pure solution. E.g. Magnesium sulphate and water


Problem is, in your first post of these quoted you seem to be suggesting you want to separate magnesium sulfate from the solution, in the second post you seem to be suggesting you want to get rid of some other impurities and stay with as pure as possible solution of magnesium sulfate.

So, what does the initial solution contain? What do you want to separate?
Reply 9
Original post by Borek
Problem is, in your first post of these quoted you seem to be suggesting you want to separate magnesium sulfate from the solution, in the second post you seem to be suggesting you want to get rid of some other impurities and stay with as pure as possible solution of magnesium sulfate.

So, what does the initial solution contain? What do you want to separate?

I'm so bad at wording things! Sorry English isn't my first language.
Basically, the question asks how would you remove soluble impurities from a magnesium sulphate solution. So the second suggestion you made.
Would it also be the same method for doing the same with a barium sulphate solution with soluble impurities?
(edited 9 years ago)
Reply 10
Unfortunately, if it is the second case, method depends on the identity of the salt and identity of impurities - there is no general approach.

Perhaps the closest thing to general approach will be some kind of fractional crystallization.
Reply 11
Original post by Borek
Unfortunately, if it is the second case, method depends on the identity of the salt and identity of impurities - there is no general approach.

Perhaps the closest thing to general approach will be some kind of fractional crystallization.

Would it be wrong to just add a dilute acid to remove carbonate and hydroxide impurities? Or will it still leave other impurities?

Thank you, I appreciate your help :smile:
Reply 12
Original post by Peanut247
Would it be wrong to just add a dilute acid to remove carbonate and hydroxide impurities? Or will it still leave other impurities?


Adding acid is equivalent to contaminating the sample, isn't it?

Quick Reply

Latest