How does moles/conc change during titration between aliquots etc? (1 Viewer)

[SadCeliac]

If I have a 10mL sample diluted up to 250mL using distilled water, and then take a 20mL aliquot of that - what is the best way to work out final concentration given the moles in that aliquot??? I always get confused and end up with a miscalculation...

This is my understanding: 10mL sample --> 250mL (# moles don't change, conc changes) --> 20mL aliquot (# moles changes, conc doesn't change)

But then I still mess up using c1v1=c2v2...

Please help!!

 

[nsw..wollongong]

UR EXAM IS TODAY

 

[indeed]

If I have a 10mL sample diluted up to 250mL using distilled water, and then take a 20mL aliquot of that - what is the best way to work out final concentration given the moles in that aliquot??? I always get confused and end up with a miscalculation...

This is my understanding: 10mL sample --> 250mL (# moles don't change, conc changes) --> 20mL aliquot (# moles changes, conc doesn't change)

But then I still mess up using c1v1=c2v2...

Please help!!

Your second paragraph understanding is seems all right, but yh the calc also stumps me

I remember doing a question when working backwards you have to find the moles in your 20mL aliquot, times it by 250/20 (so 12.5) to get the moles in the 250mL, then you can do c = n/v (n being what you just found, v being 10mL sample converted to L)

 

[SadCeliac]

UR EXAM IS TODAY

I KNOW

 

[SadCeliac]

Your second paragraph understanding is seems all right, but yh the calc also stumps me

I remember doing a question when working backwards you have to find the moles in your 20mL aliquot, times it by 250/20 (so 12.5) to get the moles in the 250mL, then you can do c = n/v (n being what you just found, v being 10mL sample converted to L)

ohhhhh okay yep got it

 

[synthesisFR]

Just get good

 

[nsw..wollongong]

Just get good

the hypocrisy