The Student Room Group
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>

AS Chemistry- helping each other out!

Scroll to see replies

Reply 1740
Avatar for Uwaiss
Uwaiss
Original post by Nidfeo
Sorry, I can't help you with ISA


Its from my CGP revision guide; shall I take a pic?
Original post by Dylann
Mol=conc/vol

Conc is 0.1 and volume is X. Put X in dm3 by dividing by 1000.

Mol=0.1/(X in dm3)

That is moles of NaOH. Since it's 1:1 ratio the moles of NaOH equals moles HCl.

Posted from TSR Mobile

n = cV not c/V

Think in units:
If moldm^-3/dm^3 was the case the ending unit would be moldm^-6 which is ridiculous.

edit: oops didn't know you're year 13 x.x sorreh
take this as a clarification for the original poster
(edited 8 years ago)
Original post by C0balt
n = cV not c/V

Think in units:
If moldm^-3/dm^3 was the case the ending unit would be moldm^-6 which is ridiculous.


Don't start on my *****, probs was just a typing error
Original post by Chocofudge123
Hi does anyone know the group 2 compound which is insoluble in water and gives of co2 and White sold when reacted with sulfuric acid?


Posted from TSR Mobile


Calcium carbonate?
Original post by frozo123
Don't start on my *****, probs was just a typing error

well he did it twice
better be safe than doing it again in exam
Original post by C0balt
well he did it twice
better be safe than doing it again in exam


he's in year 13
Original post by frozo123
he's in year 13

lol didn't notice
anyways for the benefit of the person who was asking :P
Original post by Uwaiss
My average titre if I was reckon was 30.9 would the calc be.. 0.1 / 0.0309? which is 3.09x10^-3?



Original post by C0balt
n = cV not c/V

Think in units:
If moldm^-3/dm^3 was the case the ending unit would be moldm^-6 which is ridiculous.

edit: oops didn't know you're year 13 x.x sorreh
take this as a clarification for the original poster


Wow I must have been half asleep when I wrote that! You're dead right, it's mol = conc x vol not conc/vol! mol = mass/mr

haha, we all make mistakes :colondollar:

Sorry Uwais, so yeah mol = conc x vol

conc = 0.01
vol = X

mol = 0.01 x X in dm-3
Original post by frozo123
he's in year 13


Doesn't mean I'm immune from making silly mistakes :wink:
Original post by Dylann
Doesn't mean I'm immune from making silly mistakes :wink:


Never said you were
hi guys I've had this nagging problem in chem for a while
say in the empa it asks you to work out a given value
say it comes to 109.89088987
`i round that to 3sf to get 110

Then in part(ii) it asks me hence to work out say percentage error for 100 the true value
Do i sub in my rounded answer of 110 or my accurate answer of 109.89088987 to get my answer for this part (ii) answer
thanks this has been annoying me for ages becos using my rounded answer could introduce rounding errors
Original post by chemphys
hi guys I've had this nagging problem in chem for a while
say in the empa it asks you to work out a given value
say it comes to 109.89088987
`i round that to 3sf to get 110

Then in part(ii) it asks me hence to work out say percentage error for 100 the true value
Do i sub in my rounded answer of 110 or my accurate answer of 109.89088987 to get my answer for this part (ii) answer
thanks this has been annoying me for ages becos using my rounded answer could introduce rounding errors


Keep your value in calculator and use it calculate the percentage error, then round the final to 3 sf (or whatever asked)

Posted from TSR Mobile
Original post by C0balt
Keep your value in calculator and use it calculate the percentage error, then round the final to 3 sf (or whatever asked)

Posted from TSR Mobile

ok thanks , but when showing your working do you write down the said value on the calculator becos technically the mark scheme says must use answer from part (i) and strictly speaking your 3sf answer was your final answer.

Will the examiner realise that when you write the exact answer in working it is the same as your answer for the previous part just not rounded?

Also do you do aqa thanks
Original post by chemphys
ok thanks , but when showing your working do you write down the said value on the calculator becos technically the mark scheme says must use answer from part (i) and strictly speaking your 3sf answer was your final answer.

Will the examiner realise that when you write the exact answer in working it is the same as your answer for the previous part just not rounded?

Also do you do aqa thanks


I do Edexcel
In my physics practical I wrote a sidenote that unrounded value was used just to make sure (it takes less than 5sec and not much space so why not)
I'm not sure the official view on this but my chem teachers tell me to write your rounded value on paper but use the calculator value
Need confirmation though, not 100% sure

Posted from TSR Mobile
Anyone doing the empa?
How are you preparing for task 3? I find it so hard!
Does this calculation look right?
Original post by Kadak
Does this calculation look right?


Which?

Posted from TSR Mobile
Original post by C0balt


The one in the picture.I'm.meant to show the standard enthalpy of change.
Original post by Kadak
The one in the picture.I'm.meant to show the standard enthalpy of change.


What picture?

Posted from TSR Mobile
Original post by Kadak
The one in the picture.I'm.meant to show the standard enthalpy of change.


There's no picture

Posted from TSR Mobile

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you