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Chemistry - HELP!!

hey :smile:

Im studing for my GCSE Chemisty and the exam is in 25 days - it sounds like a long time I am really struggling and I'm begining to stress because my exam all start in a week and I still dont undertand!!
I've been doing loads of revison but there are some topics that I just cannot get my head around :/ I was wondering if someone could explain it to me....

- Titration Calculations and why you do a titration (what is the point in them) ... I am clueless where to start with these (We did some questions in class and I go 0 on all of them)

- Theoretical yeild .... Its probably really simple but I dont understand


Also, if anyone has any helpful tips about how to remember all of it as well as the functional groups of the different things (alkanes, alcohols, carboxylic acids, esters) that would be FANTASTIC!!

Thank you :biggrin:
Reply 1
Avatar for George_
George_
2
To do titration questions (finding the unknown concentration of a substance): find the moles of the substance with known concentration and volume using no. moles = c * v. Then, using c = no. moles/volume, you've got yourself the concentration!

Percentage Yield: useful product/total product * 100

Dunno if I've helped.
Reply 2
Avatar for amydowse
amydowse
OP
1
Thanks :smile: I now get why you do them... always a good start!!

So... what is the difference between moles and g/dm3 ... all the questions I've seen have been in cm3, g/dm3 and g :/

Oh!!! I now see what percentage yeild is... how do you work out the theoretical yeild though :/

These are probably really easy things but chemistry is hard!!! :frown:
Reply 3
Avatar for Danny786
Danny786
10
Get a CGP book, they're excellent and help a lot.

What is your exam board?
Reply 4
Avatar for amydowse
amydowse
OP
1
Original post by Danny786
Get a CGP book, they're excellent and help a lot.

What is your exam board?



I have a CGP revision and it is really helpful for most of it :biggrin: but I just dont understand some parts
Im with OCR :smile:
from the ocr chemisrty specification , does a higher tier person only needs to learn the higher and standard tier outcomes and not the foundation tier outcome, im not sure and my exam is next months and i still need to start my revision but not sure how much i need to learn.
Reply 6
Avatar for amydowse
amydowse
OP
1
Original post by haseebi82
from the ocr chemisrty specification , does a higher tier person only needs to learn the higher and standard tier outcomes and not the foundation tier outcome, im not sure and my exam is next months and i still need to start my revision but not sure how much i need to learn.



I'm not sure :/ Im just taking the specification from the website and using that as a check list for what I need to know - I think that will cover everything then

If your not sure, I would ask my teacher :smile:

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