You are Here: Home

Announcements Posted on
Four hours left to win £100 of Amazon vouchers!! Don't miss out! Take our short survey to enter 24-10-2016
1. So this was a question on the June 2015 paper. I'm not terrible at maths but I still couldn't figure this out. Someone please explain this to me properly before I start crying:

Calculate the mass of cyclohexanol needed to obtain 10.0g if cyclohexane if the yield is 75%.
2. (Original post by slaya)
So this was a question on the June 2015 paper. I'm not terrible at maths but I still couldn't figure this out. Someone please explain this to me properly before I start crying:

Calculate the mass of cyclohexanol needed to obtain 10.0g if cyclohexane if the yield is 75%.
It's a 1 to 1 reaction.

In other words 1 mol of cyclohexanol makes 1 mol of cyclohexene (I'm assuming a typo)

Calculate mol of cyclohexene in 10g by dividing by the Mr

Then calculate the mass of cyclohexanol which has this number of moles

This value represents 75% so now scale up the mass to 100%
3. What exam board?

Posted from TSR Mobile
1. the experimental yield(amount you obtained) is 10g
2. the theoretical yield (amount your supposed to get..'x')
3. yield=(experimental yield/Theoretical yield)X100
4. Therefore (10/x)X100=75
5. x=13.3g (that means you have put in enough cyclohexanol to make 13.3g of cyclohexane)
6. soo now u just calculate the number of moles of cyclohexane in 13.3g, that number of moles is equal to the number of moles of cyclohexanol put in (1:1 ratio)
7. then moles=mass/molar mass is used to calculate the mass of cyclohexanol in (the number of moles u found earlier)
THERE U GO!! it sounds a bit long but its quite easy just do like 2-3 sums of this type...keep repeating this until u completely understand it
hope i helped...i hated this question but now i love it... theres a similar one in the 2016 JAN Unit 3 IAL AS paper also just try that as well

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
2. this can't be left blank
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
1. Oops, you need to agree to our Ts&Cs to register

Updated: May 13, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### Who is getting a uni offer this half term?

Find out which unis are hot off the mark here

### How to get a 1st class degree

Poll
Study resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.