You are Here: Home

# Chemistry Question: Amount of Substances

Announcements Posted on
Last day to win £100 of Amazon vouchers - don't miss out! Take our quick survey to enter 24-10-2016
1. ..
2. (Original post by mandeep_nagra)
10.0g of a mixture of sodium hydroxide and sodium chloride were dissolved in water. This mixture was titrated with sulfuric acid of concentration 0.500 mol dm-3. 52.10cm^3 of the acid was required for neutralisation. The equation as follows of:

2NaOH + H2SO4 ---> Na2SO4 + 2H2O

1) Calculate the number of moles of sulfuric acid required for neutralization
2)Hence deduce the number of moles of sodium hydroxide in the solution
3)Calculate the mass of sodium hydroxide
4) Hence find the percentage of sodium hydroxide in the original sample

Thank you
If I had a pen and paper with me I could've figured out the answers but check out Tyler de Witt's YouTube videos on the mole to help u with this. Trust me this stuff isn't hard
Good luck!!! ( I actually thought our teacher was teaching us GCSE stuff cos he was lazy but I guess GCSE mole does really come in to the a level spec)
Remember u need to divide by 2000 to get from cm^3 to dm^-3 and concentration*volume=mole
3. (Original post by mandeep_nagra)
10.0g of a mixture of sodium hydroxide and sodium chloride were dissolved in water. This mixture was titrated with sulfuric acid of concentration 0.500 mol dm-3. 52.10cm^3 of the acid was required for neutralisation. The equation as follows of:

2NaOH + H2SO4 ---> Na2SO4 + 2H2O

1) Calculate the number of moles of sulfuric acid required for neutralization
2)Hence deduce the number of moles of sodium hydroxide in the solution
3)Calculate the mass of sodium hydroxide
4) Hence find the percentage of sodium hydroxide in the original sample

Thank you
1) 0.02605
2) 0.0521
3) 2.08g
4) 20.8%
4. (Original post by mandeep_nagra)
Thank you
1) So you'll want to calculate the moles of Sulphuric acid used in the titration, and for this you use the equation: Moles = Vol. x concentration, making sure that you have the correct units, so you'll have to convert the volume to dm^3, so times it by 1x10^-3.
2) The acid and base react in a 1:2 ratio, so for every mole of acid you neutralise two moles of the hydroxide, hence you have twice the number of moles of NaOH.
3) To calculate the mass, you multiply the moles by the molecular weight of NaOH, which is 40.
4) You have 10g of the mixture, so to find the percentage you divide the mass of NaOH by the overall mass, and multiply by 100.

Summary:
Moles = Vol. x Conc
2:1 ratio, so double the number of moles
Mass = Mr x moles
(Mass of NaOH/Mass of substance)x100 = Percentage.

## 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: October 9, 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

### How does exam reform affect you?

From GCSE to A level, it's all changing

### Q&A with Paralympian Jack Rutter

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.