You are Here: Home

# OCR Salters Calculation Help!!! watch

1. I've got two questions that i'm having trouble on from the Jan 05 Chemistry of Materials paper. Any help would be much appreciated! Thanks!

1) 2.00g of impure acetaminophen contains 0.010 mol acetaminophen. Calculate the percentage by mass of acetaminophen in the impure sample.

Ar of acetaminophen is 151

2) The amount of nickel(II) ions in a solution can be found by titrating with a solution of edta4- of known concentration using a suitable indicator.

25.0 cm³ of a solution containing nickel(II) ions reacted with exactly 22.0 cm³ of 0.100 mol dm-3 of edta4- ions.

Calculate the concentration of nickel(II) ions in the solution.

I'm having real problem with titrations so all help is welcome.
2. 1 mole acetaminophen = 151g
0.01 moles = 1.51g
1.51/2 x 100 = 75.5%
3. The amount of nickel(II) ions in a solution can be found by titrating with a solution of edta4- of known concentration using a suitable indicator.
25.0 cm³ of a solution containing nickel(II) ions reacted with exactly 22.0 cm³ of 0.100 mol dm-3 of edta4- ions.
Calculate the concentration of nickel(II) ions in the solution.

Ok so nickel is a 2+ ion and edta is a 4-
That means they'll react in a 2:1 ration
In 22cm3 of 0.1moldm-3 solution you're gonna have 0.1 x 0.022dm3 of mols = 0.0022mol
If you need 2 nickel for every 1 edta then you'll need 0.0044mol of nickel

You have 25cm3 which is 0.025dm3 of solution so the concentration is

0.0044 / 0.025 = 0.176mol/dm3

Happy with that now?
4. Yes!! Thanks!! How come it seems so much easier when someone explains them to me? lol!
5. Hehe it always does
It's like me with vectors
Gimme a worked example and i can totally see it
Give me a math question with vectors in and i go

### Related university courses

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:
Updated: June 19, 2005
The home of Results and Clearing

### 1,534

people online now

### 1,567,000

students helped last year
Today on TSR

### University open days

1. Keele University
Sun, 19 Aug '18
2. University of Melbourne
Sun, 19 Aug '18
3. Sheffield Hallam University