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OCR A Titration Calculations

Hello there!

I've been doing some titration styled practice questions to prepare us to what we will be doing in real ISA soon.

But I'm stuck on the Q.3,4,5!.If you could have a look at what I've done, and explain how you would progress onto the next question, it would be greatly appreciated!

Cheers in advance : )

PS: Information required to work out calculations(i.e titre volume, known substance concentration), are inserted in the pic below:

Reply 1

Brister

Original post by KiddingMe

Question 3
You can figure out the concentration of the diluted solution using the number of moles needed for the titration and the corresponding volume, 11.9 cm³. This allows you to work out the number of moles in the diluted 250 cm³.

Question 4
Notice that when you dilute the original solution, the number of moles of H₂SO₄ does not change; only the volume changes. Therefore the number of moles in (3) is what you use to find the original concentration.

Question 5
You just have to convert amount of H₂SO₄ to mass of H₂SO₄.

Reply 2

KiddingMe

So q3, is like a scaling calculation then? I'm still no wiser on Q5 though!

Cheers for the help though!

Reply 3

Brister

Original post by KiddingMe

So q3, is like a scaling calculation then? I'm still no wiser on Q5 though!

Cheers for the help though!

Yes precisely, you scale up because any sample of the solution will have the same concentration i.e. 250 cm³ of the solution will have 250 times as much of the compound as 1 cm³.

For part 5, you calculate the molar mass of H₂SO₄ and convert the number of moles to a mass in grams.