Titration question

1.0g of Limestone (calcium carbonate) is allowed to react with 100cm3 of 0.20M hydrochloric acid solution. When the reaction was complete, the excess acid remaining required 24.8cm3 of 0.10M sodium hydroxide solution for neutralisation. Calculate the percentage of calcium carbonate in the limestone.

Reply 1

High Stakes

Do you still need help with this question?

Reply 2

15076683

Original post by High Stakes

Do you still need help with this question?

yes

Reply 3

Remainresilient_

Original post by 15076683

yes

do you have the answer?

Reply 4

15076683

No. Sorry. I've written all the information I know :smile:

Reply 5

beansingit

Original post by 15076683

87.6%

Reply 6

Remainresilient_

Original post by beansingit

87.6%

Working please?

Reply 7

High Stakes

Original post by Remainresilient_

Working please?

Gonna upload one second.

Reply 8

High Stakes

Original post by Remainresilient_

Working please?

First write out all the relevant information and work out the moles of the two compounds that we can work out first. This will give us a lead or at least a cue on what to do next. Hope I helped. :smile:

I meant 1:2 ^ when I was talking about 1/2 - Sorry

(edited 8 years ago)

Reply 9

15076683

Original post by High Stakes

I meant 1:2 ^ when I was talking about 1/2 - Sorry

Thank you so much for the help! However, I do have a question: Cant you work out the moles of CaCO3 using the moles=mass/Mr considering it states there is 1.0g of limestone?? :smile:

Reply 10

High Stakes

Original post by 15076683

Thank you so much for the help! However, I do have a question: Cant you work out the moles of CaCO3 using the moles=mass/Mr considering it states there is 1.0g of limestone?? :smile:

The question asks how much of the limestone is CaCO3. What that means is that 1.0g of limestone is not completely CaCO3 (i.e. it contains something else which we don't care about).

If you worked out the moles using CaCO3 and 1.0g mass, you'd work out how many moles of CaCO3 there are in 1.0g of Limestone that is purely CaCO3 - Which isn't the case. :smile: