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# Titration question watch

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1. 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.
2. Do you still need help with this question?
3. (Original post by High Stakes)
Do you still need help with this question?
yes
4. (Original post by 15076683)
yes
do you have the answer?
5. No. Sorry. I've written all the information I know
6. (Original post by 15076683)
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.
87.6%
7. (Original post by beansingit)
87.6%
8. (Original post by Remainresilient_)
Gonna upload one second.
9. (Original post by Remainresilient_)
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.

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

10. (Original post by High Stakes)
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.

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??
11. (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??
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.

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