Stoichiometry; calculation headaches

AI Thread Summary
The discussion revolves around calculating the number of moles of HCl that reacted with 2.5g of impure CaCO3. The user initially calculated the moles of HCl in the solution and the moles of NaOH needed for titration but faced difficulties in determining the concentration of Solution X. After receiving hints on the next steps, they successfully solved the problem by determining the excess HCl present. The conversation highlights the challenges of stoichiometry calculations and the importance of peer assistance in resolving complex chemistry problems. Overall, the user found the process tricky but ultimately manageable with guidance.
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Hi, I've been trying and trying but I can't seem to solve this. Hopefully, there's someone here kind enough to help me through :X

2.5g of impure CaCO3 was dissolved in 25.0cm^3 of 2.00 mol dm^-3 HCL in a 100cm^3 volumetric flask and made up to the mark with distilled water. This solution is labelled as Solution X. 15.0cm^3 of this mixture required 20.0cm^3 of 0.0500 mol dm^-3 NaOH for neutralization.



Calculate the number of moles of HCL that has reacted with 2.5g of CaCO3.



1. I calculated the mole of HCL in 25.00cm^3 of 2.00 mol dm^-3 solution and also the number of moles of NaOH required to be titrated with 25cm^3 of the mixture of X.
2. I then tried calculating the concentration of Solution X that contains excess HCL. However, I got stuck there. If anyone could just hint me the next step, I would greatly appreciate it! thanks:)
 
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How many moles of HCl initially?

How many moles of NaOH reacted with the excess HCl?

How much of the excess HCl was present?

Then it is just initial minus excess.
 
thanks! I managed to solve it. a lil tricky though (:
 
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