Finding the percentage of composition in the mixture

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Discussion Overview

The discussion revolves around determining the percentage composition of a mixture containing magnesium carbonate (MgCO3) and calcium carbonate (CaCO3) through titration methods involving hydrochloric acid (HCl) and sodium hydroxide (NaOH). Participants explore the steps necessary to approach the problem, including calculations and assumptions related to the chemical reactions involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning
  • Homework-related

Main Points Raised

  • One participant expresses uncertainty about how to approach the problem and requests guidance on the steps needed to find relevant values.
  • Another participant suggests that titration with sodium hydroxide can reveal how much HCl remains after reacting with the carbonate mixture, proposing that calculating the amount of HCl that reacted with NaOH is a good starting point.
  • A participant questions whether the number of moles of MgCO3 and CaCO3 are equal, indicating uncertainty about the stoichiometry involved in the reaction.
  • It is noted that targeting only the carbonate may not provide sufficient information to determine the amounts of magnesium and calcium in the mixture.
  • A suggestion is made to assume variables for the moles of magnesium carbonate (x) and calcium carbonate (y) and to express the sample mass in terms of these variables.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the equality of moles of MgCO3 and CaCO3, and there are multiple competing views on how to approach the problem and the necessary calculations.

Contextual Notes

Participants have not resolved the assumptions regarding the stoichiometry of the reaction or the implications of the titration results on the composition of the mixture.

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Homework Statement
A mixture of calcium carbonate and magnesium carbonate weighs 2.36 g. It is dissolved in a 700 ml, 0.10 moles per cubic decimeter Hydrochloric solution. The resulting solution is then diluted up to 25 cubic decimeter with water. 20 ml of sodium hydroxide completely reacts with 25 ml of above prepared solution. Find the percentage composition of composition of the mixture.
Relevant Equations
C = n/v , C1V1=C2V2 , number of moles = mass/molar mass ..... I don't know what other equations appear here.
The thing is that, I don't know how to approach this question and the particular steps for relevant value findings. Please show me the path, and I will go in it friends. I couldn't attempt as I have no clue how to approach this. Thank you very much in advance.
 
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The titration with sodium hydroxide will tell you how much HCl remains in solution after reaction with the carbonate mixture. Therefore, a good starting point is to calculate how much HCl reacted with NaOH in the last step in order to infer how much HCl reacted with the carbonate mixture.
 
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Ygggdrasil said:
The titration with sodium hydroxide will tell you how much HCl remains in solution after reaction with the carbonate mixture. Therefore, a good starting point is to calculate how much HCl reacted with NaOH in the last step in order to infer how much HCl reacted with the carbonate mixture.

Yeah I did that, thank you very much. Hey are the number of moles of MgCO3 and number of moles of CaCO3 equal ? I could come to a solution but I don't know whether it is correct or not. Are the number of moles of the both equal?

What should I do after finding the excess amount of HCL present in the mixture that was diluted up to 25 dm3?
 
Targeting only for carbonate will not be enough information if you are looking for both how much Mg and how much Ca.
 
Assume x moles of magnesium carbonate and y moles of calcium carbonate.

Titration told you x+y.

Can you express sample mass with x, y?
 

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