# Titration of HCl with CaCO3, then excess HCl titrated with NaOH

• Chemistry
• i_love_science
In summary, the purpose of titrating HCl with CaCO3 is to determine the concentration of HCl in a solution. Excess HCl is added before titrating with NaOH to ensure an accurate endpoint, which is determined by adding an indicator. Titrating with NaOH after excess HCl is added allows for the determination of the amount of excess HCl present in the solution. The concentration of HCl can be calculated using the titration results and the known reaction between HCl and NaOH.
i_love_science
Homework Statement
50.0 cm3 of 1.00 mol dm-3 hydrochloric acid solution, HCl(aq) was added to a piece of pure marble, CaCO3 with a mass of 1.926 g. After all the marble had reacted the resulting solution was put into a 100 cm3 volumetric flask and the volume made up to the mark with distilled water. 10.0 cm3 of this solution was then titrated with 1.00 x 10-1 mol dm-3sodium hydroxide solution, NaOH(aq). Calculate the volume of the sodium hydroxide solution required to neutralise exactly the excess acid present in this 10.0 cm3 sample during this titration.
Relevant Equations
titration
There is 0.019243 mol of CaCO3, and therefore 0.038485 mol of HCL. There is 0011505 mol of HCl in excess after reacting it with CaCO3. The concentration of HCl after water is added is 0.11515 mol/dm3. There is 0.0011515 mol of HCl in 10 cm3 of the new solution, and the same number of moles of NaOH reacted.

I got 0.0115 L of NaOH as my final answer, is it correct? Thanks.

Looks OK to me.

## 1. What is the purpose of titrating HCl with CaCO3?

The purpose of titrating HCl with CaCO3 is to determine the amount of HCl present in a solution. CaCO3, also known as calcium carbonate, is a base that reacts with HCl in a 1:2 ratio. By measuring the amount of CaCO3 used to neutralize the HCl, the concentration of HCl can be calculated.

## 2. Why is excess HCl added after titrating with CaCO3?

Excess HCl is added after titrating with CaCO3 to ensure that all of the CaCO3 has reacted and no excess base is present. This allows for a more accurate measurement of the amount of HCl present in the solution.

## 3. What is the purpose of titrating the excess HCl with NaOH?

The purpose of titrating the excess HCl with NaOH is to determine the amount of excess acid present in the solution. NaOH is a strong base that reacts with HCl in a 1:1 ratio. By measuring the amount of NaOH used to neutralize the excess HCl, the amount of excess acid can be calculated.

## 4. How does the titration process work?

In the titration process, a known volume of HCl is added to a solution containing CaCO3. The CaCO3 reacts with the HCl, producing CO2 gas and water. The solution is then titrated with NaOH to determine the amount of excess HCl present. The endpoint of the titration is reached when the solution turns from acidic to basic, indicating that all of the HCl has been neutralized.

## 5. What factors can affect the accuracy of the titration results?

The accuracy of the titration results can be affected by factors such as human error, impurities in the chemicals used, and incorrect measurements of volume or concentration. It is important to carefully follow the procedure and use precise measuring equipment to obtain accurate results.

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