# Gr. 11. Titration problem (check if my answer is right)

## Homework Statement

The acidic waste from a student's experiment needs to be disposed of, but pouring it down the sink would increase the impact of acid rain on the local water supply. Explain how you could determine the amount of limestone needed to neutralize the environmental impact of the experiment. (Assume the that limestone is mainly calcium carbonate.)

Write a balanced equations for any reactions you intend to use.

## Homework Equations

H2SO4(aq) + CaCO3(s) --> H2O(l) + CO2(g) + CaSO4(s)

## The Attempt at a Solution

Steps:
1. measure the concentration of the acid and the volume of the acid
2. grain the lime stone into powder and measure the weight
3. add methyl red or other indicator into the acid
4. slowly add the lime stone powder bit by bit until the indicator colour changes
5. measure the weight of the remaining lime stone and subtract it from the initial weight to obtain the mass of lime stone used to neutralize the acid
6. Determine the mass of lime stone needed to neutralize each Litre of the acid

Is that right?
The problem is that the salt produced from this chemical reaction is a solid. Would this affect the result?
And it might be hard to accurately put lime stone into the acid.
Is there a better way or a more correct way to do it?
Thanks

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Homework Helper
Here's a general suggestion,

Take a fixed quantity of the acid waste solution and add some limestone to it until the pH exceeds 7 (which can be detected by using an appropriate chemical indicator or litmus paper); you need to use a sufficient concentration of the limestone so that there would be enough base content to neutralize the particular amount of the waste acid solution. After the required amount of limestone has been found, take another sample with the same mass, and dissolve it in sufficient amount of water. Use this solution as a titrant for the waste acid solution of the same volume as before and determine the volume of it required to neutralize the acid (after this, calculate the corresponding mass of the limestone that was required to neutralize this acid solution by correlating the volume ratio with the original total mass of limestone that was dissolved to make the stock solution).

From all of this experimentation, find the value of grams of limestone required/L of the acid waste solution.

Does limestone dissolve in water? I thought it couldn't.
If it can dissolve in water, can I just take a certain mass of limestone and dissolve it in certain amount of water. Then determine the amount need to neutralize 1 L of the acid. then just multiply it by th concentration of the limestone solution to obtain the mass of limestone?

ShawnD