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Acid rain titration problem

  1. Apr 19, 2008 #1
    1. The problem statement, all variables and given/known data
    Estimate the volume of acid rain in L that can be neutralized by 1.00 g of limestone. Assume the pH of rainwater collected in your rain gauge is a representative value for acid rain. Assume that acid rain contains sulfuric acid as the source of hydrogen ions. The molecular weight of calcium carbonate is 100.09 g/mol.
    This is a question from my meteorology lab and I haven't had chemistry in 4 years, so I'm a bit rusty. Any help would be gladly appreciated!

    2. Relevant equations
    The net reaction between the two is
    H2SO4 + CaCO3 --> CaSO4H20 +CO2

    3. The attempt at a solution

    I know that we had 1.00 g CaCO3 and the molecular weight is 100.09. So I think I divide and plug this into the moles of CaCO3. Then our pH for the rainwater which would be 7.04, but I'm not really sure what to do with it since its not in mols?
    I'm pretty lost.
  2. jcsd
  3. Apr 19, 2008 #2


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    Do you remember the definition of pH?

    It's -log(molar concentration of H+ ions). You can use this to find the mols/L of H+ ions in the rain water.
  4. Apr 19, 2008 #3
    Ok so if I did this right, we have 9.12e-8 mol/L of H+ ions. Then we had 100.09 mols of CaCO3. I also know that the pH of the solution after neutralization is 4.36, but I don't really understand how to plug these into the equation since all of the units are different.
  5. Apr 20, 2008 #4


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    Homework Helper

    The pH of acid rain should be lower than 7 and that of the neutralized solution should be close to 7 please have this aspect clarified.

    Once you know the pH of the acid rain solution find the [H3O+] by using the pH equation. Also it must be assumed that the pH is mainly due to the first acidic proton of Sulfuric Acid = H2SO4 if this is the case then the [H3O+]=[H2SO4]. Otherwise we need to employ some equilibrium theory.

    Convert the amount of CaCO3 into moles then use the stoichiometry of the net equation between CaCO3 and H2SO4 to find the amount of H2SO4 in moles. Remember that [H2SO4]=[moles of H2SO4/L of solution]. Use this mole value that you've found and divide it by the value of [H2SO4] you've found.
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