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A .500 g sample of impure CaO (a solid) is added to 50.0 mL of 0.100 M HCl. The excess HCl is titrated by 5.00 mL of .125 M NaOH. What is the percentage of CaO in the sample?

  • chemistry -

    CaO + 2HCl ==> CaCl2 + H2O

    mols HCl to start = M x L = ?
    mols HCl excess = M x L = 0.125 M x 0.005 L = ?
    Subtract. The difference is mols HCl used by the CaO.
    mols CaO = 1/2 mols HCl (the coefficients tell you that).
    g CaO = mols x molar mass
    %CaO = (mass CaO/ mass sample)*100 = ?

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