Question #07316
2 Answers
Explanation:
First we find how many moles of
So:
So initial moles
(its mmol since there are 1000ml in 1L)
The alkali neutralises the acid:
This tells use that for every mole of
The no. moles
So the no. moles
The new volume
So the concentration of
So:
The pH will be
Explanation:
You're titrating hydrochloric acid,
So right from the start, you know that if the neutralization is complete, the pH of the solution will be equal to
But is the equivalence point reached or not?
The balanced chemical equation for this neutralization reaction is
#"HCl"_text((aq]) + "KOH"_text((aq]) -> "KCl"_text((aq]) + "H"_2"O"_text((l])#
The
If you have fewer moles of base, the solution will remain acidic, which means that you can expect to have
If you have more moles of base, the solution will become basic, which corresponds to
Use the molarities and volumes of the two solution to find the number of moles of each
#n = C/V implies n = C * V#
#n_(HCl) = "0.723 M" * 25.0 * 10^(-3)"L" = "0.01808 moles HCl"#
and
#n_(KOH) = "0.273 M" * 10.0 * 10^(-3)"L" = "0.002730 moles KOH"#
This means that the reaction will completely consume the added potassium hydroxide, leaving you with
#n_(HCl) = 0.01808 - 0.002730 = "0.01535 moles HCl"#
Since hydrochloric acid is a strong acid, it dissociates completely in aqueous solution to produce hydrogen ions,
This means that the number of moles of hydrogen ions you have in solution will be equal to the number of moles of hydrochloric acid (
The total volume of the solution will be
#V_"total" = v_(HCl) + V_(KOH)#
#V_"total" = 25.0 + 10.0 = "35.0 mL"#
The molarity of the hydrogen ions will be
#["H"^(+)] = "0.01535 moles"/(35.0 * 10^(-3)"L") = "0.4386 M"#
The pH of the solution will thus be
#pH_"sol" = -log(["H"^(+)]) = - log(0.4386) = color(green)(0.358)#