✔ 最佳答案
The question is not on buffer solution. This is because both Na+(aq) and Cl-(aq) ions do not react with water, H+(aq) ion or OH-(aq) ion.
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1.
[H+] = [HCl] = 0.1 M
pH = -log[H+] = -log(0.1) = 1
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2.
[H+] = 0.1 x (1/10) = 0.01 M
pH = -log[H+] = -log(0.01) = 2
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3.
H+(aq) + OH-(aq) → H2O(l)
mole ratio H+ : OH- = 1 : 1
Before reaction:
Initial no. of moles of H+(aq) ion = MV = 0.1 x 1 = 0.1 mol
Initial no. of moles of OH-(aq) ion = 0.09 mol
Obviously, H+(aq) ion is in excess, and OH-(aq) ion is the limiting reactant.
Final no. of moles of H+(aq) ion = 0.1 - 0.09 = 0.01 mol
Final volume = 1 dm3
Final [H+] = mol/V = 0.01/1 = 0.01 M
pH = -log[H+] = -log(0.01) = 2
