About buffer solution in chemistry

用戶192275

2008-05-19 1:40 am

1.Calculate the ph of a solution containing 0.1M NaCl and 0.1M HCl

2.When the solution in 1. is diluted 10 fold, what is the ph value?

3.When 0.09 mole of NaOH solid is added to 1dm3 of the solution in 1.,calculate the final ph value.(assuming no change in volume)

我想要步驟thx

更新1:

我想要解釋thx

回答 (1)

Uncle Michael

2008-05-19 3:12 am

✔ 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.

=====
1.
[H+] = [HCl] = 0.1 M
pH = -log[H+] = -log(0.1) = 1

=====
2.
[H+] = 0.1 x (1/10) = 0.01 M
pH = -log[H+] = -log(0.01) = 2

=====
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

👍 0 👎 0