A buffer of pH 4 is prepared by adding 0.14g of solid sodium ethaonate to 0.1l of 0.1mol/l ethanoic acid.
What will be the new pH if 2.2 mL of HCl are added?
If 4.5mL of NaOH are added?
2007-06-19 05:42:00 · 3 answers · asked by jenna k 1 in Science & Mathematics ➔ Chemistry
Molar mass CH3COONa = 82 g/mol
Moles CH3COONa = 0.14 g / 82 = 0.00171
[CH3COONa]= 0.00171 / 0.1 = 0.0171 M
Ka = 1.8 x 10^-5
pKa = - log 1.8 x 10^-5 = 4.74
pH = pKa + log [CH3COO+]/ [ CH3COOH ] =
= 4.74 + log 0.0171 / 0.1 = 3.97
The effect of the added HCl would be to decrease the moles of CH3COO- and increase the moles of CH3COOH.
But I have to know MOLARITY of HCl to get pH
In the same way the effect of the added NaOH would be to increase the moles of CH3COO- and decrease the moles of CH3COOH , but I have to know the molarity of NaOH
2007-06-19 05:56:54 · answer #1 · answered by Dr.A 7 · 0⤊ 0⤋
depends on what the normality is of the HCL/NaOH
2007-06-19 12:50:19 · answer #2 · answered by NONAME 4 · 0⤊ 0⤋
pKb of Ch3COOH is required.
2007-06-19 13:01:59 · answer #3 · answered by ag_iitkgp 7 · 0⤊ 0⤋