So that makes the solution acidic.Now the concentration of the acid will be 0.001 mol / 0.040 L = 0.025 mol/LpH = -log(0.025) = 1.......
So 0.003 - 0.002 is 0.001 mol in excess. So that makes the solution acidic.
Now the concentration of the acid will be 0.001 mol / 0.040 L = 0.025 mol/L
pH = -log(0.025) = 1.6
OK?
You were right up to a point. You were correct in calculating the number of moles of Ba(OH)2 as 0.0010 mol, and that of nitric acid as being 0.0030 mol. However, the equation shows that for each mole of barium hydroxide, two moles of nitric acid is required. (See the coefficients of each.) Therefore, to neutralize 0.0010 mol of Ba(OH)2, twice as many moles or 0.0020 mol of HNO3 is needed. Since as much as 0.0030 mol of nitric acid is available, 0.0020 mol of nitric acid will be left unreacted. This means that 0.0020 mol of hydrogen ions will be left over. The molar concentration of H^+ ions is
[H^+] = (0.0020 mol) / (0.0400 L)
[H^+] = 2.5 × 10^-2 M
pH = – log [H^+]
pH = – log [2.5 × 10^-2]
pH = – [–1.602059991]
pH = 1.60
The above answer agrees with the answer given.
