Abuffer is prepared by mixing 204.0 ml of 0.452 mol/l hydrochloric acid (hci) and 500.0 ml of 0.400 mol/l sodium acetate (nachco2, naac). what is the ph of the above buffer solution?

pH of buffer is 4.81

Explanation:

The reaction between HCl and sodium acetate will product acetic acid. The presence of weak acid (acetic acid) and its salt will make a buffer.

The reaction will be:

Thus one mole each of HCl and acetate will give one mole of acetic acid.

The moles of HCl present = molarity X volume = 0.452 X 0.204 =0.092

moles of acetic acid formed on reaction of HCl with acetate = 0.092

Initial moles of sodium acetate present = molarity X volume = 0.4X0.5 =0.2

moles of sodium acetate left =0.108 mol

the pKa of acetic acid =4.74

The pH of buffer is calculated using Henderson Hassalbalch's equation :

pH = pKa + log

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%