Assignment: Water
1. When 0.1 g of urea (MV = 60) is diluted to 100 mL with water, what is the osmotic
pressure of the solution? (Assume that the temperature is 25 °C)
2. Estimate the osmotic pressure of a solution of 0.1 M NaCl at 25 C. Assume 100%
ionization of solute?
3. Calculate the pH of a mixture of 0.25 M acetic acid and 0.1 M sodium acetate. pKa of
acetic acid is 4.76.
4. What is the pH in the preceding problem if the mixture consists of 0.1 M acetic acid
and 0.25 M sodium acetate?
5. Calculate the ratio of lactic acid and lactate required in a buffer system of pH 5.00.
The pKa of lactic acid is 3.86
6. During fermentation of wine, a buffer system consisting of tartaric acid and potassium
hydrogen tartrate is produced by biochemical reaction. Assuming that at some time
the concentration of potassium hydrogen tartrate is twice that of tartaric acid,
calculate the pH of the wine. pKa of tartaric acid is 2.96.
7. What is the pH of a solution prepared by mixing 150 ml of 0.1 M HCl with 300 ml of
0.1 M sodium acetate (NaOAc) and diluting the mixture of 1 L? The pKa of acetic
acid is 4.76.
8. What would be the effect of adding an additional 50 ml of 1.0 M HCl to the solution
in problem 7 before diluting to 1 L?