Final answer:
To calculate the pH of a solution made by mixing 15 ml of 0.085 M NaOH with 135 ml of water, calculate the moles of NaOH, find the OH- concentration, determine the pOH, and use the 14 - pOH to find the pH. The resulting pH is approximately 11.07.
Step-by-step explanation:
To determine the pH of a solution created by mixing 15 ml of 0.085 M NaOH with 135 ml of distilled water, we can first calculate the moles of NaOH. Since NaOH is a strong base, it will dissociate completely in solution. The number of moles of NaOH is given by its concentration times its volume in liters (0.085 M × 0.015 L = 0.001275 moles).
When NaOH is dissolved in water, it increases the OH- concentration in the solution, and hence we can find the pOH of the solution. Since the total volume of the solution is 150 ml or 0.150 L, the OH- concentration in the solution will be 0.001275 moles ÷ 0.150 L = 0.0085 M. The pOH is calculated as the negative logarithm of the hydroxide ion concentration: pOH = -log(0.0085).
Finally, to find the pH, we use the relationship pH + pOH = 14. With the calculated pOH, we subtract it from 14 to find the pH of the solution. After calculating, we find the pH value to be approximately 11.07.