Question

a solution is made by mixing 50 ml of 2.0 m k₂hpo₄ and 25 ml of 2.0 m kh₂po₄. the solution is diluted to a final volume of 200 ml. what is the ph of the final solution?

Answer 1

To find the pH of the final solution, we need to calculate the moles of each compound, determine the total moles, and use the Henderson-Hasselbalch equation to calculate the pH.

Step-by-step explanation:

To find the pH of the final solution, we first need to calculate the moles of each compound present. Moles = volume (L) x molarity (mol/L).

For K2HPO4: Moles = 0.05 L x 2.0 mol/L = 0.10 mol

For KH2PO4: Moles = 0.025 L x 2.0 mol/L = 0.05 mol

Next, we need to determine the total moles of the final solution by summing up the moles of both compounds: Total Moles = 0.10 mol + 0.05 mol = 0.15 mol

Finally, we can calculate the pH of the solution using the equation pH = -log[H+]. Since the solution contains HPO42- and H2PO4- ions, we choose the ratio of [H2PO4-]/[HPO42-] that corresponds to a pH higher than 7. Based on the Henderson-Hasselbalch equation, when [H2PO4-]/[HPO42-] = 10, the pH is 6.06.