Question

Calculate the pH of the solution consisting of 1200cm³ KOH solution with quantitative concentration 0.5 mol / dm3 and 800cm³ HCl solution with quantitative concentration 1 mol / dm3?

Answer 1

The pH of the solution can be calculated using the formula:

pH = -log(H^+)

After performing the necessary calculations, the pH is found to be approximately 1.30.

Step-by-step explanation:

To calculate the pH of the solution, we need to consider the contribution of both the hydroxide (OH^-) ions from KOH and the hydronium (H₃O^+) ions from HCl.

First, determine the moles of OH^- ions from the KOH solution:

Moles of OH^- = concentration × volume = 0.5 mol/dm³ × (1200 cm³ / 1000) = 0.6 mol

Next, determine the moles of H₃O^+ ions from the HCl solution:

Moles of H₃O^+ = concentration × volume = 1 mol/dm³ × (800 cm³ / 1000) = 0.8 mol

Since the reaction between OH^- and H₃O^+ forms water, the limiting reactant is the one in lower quantity, which is OH^-. Therefore, all OH^- ions will react with H₃O^+, leaving 0.2 mol of H₃O^+ in excess.

Finally, calculate the H^+ concentration from the excess H₃O^+ ions:

H^+ = 0.2 mol

Now, apply the formula for pH:

pH = -log(H^+) = -log(0.2) ≈ 1.30

Therefore, the pH of the solution is approximately 1.30.