Stuck on problem due tonight

Question

What is the pH and pOH of a solution made by adding water to 23.2 grams of calcium hydroxide until the volume of the solution is 2500 ? (Hint: solve for molarity first !

pOH?round to 1 decimal place

pH?round to 1 decimal place

Answer 1

To find the pH and pOH of the solution, we first need to calculate the molarity of calcium hydroxide in the solution.

Molarity = moles of solute / liters of solution

First, let's find the moles of calcium hydroxide:

molar mass of Ca(OH)2 = 74.093 g/mol moles of Ca(OH)2 = 23.2 g / 74.093 g/mol = 0.3132 mol

Next, let's calculate the liters of solution:

volume of solution = 2500 mL = 2.5 L

Now, we can find the molarity:

Molarity = 0.3132 mol / 2.5 L = 0.1253 M

Since calcium hydroxide is a strong base, it will dissociate completely in water to form calcium and hydroxide ions:

Ca(OH)2(s) → Ca2+(aq) + 2 OH-(aq)

The concentration of hydroxide ions can be found using the molarity of calcium hydroxide:

[OH-] = 2 × 0.1253 M = 0.2506 M

The pOH of the solution can be calculated as:

pOH = -log[OH-] = -log(0.2506) = 0.6028

The pH can be calculated from the pOH using the relation:

pH + pOH = 14

So,

pH = 14 - pOH = 14 - 0.6028 = 13.3972

Therefore, the pH of the solution is 13.4 (rounded to 1 decimal place) and the pOH is 0.6 (rounded to 1 decimal place).