Question

How many moles of K+ & PO4^3- ions are present in 20.0 mL of a 0.015 M solution of potassium phosphate?

Answer 1

9.0 × 10⁻⁴ mol of K⁺

3.0 × 10⁻⁴ mol of PO₄³⁻

Step-by-step explanation:

Step 1: Calculate the moles of potassium phosphate in 20.0 mL of a 0.015 M solution

`0.0200 L * (0.015mol)/(L) = 3.0 * 10^(-4) mol`

Step 2: Write the balanced dissociation reaction

K₃PO₄(aq) ⇒ 3 K⁺(aq) + PO₄³⁻(aq)

Step 3: Calculate the moles of K⁺

The molar ratio of K₃PO₄ to K⁺ is 1:3. The moles of K⁺ are 3/1 × 3.0 × 10⁻⁴ mol = 9.0 × 10⁻⁴ mol

Step 4: Calculate the moles of PO₄³⁻

The molar ratio of K₃PO₄ to PO₄³⁻ is 1:1. The moles of PO₄³⁻ are 1/1 × 3.0 × 10⁻⁴ mol = 3.0 × 10⁻⁴ mol