Question

63.15 mL of calcium hydroxide is required to titrate 18.9 mL of a 0.200 M H3PO4 solution. What is the molarity of the basic solution?

Answer 1

Answer:

0.0898M is the molarity of the basic solution

Explanation:

The reaction of calcium hydroxide, Ca(OH)₂ with H₃PO₄ is:

3 Ca(OH)₂ + 2 H₃PO₄ → 6H₂O + Ca₃(PO₄)₂

To solve this question we must find the moles of H3PO4 that react. With the moles and the rection we can find the moles of Ca(OH)2. Using its volume we can find its molarity:

Moles H3PO4:

0.0189L * (0.200mol / L) = 0.00378 moles H3PO4

Moles Ca(OH)2:

0.00378 moles H3PO4 * (3mol Ca(OH)2 / 2mol H3PO4) = 0.00567 moles Ca(OH)2

Molarity:

0.00567 moles Ca(OH)2 / 0.06315L =

0.0898M is the molarity of the basic solution