Question

How many grams of calcium phosphate can be produced when 78.5 grams of calcium hydroxide reacts with excess phosphoric acid?

Unbalanced equation: H3PO4 + Ca(OH)2 → H2O + Ca3(PO4)2

Show, or explain, all of your work along with the final answer.

Answer 1

Hello,


You balanced the equation and then you have to set up what is called a psychometric equation for each reactant so that you get the same unit for each in order to compare the two. so for (calcium hydroxide) = 78.5 g ÷ (40.1 + 32 + 2) = 1.0593 mol * Note: I just broke it down in my own science way..u can just get the molar mass of calcium hydroxide which is approx 74 g/mol


Hope this helps

Answer 2

109.56g

Step-by-step explanation:

H3PO4 + Ca(OH)2 → H2O + Ca3(PO4)2

The balanced equation is given as;

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

Molar mass of Ca(OH)2 = 74.092g/mol

But Number of moles = Mass / Molar mass = 78.5 / 74.092 = 1.0595 mol

From the reaction above,

3 mol of Ca(OH)2 produces 1 mol of Ca3(PO4)2.

1.0595 mo would produce x?

3 = 1

1.0595 = x

x = 1.0595 / 3 = 0.3532mol of Ca3(PO4)2

Mass of Ca3(PO4)2 = Number of moles * Molar mass = 0.3532 * 310.18 = 109.56g