# Unit 7A Reading Problem 6 Homework

What is the balanced equation for Ca(OH)2 + H3PO4 → Ca3(PO4)2 + H2O?

To balance the equation Ca(OH)2 + H3PO4 → Ca3(PO4)2 + H2O, you need to place coefficients in front of each compound to ensure an equal number of each type of atom on both sides. The balanced equation is 3Ca(OH)2 + 2H3PO4 → Ca3(PO4)2 + 6H2O. The sum of the coefficients is 19.

## Explanation:

**To balance the equation Ca(OH)2 + H3PO4 → Ca3(PO4)2 + H2O,**we need to ensure that there are an equal number of each type of atom on both sides of the equation. Starting with the calcium (Ca) atoms, we have 1 on the left side and 3 on the right side, so we need to place a coefficient of 3 in front of Ca(OH)2. This gives us 3 Ca atoms on both sides. Next, let's balance the hydrogen (H) atoms. We have 6 on the left side (2 from Ca(OH)2 and 4 from H3PO4), so we need to place a coefficient of 6 in front of H3PO4. This gives us 6 H atoms on both sides. Finally, let's balance the phosphorus (P) and oxygen (O) atoms. We have 1 phosphorus atom on the left side and 2 on the right side, so we need to place a coefficient of 2 in front of Ca3(PO4)2. This gives us 2 P atoms on both sides. Lastly, we balance the oxygen atoms. We have 8 on the left side and 10 on the right side, so we need to place a coefficient of 5 in front of H2O. This gives us 10 O atoms on both sides. The balanced equation is: 3Ca(OH)2 + 2H3PO4 → Ca3(PO4)2 + 6H2O. The sum of the coefficients is 3 + 2 + 1 + 2 + 6 + 5 = 19.