Question

exercise 5.56 - enhanced - with feedback

enter the formula for the compound that forms from calcium and hydroxide.
express your answer as a chemical formula.

part b
enter the formula for the compound that forms from calcium and carbonate.
express your answer as a chemical formula.

part c
enter the formula for the compound that forms from calcium and phosphate.
express your answer as a chemical formula.

Explanation:

Identify the ions for Part A

Determine the charges of calcium and hydroxide.

• Calcium is a Group 2 metal: \(\text{Ca}^{2+}\).
• Hydroxide is a polyatomic ion: \(\text{OH}^-\).

Balance the charges for Part A

Combine the ions to form a neutral compound.

• Two \(\text{OH}^-\) ions balance one \(\text{Ca}^{2+}\) ion.
• The formula is \(\text{Ca(OH)}_2\).

Identify the ions for Part B

Determine the charges of calcium and carbonate.

• Calcium is \(\text{Ca}^{2+}\).
• Carbonate is a polyatomic ion: \(\text{CO}_3^{2-}\).

Balance the charges for Part B

Combine the ions to form a neutral compound.

• One \(\text{CO}_3^{2-}\) ion balances one \(\text{Ca}^{2+}\) ion.
• The formula is \(\text{CaCO}_3\).

Balance the charges for Part C

Determine charges and combine calcium and phosphate.

• Calcium is \(\text{Ca}^{2+}\).
• Phosphate is \(\text{PO}_4^{3-}\).
• To balance, use three \(\text{Ca}^{2+}\) and two \(\text{PO}_4^{3-}\).
• The formula is \(\text{Ca}_3(\text{PO}_4)_2\).

Answer:

Part A

\(\text{Ca(OH)}_2\)

Part B

\(\text{CaCO}_3\)

Part C

\(\text{Ca}_3(\text{PO}_4)_2\)