1. Write the balanced chemical equation:

CaCN₂ (s) + 3H₂O (l) → CaCO₃ (s) + 2NH₃ (g)

2. Calculate the molar mass of CaCN₂ and H₂O:

* CaCN₂: 40.08 g/mol (Ca) + 12.01 g/mol (C) + 2 * 14.01 g/mol (N) = 80.10 g/mol

* H₂O: 2 * 1.01 g/mol (H) + 16.00 g/mol (O) = 18.02 g/mol

3. Convert grams of CaCN₂ to moles:

* moles of CaCN₂ = 74.0 g / 80.10 g/mol = 0.924 moles

4. Use the mole ratio from the balanced equation to find moles of H₂O:

* The equation shows that 1 mole of CaCN₂ reacts with 3 moles of H₂O.

* moles of H₂O = 0.924 moles CaCN₂ * (3 moles H₂O / 1 mole CaCN₂) = 2.772 moles H₂O

5. Convert moles of H₂O to grams:

* grams of H₂O = 2.772 moles * 18.02 g/mol = 50.0 g

Therefore, 50.0 grams of water are needed to react with 74.0 grams of CaCN₂.