What is the mass percent of water in Ca(NO3)2 · 4 H2O? Provide your answer to two decimal places.

• A. 18.95%
• B. 36.07%
• C. 12.56%
• D. 24.42%

Answer: (D)

Verified step by step guidance

1. Identify the chemical formula of the compound: calcium nitrate tetrahydrate, which is \(\mathrm{Ca(NO_3)_2 \cdot 4H_2O}\).
2. Calculate the molar mass of each component: first find the molar mass of \(\mathrm{Ca(NO_3)_2}\) by adding the atomic masses of calcium (Ca), nitrogen (N), and oxygen (O) atoms in the formula.
3. Calculate the molar mass of the water molecules: since there are 4 water molecules, multiply the molar mass of one water molecule (\(\mathrm{H_2O}\)) by 4.
4. Add the molar mass of \(\mathrm{Ca(NO_3)_2}\) and the molar mass of the 4 water molecules to get the total molar mass of \(\mathrm{Ca(NO_3)_2 \cdot 4H_2O}\).
5. Calculate the mass percent of water using the formula: \(\text{Mass \% of water} = \left( \frac{\text{Molar mass of 4 } H_2O}{\text{Molar mass of } Ca(NO_3)_2 \cdot 4H_2O} \right) \times 100\).