Questions: Calculate the grams of solute needed to prepare each of the following. Part B 4.30 L of a 0.200 M CaCl2 solution Express your answer with the appropriate units.

Solution Steps

To find the grams of solute needed, we first need to determine the number of moles of \(\mathrm{CaCl}_{2}\) required. We use the formula for molarity:

\[ M = \frac{\text{moles of solute}}{\text{volume of solution in liters}} \]

Given:

• Molarity (\(M\)) = 0.200 M
• Volume (\(V\)) = 4.30 L

Rearranging the formula to solve for moles of solute:

\[ \text{moles of solute} = M \times V = 0.200 \, \mathrm{M} \times 4.30 \, \mathrm{L} = 0.860 \, \text{moles} \]

Next, we need the molar mass of \(\mathrm{CaCl}_{2}\):

\[ \text{Molar mass of } \mathrm{CaCl}_{2} = \text{molar mass of } \mathrm{Ca} + 2 \times \text{molar mass of } \mathrm{Cl} \]

Using the periodic table:

• Molar mass of \(\mathrm{Ca}\) = 40.08 g/mol
• Molar mass of \(\mathrm{Cl}\) = 35.45 g/mol

\[ \text{Molar mass of } \mathrm{CaCl}_{2} = 40.08 \, \text{g/mol} + 2 \times 35.45 \, \text{g/mol} = 110.98 \, \text{g/mol} \]

Finally, we convert the moles of \(\mathrm{CaCl}_{2}\) to grams using its molar mass:

\[ \text{grams of } \mathrm{CaCl}_{2} = \text{moles of } \mathrm{CaCl}_{2} \times \text{molar mass of } \mathrm{CaCl}_{2} \]

\[ \text{grams of } \mathrm{CaCl}_{2} = 0.860 \, \text{moles} \times 110.98 \, \text{g/mol} = 95.438 \, \text{g} \]

Final Answer