To determine the mass of CaCl₂ needed, we can follow a step-by-step approach:
1. Determine the total volume of the solution:
- Given: Each beaker must have 250 mL of solution and there are 10 beakers.
- First, we convert 250 mL to liters since the molarity is given in terms of liters.
[tex]\[
250 \text{ mL} = 0.250 \text{ liters}
\][/tex]
- Thus, for 10 beakers:
[tex]\[
\text{Total volume} = 10 \times 0.250 \text{ liters} = 2.5 \text{ liters}
\][/tex]
2. Calculate the moles of CaCl₂ required:
- The molarity (M) is given as 0.720 M, which means there are 0.720 moles of CaCl₂ in 1 liter of solution.
- To find the number of moles in 2.5 liters:
[tex]\[
\text{Moles of CaCl₂} = \text{Molarity} \times \text{Total volume}
\][/tex]
[tex]\[
\text{Moles of CaCl₂} = 0.720 \text{ M} \times 2.5 \text{ liters} = 1.8 \text{ moles}
\][/tex]
3. Calculate the mass of CaCl₂ required:
- Given: The molar mass of CaCl₂ is 110.98 g/mol, which means each mole of CaCl₂ weighs 110.98 grams.
- To find the mass for 1.8 moles:
[tex]\[
\text{Mass of CaCl₂} = \text{Moles of CaCl₂} \times \text{Molar mass}
\][/tex]
[tex]\[
\text{Mass of CaCl₂} = 1.8 \text{ moles} \times 110.98 \text{ g/mol} = 199.764 \text{ grams}
\][/tex]
Hence, the mass of CaCl₂ that would be used is approximately 200 g.
Thus, the correct answer is: [tex]$200 g$[/tex].
