How many moles were required to prepare 500mL of a 0.45M
calcium chloride solution?

0.225 moles

Explanation:

Calcium chloride has a chemical formula of CaCl2

Given that,

Amount of moles of CaCl2 (n) = ?

Volume of aqeous solution (v) = 500mL

[Convert volume in milliliters to liters

If 1000mL = 1L

500mL = Z

cross multiply

Z x 1000mL = 1L x 500mL

Z = 500mL•L / 1000mL

Z = 0.5L]

Concentration of CaCl2 solution (c) = 0.45M

Since concentration (c) is obtained by dividing the amount of solute dissolved by the volume of solvent, hence

c = n / v

make n the subject formula

n = c x v

n = 0.45M x 0.5L

n = 0.225 moles

Thus, 0.225 moles were required to prepare 500mL of a 0.45M calcium chloride solution

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it is b that is the answer.