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How many moles of CaCl2 are in 250mL of a 3.0M of CaCl2 solution?

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msipley | Student, Undergraduate | eNoter

Posted May 3, 2012 at 1:17 AM via web

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How many moles of CaCl2 are in 250mL of a 3.0M of CaCl2 solution?

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guavamangoes | Student, Grade 10 | eNotes Newbie

Posted May 3, 2012 at 3:21 AM (Answer #1)

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3.0 M = 3moles/1liter

250mL= 0.25 L

so, 3mol/1L= (?)mol/.25L

there are 0.75 moles of CaCl2 in 250 mL of a 3.0 molar solution

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sciencesolve | Teacher | (Level 3) Educator Emeritus

Posted May 9, 2012 at 6:49 AM (Answer #2)

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Since the problem provides the amount in liters of CaCl2 solutions, then 3.0M expresses the molarity of solution, hence you need to use the molarity formula such that:

M = (number of moles of CaCl2 solution)/(volume of CaCl2 in liters)

You need to convert the amount of 250 mL in liters such that:

250mL = 250*10^(-3)L

Substituting 3 for M and 250*10^(-3)L for V yields:

3 = N/(0.250) => N = 3*0.250

N = 0.75

Hence, evaluating the number of moles in 250mL of CaCl2 solution yields 0.75 moles.

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