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A solution of 0.45 M CaBr2 contains 0.027 moles of solute ions. What is the volume of the solution?
Title
A solution of 0.45 M CaBr 2 contains
Your Result
Correct
Difficulty
Hard
Your Pace
0:01
Others' Pace
2:11
Text Explanation
90.0 ml.: This answer choice is incorrect, because 90 ml would give you 0.113 moles of solute, not 0.027.
20.0 ml.: This answer choice is correct. 1 equivalent of CaBr2 will dissolve into 3 equivalents of solute:CaBr2(s) → Ca2+(aq) + 2Br-(aq)
Therefore, 0.45 moles/liter of CaBr2 will dissolve into 1.35 moles/liter of solute.
To find the volume, divide the number of moles of solute by solute molarity as follows:
(0.027 moles)/(1.35 moles/liter) = 0.02 liters = 20 ml.
250 ml.: This answer choice is incorrect, because 250 ml would give you 0.3375 moles of solute, not 0.027.
500 ml.: This answer choice is incorrect, because 500 ml would give you 0.675 moles of solute, not 0.027.
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