± Introduction to Units of Concentration The composition of a solution can be expressed in several different ways. Four of the most common concentration units are defined as follows:.mass %=mass of componenttotal mass of solution×100% mole fraction (X)=moles of componenttotal moles of solution molarity (M)=moles of soluteliters of solution molality (m)=moles of solutemass of solvent (kg) 
A solution was prepared by dissolving 33.0 g of KCl in 225 g of water. Part A Calculate the mass percent of KCl in the solution. Express your answer with the appropriate units.
SubmitHintsMy AnswersGive UpReview Part Incorrect; Try Again; 4 attempts remaining Part B Calculate the mole fraction of the ionic species KCl in the solution. Express the concentration numerically as a mole fraction in decimal form.
SubmitHintsMy AnswersGive UpReview Part Incorrect; Try Again; 5 attempts remaining Part C Calculate the molarity of KCl in the solution if the total volume of the solution is 239 mL. Express your answer with the appropriate units.
SubmitHintsMy AnswersGive UpReview Part Part D Calculate the molality of KCl in the solution. Express your answer with the appropriate units.

part A )
solution mass = 33 + 225 = 258 g
mass % of KCl = 33 x 100 / 258 = 12.79 %
part B)
moles of KCl = 33/ 74.55 = 0.443
moles of H2O = 225 / 18 = 12.8
total moles = 0.443 + 12.8 = 12.94
mole fraction of KCl = 0.443 / 12.94 = 0.0342
moles fraction of ions = 0.0342
part C)
total volume = 239 mL = 0.239 L
molarity = moles / volume = 0.443 / 0.239
molarity = 1.85 M
part D)
molality = moles / mass of solvent
= 0.443 / 0.225
= 1.97 m
molality = 1.97 m
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