CHM 152 Quiz April 24

# CHM 152 Quiz April 24 - .Fourofthemostcommon .0 of in225...

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The composition of a solution can be expressed in several different ways. Four of the most common concentration units are defined below. A solution was prepared by dissolving 34.0 of in 225 of water.

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Part A Calculate the mass percent of in the solution. Hint A.1 How to approach the problem Hint not displayed Part A.2 Determine the total mass of the solution Part not displayed Express the concentration numerically as a percent. ANSWER: Answer not displayed Part B Calculate the mole fraction of in the solution. Hint B.1 How to approach the problem Hint not displayed Part B.2 Convert mass of KCl to moles Part not displayed Part B.3 Convert grams of water to moles Part not displayed Part B.4 Determine the total number of moles in the solution Part not displayed Express the concentration numerically as a mole fraction. ANSWER: = Answer not displayed
Part C Calculate the molarity of in the solution if the total volume of the solution is 239 . Hint C.1 How to approach the problem Hint not displayed Part C.2 Convert the mass of KCl to moles Part not displayed Part C.3 Convert solution from milliliters to liters Part not displayed Express the concentration numerically as a molarity. ANSWER: Answer not displayed Part D Calculate the molality of in the solution. Hint D.1 How to approach the problem Hint not displayed Part D.2 Convert the mass of KCl to moles Part not displayed Part D.3 Determine the kilogram mass of the solvent Part not displayed Express the concentration numerically as a molality. ANSWER: Answer not displayed Colligative Properties of Electrolytes Colligative properties are those that depend on the number of solute particles. Because electrolytes dissociate into ions, the concentration of particles in the solution is greater than the concentration of the solution. For example, if 1 mole of totally dissociates, 3 moles of ions are produced (2 moles of ions and 1 mole of ions). Thus, a colligative property such as osmotic pressure will be three times greater for a 1 solution than for a 1 nonelectrolyte solution. However, complete dissociation of electrolytes does not always occur. The extent of dissociation is expressed by the van't Hoff factor, .

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The equations for colligative properties can be written to include . For example: Part A Assuming complete dissociation of the solute, how many grams of must be added to 275 of water to produce a solution that freezes at 14.5 ? The freezing point for pure water is 0.0 and is equal to 1.86 . Hint A.1 How to approach the problem Hint not displayed Part A.2 Assign a value to the van't Hoff factor Part not displayed Part A.3 Determine the freezing point depression of the solution Part not displayed Part A.4 Calculate the molality of the solution Part not displayed Part A.5 Determine the mass of solvent in kilograms Part not displayed Part A.6 Calculate the number of moles of solute Part not displayed Part A.7 Calculate the molar mass of potassium nitrate Part not displayed Express the mass numerically in grams. ANSWER:
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CHM 152 Quiz April 24 - .Fourofthemostcommon .0 of in225...

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