Chemistry: Colligative Properties & Concentration Units
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Questions and Answers

What happens to the vapor pressure of a solution when a non-volatile solute is added?

  • It increases.
  • It decreases. (correct)
  • It remains the same.
  • It doubles.

    • Raoult's Law states that the vapor pressure of a solution is dependent on the nature of the solute.

    False

    What defines colligative properties?

    Colligative properties depend on the number of solute particles, not their nature.

    The relative lowering of vapor pressure of a solution is equal to the mole fraction of the ______.

    <p>solute</p> Signup and view all the answers

    Which of the following represents a colligative property?

    <p>Elevation of boiling point</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Mole Fraction = The ratio of the number of moles of one component to the total number of moles in the solution Relative Lowering of Vapor Pressure = The difference in vapor pressure between pure solvent and solution Ebullioscopy = The increase in boiling point due to the presence of a solute Cryoscopy = The decrease in freezing point due to solute addition</p> Signup and view all the answers

    A volatile solute will contribute to the total vapor pressure of a solution.

    <p>True</p> Signup and view all the answers

    What is the normality of a solution containing 0.248 moles of sulfuric acid dissolved in 250mL of solution?

    <p>0.496 N</p> Signup and view all the answers

    Molar solutions are more concentrated than molal solutions.

    <p>False</p> Signup and view all the answers

    What is the effect of adding a non-volatile solute on the escaping tendency of solvent molecules?

    <p>It decreases the escaping tendency of solvent molecules.</p> Signup and view all the answers

    What is the molality of a solution containing 18 g of urea in 1.5 kg of solvent?

    <p>0.04 molal</p> Signup and view all the answers

    The mole fraction is a __________ quantity because it is a ratio of two numbers representing moles.

    <p>dimensionless</p> Signup and view all the answers

    If 100g of sucrose is dissolved, how many grams of water are needed to prepare a 0.2 molal solution?

    <p>500g</p> Signup and view all the answers

    Raoult's law applies only to solutions containing volatile solutes.

    <p>False</p> Signup and view all the answers

    Calculate the mole fraction of water in a solution prepared by mixing 25g of water and 25g of ethanol.

    <p>0.5</p> Signup and view all the answers

    What is the definition of normality (N)?

    <p>Number of gram equivalents of solute dissolved in a liter of solution</p> Signup and view all the answers

    The molarity of a solution is calculated as the number of moles of solute per volume of solution in liters.

    <p>True</p> Signup and view all the answers

    Calculate the normality of a solution containing 1.5 g of calcium hydroxide dissolved in 850 mL.

    <p>0.035</p> Signup and view all the answers

    The equivalent weight of calcium is ______.

    <p>20</p> Signup and view all the answers

    Match the following concentration units with their definitions:

    <p>Normality (N) = Number of gram equivalents of solute per liter of solution Molarity (M) = Moles of solute per liter of solution Molality (m) = Moles of solute per kilogram of solvent Mole Fraction (χ) = Ratio of moles of solute to total moles of solution</p> Signup and view all the answers

    Which statement correctly describes the relationship between normality and molarity?

    <p>Molarity multiplied by molecular mass equals normality multiplied by equivalent weight.</p> Signup and view all the answers

    A dilute solution contains a higher concentration of solute than a concentrated solution.

    <p>False</p> Signup and view all the answers

    What is the mole fraction of solute if 2 moles of solute are dissolved in 8 moles of solvent?

    <p>0.2</p> Signup and view all the answers

    Study Notes

    Colligative Properties

    • Colligative properties depend on the number of solute particles, not their nature.
    • Key colligative properties include relative lowering of vapor pressure, elevation of boiling point, depression of freezing point, and osmotic pressure.

    Solution Concentration Units

    • Mole (n): The mass of a substance containing Avogadro's number (6.023 x 1023) of particles.
      • Mole (n) = (Weight in grams) / (Molecular mass)
    • Normality (N): Number of gram equivalents of solute per liter of solution.
      • Gram equivalent weight of element = (Atomic weight)/(Valency)
      • Gram equivalent weight of acid = (Molecular weight)/(Acidity)
      • Gram equivalent weight of base = (Molecular weight)/(Basicity)
      • Gram equivalent weight of salt= (Molecular weight)/(Total charge on cation or anion)
      • Normality (N) = (No. of gram equivalents of solute) / (Volume of solution in liters)
    • Molarity (M): Number of moles of solute per liter of solution.
      • Molarity (M) = (No. of moles of solute)/(Volume of solution in liters)
    • Molality (m): Number of moles of solute per kilogram of solvent.
      • Molality (m) = (No. of moles of solute) / (Mass of solvent in kg)
    • Mole Fraction (x): Ratio of moles of a component to the total moles of all components in a mixture.
      • Mole fraction (x) = (Number of moles of a component) / (Total number of moles of all components)

    Raoult's Law

    • The vapor pressure of a solution containing a non-volatile solute is directly proportional to the mole fraction of the solvent.
    • Psolution = Xsolvent × P°solvent
      • Psolution = vapor pressure of the solution
      • Xsolvent = mole fraction of the solvent
      • P°solvent = vapor pressure of the pure solvent

    Additional Notes

    • Concentration units that vary with temperature are molarity and normality.
    • Concentration units that are independent of temperature are molality and mole fraction.
    • The vapor pressure of a solution is the pressure exerted by the vapor in equilibrium with the liquid at a given temperature.
    • In a solution with a non-volatile solute, the vapor pressure is solely determined by the solvent.

    Questions (Examples)

    • Provided are example questions to calculate the normality, molarity, and molality of solutions.
    • Calculations involve finding equivalent weights, molecular weights, and mole fractions of various substances. Solutions may contain calcium hydroxide, sulphuric acid.

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    Colligative Properties PDF

    Description

    Explore the fascinating world of colligative properties and solution concentration units in this quiz. Understand how solute particles affect vapor pressure, boiling points, and freezing points, along with key concepts of mole, normality, and molarity. Test your knowledge and enhance your understanding of these essential chemical principles.

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