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12 May, 20:26

A solution was prepared by dissolving 35.0 g of KCl in 225 g of water. a. Calculate the mass percent of KCl in the solution. Express your answer with the appropriate units. b. Calculate the mole fraction of the ionic species KCl in the solution. Express the concentration numerically as a mole fraction in decimal form. 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. d. Calculate the molality of KCl in the solution. Express your answer with the appropriate units.

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  1. 12 May, 20:38
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    1) mass % KCl = 13.5 %

    2) mol fraction KCl = 0.0362 = 3.6 * 10^-2

    3) Molarity KCl = 1.96 M

    4) Molality KCl = 2.08 molal

    Explanation:

    Step 1: Data given

    Mass of KCl = 35.0 grams

    Mass of water = 225 grams

    Molar mass of KCl = 74.55 g/mol

    Molar mass H2O = 18.02 g/mol

    Step 2: Total mass

    Total mass = mass KCl + mass H2O

    Total mass = 35.0 grams + 225.0 grams = 260.0 grams

    Step 3: Calculate mass % of KCl

    mass % KCl = (mass KCl / total mass) * 100%

    mass % KCl = (35.0 grams / 260.0 grams) * 100%

    mass % KCl = 13.5 %

    Step 4: Calculate moles KCl

    Moles KCl = mass KCl / molar mass

    Moles KCl = 35.0 grams / 74.55 g/mol

    Moles KCl = 0.469 moles

    Step 5: Calculate moles H2O

    Moles H2O = mass H2O / molar mass H2O

    Moles H2O = 225.0 grams / 18.02 g/mol

    Moles H2O = 12.49 moles

    Step 6: Calculate total moles

    Total moles = moles KCl + moles H2O

    Total moles = 0.469 + 12.49 = 12.959

    Step 7: Calculate mol fraction KCl

    mol fraction = 0.469 / 12.959 = 0.0362

    Step 8: Calculate molarity

    C = moles KCl / volume

    C = 0.469 moles / 0.239 L

    C = 1.96 M

    Step 9: Calculate molality KCl

    Molality = moles KCl / mass solvent

    Molality = 0.469 moles / 0.225 kg

    Molality = 2.08 molal
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