Answer:
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