Answer:
Mol fraction H2O = 0.99991
Mol fraction KBr = 0.00009
mass % KBr = 0.059 %
mass % H2O = 99.941 %
Explanation:
Step 1: Data given
Mass of KBr = 0.21 grams
Molar mass KBr = 119 g/mol
Volume of water = 355 mL
Density of water = 1.00 g/mL
Molar mass water = 18.02 g/mol
Step 2: Calculate mass water
Mass water = 355 mL * 1g /mL
Mass water = 355 grams
Step 3: Calculate moles water
Moles water = mass water / molar mass water
Moles water = 355 grams / 18.02 g/mol
Moles water = 19.7 moles
Step 4: Calculate moles KBr
Moles KBr = 0.21 grams / 119 g/mol
Moles KBr = 0.00176 moles
Step 5: Calculate total moles
Total moles = 19.7 moles + 0.00176 moles
Total moles = 19.70176 moles
Step 6: Calculate mol fraction
Mol fraction H2O = 19.7 moles / 19.70176 moles
Mol fraction H2O = 0.99991
Step 7: Calculate mol fraction KBr
Mol fraction KBr = 0.00176 / 19.70176
Mol fraction KBr = 0.00009
Step 6: Calculate mass %
mass % KBR = (0.21 grams / (0.21 + 355) grams) *100%
mass % KBr = 0.059 %
mass % H2O = (355 grams / 355.21 grams) *100%
mass % H2O = 99.941 %
