12.522 grams of KOH is dissolved in enough water to make 475 mL of solution. Find the molarity, Molality, Mole Fraction and w/w%
Dear student
Mass of KOH = 12.522g
Volume = 475mL =0.475L
Molarity = no.of moles of solute/ Volume of solution in L
nO.of moles of KOH = mass of KOH given/ molar mass of KOH
= 12.522g/56.1056g/mol
=0.223 mol
now Molarity = 0.223 mol/0.475L
= 0.47M
Molality = Molality = no. of moles / mass of solvent in Kg
Now, the density of water is 1g/mL
Density = mass/volume
mass of solution = 1g/mL x 475mL
=475g
Now, molality = 0.223/ 0.475
= 0.47m
That is 0,47moles dissolved in 1000kg water
Moles of water = weight of water/molecular weight of water
= 18/1000
=55.55mol
no.of moles = weight of water/molar mass
55.55 = weight of water/ 18
Mole fraction = no.of moles of solute/ no.of moles of solute + no.of moles of solvent
= 0.47/0.47 + 55.55
= 0.0085
Total Mass of solution = Mass of solute + Mass of solvent
weight(w/w) % = mass of component / total mass of solution x 100
= 12.522/ 12.522 + 475 x 100
= 2.57%
Regards
Mass of KOH = 12.522g
Volume = 475mL =0.475L
Molarity = no.of moles of solute/ Volume of solution in L
nO.of moles of KOH = mass of KOH given/ molar mass of KOH
= 12.522g/56.1056g/mol
=0.223 mol
now Molarity = 0.223 mol/0.475L
= 0.47M
Molality = Molality = no. of moles / mass of solvent in Kg
Now, the density of water is 1g/mL
Density = mass/volume
mass of solution = 1g/mL x 475mL
=475g
Now, molality = 0.223/ 0.475
= 0.47m
That is 0,47moles dissolved in 1000kg water
Moles of water = weight of water/molecular weight of water
= 18/1000
=55.55mol
no.of moles = weight of water/molar mass
55.55 = weight of water/ 18
Mole fraction = no.of moles of solute/ no.of moles of solute + no.of moles of solvent
= 0.47/0.47 + 55.55
= 0.0085
Total Mass of solution = Mass of solute + Mass of solvent
weight(w/w) % = mass of component / total mass of solution x 100
= 12.522/ 12.522 + 475 x 100
= 2.57%
Regards