Density of 5.35 molarity H2SO4 is 1.22g m cm^-3. calculate the molality
Answers
7.690 mol kg^-1(approx.)
Given:
Density of the soln. = 1.22 g cm^-3
Molarity of the soln. = 5.35 M
To Calculate:
Molality of the soln.
Solving:
Let us assume the solution to be of 1 liter.
Molecular mass H2SO4
= 1 g x 2 + 23 g x 1 + 16 g x 4
= 2 + 23 + 64
= 98 g mol^-1
Formula for calculating the molarity of solution:
= No of moles of solute / Volume of solution in Liters
Calculating the number of moles in the solute:
Molarity of solution x Volume of solution in L
Substituting values into this formula we get:
= 5.35 x 1
= 5.35 mol
Calculating density of soln:
= 1.22 g cm^-3
= 1.22 g/mL
Converting into kg/L:
= 1.22 x 10^3 g/L
= 1.22 kg/L
Calculating the mass of solution:
= Density x Volume of soln.
Substituting the values into this formula we get:
= 1.22 kg/L x 1
= 1.22 kg
Calculating mass of solute H2SO4:
= Number of moles x Molecular Mass
= 5.35 x 98
= 524.3 grams
Converting into kilograms by dividing with 1000 we get:
= 0.5243 kg
Calculating the mass of solvent:
= 1.22 - 0.5243
= 0.6957 kg
Calculating the molality of solution:
= Number of moles of solute / Mass of solution in kg
Substituting the values into this formula we get:
= 5.35 mol / 0.6957 kg
= 7.690 mol kg^-1 (approx.)
Therefore, the molality of the solution is 7.690 mol kg^-1(approx.)