Question

calculate molality of 2M urea solution having density 1.25gmL. (molar mass of urea is 60g/mol​

Answer 1

Answer:

in this question 1M solution of NaNO

3

,

By definition if Molarity we know that it is the no. of moles present in per litre of solution. = 1M molar solution has 1 mole of NaNO

3

for 1000ml of solution.

Therefore, mass of solute is mass of 1 mole of NaNO

3

= 23+14+48 = 85 gm.

volume of solution = 1000 ml as per definition.

Now,Given that density is 1.25 g/cm3

Therefore, mass = 1.25×1000 (m = density X volume)

=> mass = 1250 gm (solution mass)

Mass of solvent = mass of solution - mass of solute

= 1250 - 85= 1165gm.

Molarity is the no. of mole of solute per kg of solvent

=> m =

1165

1

×1000 =

1165

1000

=0.85m