Question

Calculate the molality of 20 M H2SO4 given that the solution has density of 2.65 g/ml.​

Answer 1

Answer:

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>>Molarity of H2 SO4 (density 1.8 g / mL)

Question

Molarity of H

2

SO

4

(density 1.8 g / mL) is 18 M. The molality of this H

2

SO

4

solution is:

A

36

B

200

C

500

D

18

Medium

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Correct option is C)

Given : Molarity of H

2

SO

4

= 18M

As, Molarity =

volume of solution

no. of moles of solute

i.e., 18moles of sulphuric acid is present per litre of solution.

Density=1.8g/mL {given}

Thus , mass of one litre of this solution ,

Density =

volume

mass

mass = density×volume

mass = 1.8×1000

mass = 1800g

Thus , mass of 1litre 18M H

2

SO

4

solution is 1800g or 1.8kg.

Now, mass of solution = mass of solute + mass of solvent

mass of solution = no. of moles of solute X molar mass of solute + mass of solvent

1800 = 18×98 + mass of solvent

mass of solvent = (1800−1764)g

mass of solvent = 36g

Now , molality of H

2

SO

4

solution is given by,

molality =

massofsolvent(inkg)

numberofmolesofsolute

molality =

36

18×100

molality = 500m

Hence, the molality of H

2

SO

4

solution is 500m.