Question

A 14.8 Molar solution of NH₃ in water has a density of 0.90 g/mL. What is mole fraction of NH₃?

Answer 1

As we know that

molarity=( no of moles of solute / volume of solution in literature)

We have molarity 14.8 moles

We will assume that volume of solution is 1L for convenience.

So mass of NH_{​​​​​3} will be

14.8 × molar mass of NH3

= 14.8× 17.031 g/mol . ( Molar mass of NH3 is 17.031)

= 252.0588 g/mol mass of NH3

we have density of solution as 0.90g/ml

So the weight of 1L solvent is

1000 ml ×0.90g/ml

= 900 gram.

So weight of the water is

900-252.0588

=647.9412 gm

weigh of water is 647.9 gm

no of moles of water in 647.9 gm is

​​​647.9/18.02

= 35.95 moles

moles of water present is 35.95 moles

mole fraction= no of moles of solute/no of moles of solvent

= 14.08/35.95

=0.391

mole fraction of NH_{​​​​​3} is 0.391

i hope this helps if you have any questions or want more detailed explanation feel free to ask in the comment section below.

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