Question

calculate the mass of urea required in making 2.5kg of 0.25 molal aqueous solution​.
Please answer properly

Answer 1

Answer : The mass of urea in the solution is, 37.5 grams

Solution : Given,

Molality of solution = 0.25 molal

Molar mass of urea = 60 g/mole

Mass of solvent = 2.5 Kg

Molality : It is defined as the number of moles of solute present in one kilogram mass of solvent.

Formula used :

$Molality=\frac{\text{Mass of urea}}{\text{Molar mass of urea}\times \text{Mass of solvent in Kg}}$

Now put all the given values in this formula, we get the mass of urea.

$0.25mole/Kg=\frac{\text{Mass of urea}}{60g/mole\times 2.5Kg}$

$\text{Mass of urea}=37.5g$

Therefore, the mass of urea in the solution is, 37.5 grams

Answer 2

_/\_Hello mate__here is your answer--

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Molar mass of urea (NH2CONH2)

= 2(1 × 14 + 2 × 1) + 1 × 12 + 1 × 16

= 60 g mol^−1

0.25 molar aqueous solution of urea means:

1000 g of water contains 0.25 mol

= (0.25 × 60)g of urea

= 15 g of urea

That is,

(1000 + 15) g of solution contains 15 g of urea

Therefore, 2.5 kg (2500 g) of solution contains

= (15× 2500)/( 1000+ 15 )

=36.95 g

= 37 g of urea (approximately)

Hence, mass of urea required = 37 g

I hope, this will help you.☺

Thank you______❤

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