Question

Calculate the mass of urea required in making 2.5kg of 0.25 molalaqueous solution

Answer 1

Hey !!

Mass of required aqueous solution = 2.5 kg = 2500 g

0.25 molal aqueous solution of urea it means that 0.25 mole of urea is dissolved in 1000 grams of water.

Mass of water = 1000 g

Mass of urea = 0.25 mol

Molar mass of urea (H₂NCONH₂) = 4 × 1 + 2 × 14 + 1 × 12 + 1 × 16 = 60 g mol⁻¹

        NOTE :- Mass of urea = Number of moles of urea × Molar mass of urea

     Mass of 0.25 moles of urea = 0.25 mol ×× 60 h mol⁻¹ = 15 g

Mass of solution = 1000 g + 15 g = 1015 g

1015 g of aqueous solution contains urea = 15 g

∴ 2500 g of aqueous solution will require urea

         = 15 g / 1015 kg × 2500 g

            = 36.95 g

HOPE IT HELPS YOU !!

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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