Question

calculate the mass of one mole and one molecule of urea.(NH2CONH2)​

Answer 1

Explanation:

Calculate the mass of urea (NH 2CCONH2) required in making 2.5 kg of 0.2 molal aqueous solution.

0.2×2.5=0.625 moles of urea is required

no. of moles= Molarmass Mass

we know that,

no. of moles=0.625 moles

Molar mass of urea=14+2×1+12+16+14+2×1=60g/mol

∴ Mass= No. of moles× Molar mass =0.625×60

=37.5g

Answer 2

Answer:

The mass of one mole of urea is 60 g.

The mass of one molecule of urea is 1020 × 10²¹ g.

Explanation:

We have to calculate the mass of one mole and one molecule of urea.

We know that,

Molecular formula of urea = CH₄N₂O

Now,

Molar mass of urea = [ ( 1 × Atomic mass of carbon ) + ( 4 × Atomic mass of hydrogen ) + ( 2 × Atomic mass of nitrogen ) + ( 1 × Atomic mass of oxygen ) ]

⇒ Molar mass of urea = [ ( 1 × 12 ) + ( 4 × 1 ) + ( 2 × 14 ) + ( 1 × 16 ) ]

⇒ Molar mass of urea = ( 12 + 4 + 28 + 16 )

⇒ Molar mass of urea = 16 + 28 + 16

⇒ Molar mass of urea = 44 + 16

⇒ Molar mass of urea = 60 g mol¯¹

Now, we know that,

Number of moles of urea = ( Mass of urea ) / ( Molar mass of urea )

⇒ 1 mol = Mass of urea / 60 g mol¯¹

⇒ Mass of urea = 1 mol × 60 g mol¯¹

⇒ Mass of urea = 60 g

∴ The mass of one mole of urea is 60 g.

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Now, we know that,

Number of molecules = Number of moles × Avogadro's number

⇒ 1 = n × Nᴀ

⇒ 1 = n × 6.022 × 10²³

⇒ n = 1 ÷ 6.022 × 10²³

⇒ n = 0.166 × 10²³

⇒ n ≈ 0.17 × 10²³

⇒ n ≈ 17 × 10²¹ mol

Now, we know that,

Number of moles of urea = ( Mass of urea ) / ( Molar mass of urea )

⇒ 17 × 10²¹ mol = Mass of urea / 60 g mol¯¹

⇒ Mass of urea = 17 × 10²¹ mol × 60 g mol¯¹

⇒ Mass of urea = 17 × 60 × 10²¹ g

⇒ Mass of urea = 1020 × 10²¹ g

∴ The mass of one molecule of urea is 1020 × 10²¹ g.