Question

What is the mole fraction of urea, CO(NH2)2, in a solution prepared by dissolving 4.0 g of urea in 32.0 g of methanol, CH3OH

Answer 1

0.0630

Step-by-step explanation:

The molar mass of urea = 60 g/mol

we all know that:

`\mathtt{number \ of \ moles = (mass )/(molar \ mass)}`

Then; the number of moles of urea

=
`\mathtt{(4.0 \ g)/(60 \ g/mol)}`

= 0.0667 mol

Similarly; the number of moles of methanol

=
`\mathtt{(32 \ g)/(32.04 \ g/mol)}`

= 0.9988 mol

The total number of moles = (0.0667 + 0.9988) mol

= 1.0655 mol

Finally,the mole fraction of urea
`\mathtt{(X_(urea))}` =
`\mathtt{( n_(urea))/((n_(urea)+n_(methanol)))}`

`\mathtt{(X_(urea))}` =
`\mathtt{(0.0667 \ mole)/(1.0655 \ mole)}`

= 0.0630