Question

Calculate the mole fraction of urea and water if 2 g of urea is dissolved in 31.4 of aqueous solution

Answer 1

Explanation:

The correct chemical formula for urea is (NH2)2-CO.

Steps to solve the problem:

1) Convert g of urea to moles of urea using its molar mass.

2) Calculate mass of water in the solution by subtracting mass of urea from the mass of the solution.

3) Convert g of water to moles of water using its molar mass.

4) mole fraction of urea = moles of urea / (moles of urea + moles of water)

2 g urea x (1 mol urea / 60.06 g urea) = 0.033 mol urea

g of H2O = 31.8 - 2 = 29.8 g

moles of H2O = 29.8 g H2O x (1 mole H2O / 18.02 g H2O) = 1.65 mol H2O

mol fraction of urea = 0.033 / (0.033 + 1.65) = 0.020

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