A solution is prepared by dissolving 10 g of urea in 90 g of water. Calculate the mole fraction of urea.

📘 Complete Step-by-Step Solution

📌 Given Data

Mass of urea = 10 g

Mass of water = 90 g

Molar mass of urea = 60 g mol⁻¹

Molar mass of H₂O = 18 g mol⁻¹

🔵 Step 1: Calculate Moles of Urea

Moles = Mass ÷ Molar Mass

Moles of urea = 10 ÷ 60

= 0.1667 mol

🟢 Step 2: Calculate Moles of Water

Moles of water = 90 ÷ 18

= 5 mol

🟠 Step 3: Calculate Total Moles

Total moles = Moles of urea + Moles of water

= 0.1667 + 5

= 5.1667 mol

🟣 Step 4: Calculate Mole Fraction of Urea

Mole fraction of urea is the ratio of moles of urea to the total moles of the solution.

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χ_urea = Moles of urea ÷ Total moles

= 0.1667 ÷ 5.1667

≈ 0.03226

🎬 3D-Style Mole Fraction Animation

Urea molecules are present in a larger number of water molecules.

Urea H₂O H₂O H₂O H₂O H₂O

Urea = 0.1667 mol
Water = 5 mol

Total = 5.1667 mol

✅ Final Answer

Mole fraction of urea ≈ 0.0323

🎯 Important Formula

χ_solute = Moles of solute ÷ Total moles of solution

χ_urea + χ_water = 1