100g solution of urea in water has 40g urea molar mass 60g/mol .what is molarity of urea solution ?what is mole fraction of urea in solution?
Answers
Explanation:
Step 1 : Find moles of solute.
The solute in this case is urea. Let us find moles of urea.
Molar mass of urea is 60.1 g/mol
We have 10 grams of urea.
Let us plug in these values to find moles.
We have 0.166 mol urea.
Step 2 : Find mass of solvent
Water is solvent here .
The mass of solution is given as 100 g.
Mass of solution = mass of solute + mass of solvent
100 g = 10 g + mass of solvent
mass of solvent = 100 g - 10 g = 90 g = 0.09 kg
Step 3 : Use molality formula
The molality of a solution is calculated using following formula
The molality of the given solution is 1.84 m
Molality of urea solution is 11.11 m and mole fraction of urea in solution is 0.1675.
Given,
- mass of solution= 100 g
- mass of urea = 40 g
- molar mass of urea = 60 g/ mol
Calculation:
moles of urea= mass of urea in a solution / molar mass of urea
= 40/60
= 0.67 moles
mass of solvent = mass of solution - mass of solute
= 100- 40
= 60 g
moles of solvent ( water) = mass / molar mass
= 60 / 18. = 3.33
total moles = 0.67+ 3.33 = 4
Molality= moles / kg solvent
= 0.67× 1000/ 60
= 11.11 m
Mole fraction of urea = moles of urea/ total moles of solution
= 0.67/4
= 0.1675
Hence,Molality of urea solution is found to be 11.11 m and mole fraction of urea in solution is 0.1675.
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