Question

if 4 g of Noah dissolve in 36 g of h20 calculate mole fraction of each component in the solution. also determine molarity of solution ​

Answer 1

Solution :-

4 g of mass in NaOH = 0.1 mole of NaOH or (4/40 moles)

36 g of mass in = 2 moles of H_2O or (36/18 moles)

Here, NaOH is the solute and is the solvent

Formula: 1  

Using the formula for mole fraction:

Mole fraction of = No of moles in /Total no of moles (+NaOH)

Total no of moles = 2 + 0.1 = 2.1

Mole fraction of = 2/2.1 = 0.952

Formula: 2  

Using the formula for water:

Mole fraction of NaOH = No of moles of NaOH/Total no of moles  

Mole fraction of NaOH = 0.1/2.1 = 0.048

Mass of solution = Mass of + Mass of NaOH  

= 36 + 4  = 40 g

Volume of solution = Mass of solution/Density of solution  

= 40/1 = 40 mL

Molarity of the solution = No of moles of NaOH/Volume of solution L  

= 0.1/0.04 L = 2.5 m

Answer 2

Answer:

a). Mole fraction of each component

4 g of NaOH = 4/40 mole or 0.1 mole of NaOH

36 g of water = 36/18 mole or 2 moles of H2O

Here, NaOH is the solute and H2O is the solvent

Using the formula for mole fraction :

X = mole of solute/(mole of solute + mole of solvent)

XNaOH=0.1mole/(0.1mole+0.2mole)

XNaOH=0.1mole/0.3mole

XNaOH=1/3

So, mole fraction of NaOH = 1/3

Similar formula applies for water, in which,

XH2O=0.2mole/(0.1mole+0.2mole)

XH2O=0.2mole/0.3mole

XH2O=2/3

Thus, mole fraction of water (H2O) is 2/3

b). Molarity of the solution

As mentioned above, the amount of NaOH = 4 g and water = 36 g, then the total amount of components = 40 g. Assuming the density of the solution is 1, thus the volume of the solution = 40 mL.

As stated, mole of the solute (NaOH) = 0.1 mole, hence the molarity of the solution being : 0.1 mole/40 mL solution. Since the molarity is expressed as mole of solute/1 L solution, then the molarity of solution = 1000/40 x 0.1 mole = 2.5 M.

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