Calculate the molality and mole fraction of water, respectively, of a solution that is made by dissolving 3.50 g of potassium nitrate in 50.0 g of water. the final volume of the solution is 56.0 ml.

Answer : The molality of the solution is 0.692m. The mole fraction of water is 0.988.

Explanation :

Molality :

The molality of a solution is calculated as,

Step 1 : Find moles of Potassium Nitrate KNO₃.

Molar mass of KNO₃ is 101.1 g/mol

Mass of KNO₃ is 3.50 g

Step 2 : Find kg of the solvent

Water is solvent here.

Mass of water = 50.0 g = 0.050 kg

Step 3 : Use molality formula

Let us use these values to find molality of the solution.

The molality of the solution is 0.692 m

Mole fraction :

The mole fraction of a component of a mixture is calculated as,

Step 1 : Find moles of water

Let us find moles of water using the mole formula

Molar mass of water is 18.02 g/mol

Step 2 : Use mole fraction formula

Mole fraction of H₂O =

Mole fraction of H₂O is 0.988

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.