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

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.