Use the References to access important values if needed for

Use the References to access important values if needed for this question. A solution of potassium chromate (K2CrO4) in water is 14.00 % potassium chromate by mass. Its density is 1.1163 g om at 20 °C. Compute its molarisy, mole fraction,and molality at tis impernture Molarity K2CrO 1.737 Mole fraction K2Cr04 Molality K2Cro 2.16 Submit Answer

Solution

1) Molarity

Molarity = No of moles of solute per Liter of solution

Mass of 1 Liter K2CrO4 solution = 1.1163g/ml × 1000ml = 1116.3g

Mass of K2CrO4 = (14.00/100)×1116.3g = 156.282g

Molar mass of K2CrO4 = 194.19g/mol

No of moles of K2CrO4 = 156.282g/194.19g/mol = 0.8048

Molarity of K2CrO4 =0.8048M

2) Mole fraction

Mole fraction = No of moles of solute /(No of moles of solute + No of moles of solvent)

Mass of 1 Liter solution of K2CrO4 = 1116.3g

Mass of water = 156.282g

Mass of water = 1116.3g - 156.282g = 960.018g

No of moles of Water = 960.018g/18.02g/mol = 53.275

No of moles of K2CrO4 = 0.8048

Total no of moles = 53.275 + 0.8048 = 54.0798

Mole fraction of K2CrO4 = No of moles of K2CrO4/Total moles

  Mole fraction of K2CrO4 = 0.8048/54.0798

Mole fraction of K2CrO4 = 0.0149

3) molality

Molality = No of moles of solute per 1kg of solvent

Mass of water in 1L of solution = 960.018

No of moles in 1L of solution = 0.8048

Molality of K2CrO4 = (0.8048mol/960.018g)×1000g) =0.8383m