Please , I need full explanation and full answers . The enthalpy of solution of
ID: 1023948 • Letter: P
Question
Please , I need full explanation and full answers .
The enthalpy of solution of KBr in water is about +198 kJ/mol (endothermic). Nevertheless, the solubility of KBr is relatively high. Explain why. A sample consisting of various gases contains 3.5*10^-6 mole fraction of radon. This gas at a total pressure of 36 atm is shaken with water at 30 degree C. Assume that the solubility of radon in water with 1 atm pressure of the gas over the solution at 30 degree C is 7.27*10^-3M. Calculate the molar concentration of radon in the water. Caffeine (C_8H_10N_4O_2) is a stimulant found in coffee and tea. A solution of caffeine in the solvent chloroform (CHCI_3) has a concentration of 0.0520m. a) Calculate the percentage of caffeine by mass in the solution. b) Calculate the mole fraction of caffeine in the solution.Explanation / Answer
Problem-2: Given that when the atmospheric pressure is 1 atm, the concentration of radon in water is 7.27x10-3 M
Now applying Henry's law
P = KH x C
=> KH = P / C = 1 atm / 7.27x10-3 M = 137.6 atm / M
Now when P = 36 atm, the molar concentration of radon in water can be calculated as
P = KH x C
=> C = P /KH = 36 atm / 137.6 atm / M = 0.262 M (answer)
Problem-3:(a): Given molality of the solution, m = 0.0520 m
i.e 0.0520 mol of caffeine is present in 1000 g of solvent chloroform.
molar mass of caffeine = 194.19 g/mol
Hence mass of caffeine present in 1000 g of solvent chloroform = 0.0520 mol x 194.19 g/mol = 10.098 g
Hence percentage of caffaine by mass in the solution = [10.098 g / 1000 g] x 100 = 1.01 % (answer)
(b): molar mass of chloroform = 119.3776 g/mol
mass of chloroform = 1000 g
Hence moles of solvent chloroform = mass / molar mass = 1000 g / 119.3776 g/mol = 8.377 mol
mole fraction caffeine in the solution = moles of caffeine / (moles of caffeine + moles of chloroform)
= 0.0520 mol / (0.0520 mol + 8.377 mol)
= 0.00617 (answer)