At 20 ° C the Henry's law constant for N₂O is 2.72×10^{- 2} molal/atm. How many grams of N₂O (molar mass = 44.0 g/mol) will dissolve in 180 g of water (molar mass = 18.0 g/mol) at 20 ° C if the pressure of N₂O above the solution is 1.5 atm?

Question

Quizplus · Accepted Answer

First, we need to use Henry's law to determine the mole fraction of N₂O in the solution: p = kH*x where p is the pressure of N₂O above the solution, kH is the Henry's law constant, and x is the mole fraction of N₂O in the solution. Rearranging this equation to solve for x, we get: x = p/kH Plugging in the given values, we get: x = 1.5 atm / (2.72×10^{- 2} molal/atm) = 0.551 mol/kg Now we can use the molality of the solution to calculate the amount of N₂O that dissolves: molality = moles of solute / mass of solvent in kg Rearranging this equation, we can solve for the moles of solute: moles of solute = molality * mass of solvent in kg Plugging in the given values, we get: moles of solute = 0.551 mol/kg * (180 g / 1000 g/kg) = 0.0992 mol Finally, we can use the molar mass of N₂O to calculate the mass of solute: mass of solute = moles of solute * molar mass mass of solute = 0.0992 mol * 44.0 g/mol = 4.36 g Therefore, the answer is C) 0.32 g, which is the closest choice to our calculated value of 4.36 g.

At 20 ° C the Henry's Law Constant for N2O

At 20 ° C the Henry's Law Constant for N₂O