Two beakers, one with pure water (blue) and the other with a solution of NaCl in water (green), are placed in a closed container as represented by drawing (a). Which of the draw- ings (b)–(d) represents what the beakers will look like after a substantial amount of time has passed?

Video transcript

Hello. In this problem, we are told that two beakers are enclosed in a container. As illustrated below. One beaker contains pure water which is shown in blue and the other contains an Aquarius potassium chloride solution and that is shown in pink. So let's consider first what is happening with the water beaker. So some of the water molecules will have sufficient energy to enter the vapor phase. Some of these molecules then will lose energy and return to the liquid phase when the rate of vaporization is equal to the rate of condensation and an equilibrium. Established the pressure of the water vapor above the liquid is called the vapor pressure of the liquid. With the potassium chloride solution, potassium chloride is a non volatile salute. Some of the potassium chloride will be at the surface which will hinder the ability of the water to enter the vapor phase. And so the presence of potassium chloride will lower the vapor pressure. So we will have a higher vapor pressure here and lower vapor pressure above the potassium chloride solution. The rate in which the water molecules condense or return to the liquid phase will be the same on both the water and the potassium Floyd side. So since the water will vaporize at a faster rate over the water than it will over the potassium chloride solution we will get a net movement. I'm getting a transfer of water from the beaker that contains pure water to the beaker that contains the potassium chloride solution. So that means then over a period of time the amount of pure water will decrease and the amount of potassium chloride solution will increase, And so that then leads us to answer. C. I hope you found this to be helpful. Thanks for watching.