Two beakers, 1 and 2, containing 50 mL of 0.10 M urea and 50...

Two beakers, 1 and 2, containing 50 mL of $0.10 M$ urea and 50 mL of $0.20 M urea, respectively, are placed under a tightly sealed container (see Figure 12.12) at 298 K . Calculate the mole fraction of urea in the solutions at equilibrium. Assume ideal behavior.

Transcript

00:01 In this question we want to determine the mole fraction at equilibrium so if we are to look at the more fraction let's call this x the more fraction of say urea this is the number of moals of urea divided by the total number of more and t and this time around the total is going to be the number of moles of urea plus the number of moles of h2 o so the more fraction of this is going to be the number of moles divided by nu plus h2o so what we have we have the initial number of moles and then we have an equilibrium this first of all look at a situation where we are under initial conditions before equilibrium is attained so the number of moles of urea in the first pica this is going to be 0 .1 divided by 1 that is 0 .1 moral per liter multiplied by the concentration which is 0 .05 and this is equal to 0 .05 moles and the number of moles of urea and the second pika this is 0 .2 multiplied by 0 .05 which is equal to 0 .01 moles this is coming from number of moles is equal to volume multiplied by the concentration of the solution.

01:25 Now looking at h2 of the number of moles of h2o in each pika, this is going to be equal to 50 mils divided by 1 8 .02.

01:42 That is what we have here, this is 50 mils multiply by 1 mil, 1 gram p mil litre.

01:48 We are using mass is equal to volume times density.

01:54 So the number of moles is equal to mass divided by the molar mass.

01:59 This mass we are calculating from the product of the mass of the volume and the density.

02:04 So we're going to have h2o being equal to 8 point rather 2 .8 more.

02:11 Therefore the molar mass or rather the mass fraction of urea in the first pica, this is going to be equal to 0 .005 divided by 0 .005 plus 0 .01...

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