Question 2 Which solution will have the lowest boiling...

Question 2 Which solution will have the lowest boiling point? 10 g of potassium sulfate in 100 mL of water 10 g of sodium acetate in 100 mL of water 10 g of hydrogen iodide in 100 mL of water 100 mL of pure water Question 3 Which solution will have the highest boiling point? 10 g of sodium acetate in 100 mL of water 100 mL of pure water 10 g of potassium sulfate in 100 mL of water 10 g of hydrogen iodide in 100 mL of water

Transcript

00:01 Hello students, this question consists of multiple part.

00:03 In the first part, the mass of the potassium sulphide and its volume and the density of the solution has been given.

00:10 We have to find out the molality.

00:12 First of all, we are going to calculate the mass of the solution which is given by density into volume.

00:17 Volume is 1000 ml and density is 1.

00:20 On multiplying this, it will be equal to 100 gm.

00:23 And now we are going to calculate the number of moles of potassium sulphide which is given by mass divided by molar mass of potassium sulphide is 174 .26.

00:33 On multiplying these two, we will get 0 .0862 moles.

00:39 And coming to the next, we are going to find out the molality.

00:43 Molality is given by number of moles of the solute divided by the mass of the solution in kg.

00:50 We are converting this into kg.

00:51 Dividing by 1000, it will become 0 .1 kg.

00:55 Substituting the value 0 .1, on solving this, we will get the molality of the solution will be equal to 0 .862.

01:02 This corresponds to option d.

01:04 Coming to the second part of the question, the mass of the sodium nitrate has been given and its volume of the water and its density and vapor pressure has been given.

01:15 We have to find out the vapor pressure of the solution.

01:17 First of all, we are going to calculate the number of moles of sodium nitrate which is given by mass divided by molar mass of sodium nitrate which is equal to 85.

01:26 Then the number of moles will be equal to 0 .206 moles.

01:31 Coming to the calculation of mass of the water which is given by density into volume, this will be equal to 50 g.

01:38 The number of moles of water will be given by mass divided by molar mass of water.

01:44 On dividing this, we will get the number of moles of water will be equal to 2 .778 moles.

01:52 And coming to the calculation of the mole fraction of the solvent, the number of moles of water is given by 2 .778 divided by 2 .778 plus number of moles of the sodium nitrate will be equal to 0 .206.

02:09 On solving this, we will get the mole fraction of the water that is the solvent will be equal to 0 .931.

02:19 Using this and applying the raoult's law, we are going to calculate the vapor pressure of the solution...

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