Chemistry Class 12 NCERT Solutions: Chapter 2 Solutions Part 6

Q: 5. w/w solution of glucose in water means that of glucose in present in of the solution i.e., 10 g of glucose is present in of water.

Molar mass of glucose

Then, number of moles of glucose

∴ Molality of solution

Number of moles of water

Mole fraction of glucose

And, mole fraction of water

If the density of the solution is , then the volume of the solution can be given as:

∴ Molarity of the solution

Q: 6. How many mL are required to react completely with mixture of and containing equimolar amounts of both?

Ans:

Let the amount of in the mixture be x g.

Then, the amount of in the mixture is .

Molar mass of

∴ Number of moles

Molar mass of

∴ Number of moles of

According to the question,

Therefore, number of moles of

And, number of moles of

reacts with and according to the following equation.

1 mol of reacts with 2 mol of .

Therefore, mol of reacts with mol .

Similarly, 1 mol of reacts with 1 mol of .

Therefore, mol of reacts with mol of .

Total moles of required

is preset in 1000 mL of the solution.

Therefore, mol of is present in

of the solution

Hence, is required to react with mixture of and containing equimolar amounts of both.

Q: 7. A solution is obtained by mixing solution and solution by mass. Calculate the mass percentage of the resulting solution.

Answer:

Total amount of solute present in the mixture is given by,

Total amount of solution

Therefore, mass percentage of the solute in the resulting solution,

And, mass percentage of the solvent in the resulting solution,