Ncert Solutions Chemistry Class 12th

Given-

Mass of K₂SO₄, w = 25 mg = 25 X 10^-3 g,

Molar mass of K₂SO₄ = (39*2) + (32*1) + (16*4) = 174 g mol^-1

Volume V = 2 liter

T = 25⁰C + 273 = 298 K (add 273 to convert in Kelvin)

The reaction of dissociation of K₂SO₄ is written as,

K₂SO₄ → 2K ⁺ + SO₄^2-

Number if ions produced = 2 + 1 = 3, hence vant Hoff's factor, I = 3

Here, we use vant Hoff's equation for dilute solutions, given as,

^{πV = inRT}

where, n is the number of moles of solute, R is solution constant which is equal to the gas constant (0.082) and T is the absolute temperature (298 K).

Hence, the osmotic pressure of a solution is 5.27x10^-3atm

16.24

Alitame is a high potency artificial sweetener and it is not possible to control the sweetness imparted to food by alitame. Alitame is an artificial sweetener that is 2,000 times as sweet as sugar. This sweetness is very high as compared to the natural sugar and use of such sweetener is very critical while preparing sweet dishes. The structure of alitame is as follows:

Hence problem arises when alitame is used for sweetening purposes.

Given-

Vant Hoff's factor, I = 2.47

osmotic pressure, π = 0.75 atm

Volume of solution = 2.5L.

To determine the amount of CaCl₂, we use vant Hoff's equation for dilute solutions, given as,

πV = inRT

where, n is the number of moles of solute, R is solution constant which is equal to the gas constant and T is the absolute temperature.

Hence, the amount of CaCl₂ dissolved is 3.425g

Given-

K_H for O₂ = 3.30 * 10⁷ mm Hg,

K_H for N₂ = 6.51 * 10⁷ mm Hg

Percentage of oxygen (O₂) = 20 %

Percentage of nitrogen (N₂) = 79%

Total pressure = 10 atm

Using Henry's law,

where, p is the partial pressure of gas in the solution and K_H is Henry's constant.

Thus, the mole fraction of oxygen in solution, x_oxy = 4.61x10^-5

and the mole fraction of nitrogen in solution, x_nit is 9.22x10^-5

16.23 

Artificial sweetening agents like Saccharin, Alitame, Sucrolose can be used in the preparation of sweets for a diabetic patient as they do not add any calories to the body.

Diabetic people are advised to consume low-calorie diet [fewer carbohydrates & more proteinaceous and fiber rich]. The refined sugar like sucrose adds calorie to the diet but complex sugar and starches do not add to the calorie intake of a person and at the same time impart a sweet taste to diet. Artificial sweeteners are generally either complex sugar or protein in nature

Given-

Thus, mole fraction of benzene in vapour phase is 0.6744

16.22 

Artificial sweetening agents refer to those compounds which impart sweet taste to any food product but at the same, they do not add any calories to the body. Example: Aspartame, Alitame, Saccharin etc.

The P_total for the values given in the graph is found out and plotted in the graph.

It can be observed from the graph that the plot for the p total of the solution curves downwards. Therefore, the solution shows negative deviation from the ideal behaviour.

16.21 

At elevated temperatures, aspartame is unstable and break down to give a tasteless compound because of which aspartame is limited to cold foods and drinks.

Aspartame is methyl ester of the dipeptide obtained from phenylalanine and aspartic acid. It is about 180 times as sweet as cane sugar. The structure of aspartame is as follows: