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Why do gases always tend to be less soluble in liquids as the temperature is raised?

Answer:

When gas dissolve in liquid it generate a small quantity of heat so we can say that dissolution of gas in a liquid is a exothermic reaction.
Gas + liquid  < --- >  solution  + heat

According to le Chatelier's principle when we increase the temperature in a exothermic reaction , the reaction will move to back ward direction that means solution will dissociate and will give gas .Hence with the rise of temperature gas will less soluble.


For most of gases like N2, O2, He etc. the value of Henry's constant, KH increases with temperature and as a result of this solubility of gases decreases with increase of temperature. We know, at given temperature.
Partial pressure of gas in solution = KH x mole fraction of gas in sol. KH depends on the nature of gas. For example, KH value of O2 at 293 K is 34.86 while at 393 K it is 46.82 kilo bar.

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Define the following terms:
Mass percentage.

Answer:

Mass percentage: It is the amount of solute in grams dissolved per 100 g of solution, e.g., 5% solution sodium carbonate mass 5 g of solid sodium carbonate is present in 100 g of solution.

Mass% = Moles of soluteMass of solution×100
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What role does the molecular interaction play in solution of alcohol and water?

Answer:


In both the components, water (A component) and alcohol (B component), the molecules are hydrogen bonded, i.e., A-A as well as B-B interactions are mainly H-bonds forces. When these two components are mixed to form the solution, due to molecular collisions A-A and B-B interactions are broken down and new interactions of the type A-B are formed. A-B interactions are also mainly H-bonds i.e., the molecules of one liquid will tend to break the hydrogen bonds in the molecules of other liquid and vice-versa. A-B interactions formed will be weaker than A-A and B-B types of of interactions as the alcohol and water solution show positive deviation and it will lead to increase in volume (ΔVmix is + ve).

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Concentrated nitric acid used in the laboratory work is 68% nitric acid by mass in aqueous solution. What should be molarity of such sample of the acid if the density of solution is 1.504 g mL–1?

Answer: 

68% by mass implies that 68 g of HNO
are present in 100 g of solution.
Volume of solution = Mass of solutionDensity of solution

                             = 100g1.504 g mL-1= 66.5 cm3 = 0.665 L.
Molar mass,
        MB of NHO3 = 1+14+48 = 63.
           Molarity = ωAMB×V               = 68 g63 g mol-1 × 0.0665               = 16.23 M.
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Define the following terms:
Molarity


Answer:

Molarity: The concentration expressed as the moles of solute per litre of solution is the molarity. It is denoted by M.

Molarity = Mass of soluteLitres of solution=nBV

A solution of one molar concentration is represented by 1 M, a two molar solution by 2 M and a one tenth molar solar solution is represented by 0.1 M.

 
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