1st year Chemistry Chapter 6 Chemical Equilibrium Question an Answers
Short and Simple Question an Answer
Q.1: Justify that chemical equilibrium is dynamic in nature?
Ans: In reversible chemical reactions the molecules of reactions collide and convert into products. At the same time the molecules of the products are converted into reactants. When two opposing forces maintain the equal, rates then equilibrium is there and that is dynamic equilibrium in nature.
Q.2: When does four types of chemical equilibrium constants for a reaction become equal?
Ans: When we have such a reversible reaction, in which the total number of moles of reactants and products are equal then Kp = Kc = Kn. In order words An = 0, where An is the difference of number of moles of reactants and products.
Q.3: The change of temperature disturbs the equilibrium position and the equilibrium constant of reaction? Justify?
Ans: All the reversible reactions are disturbed by changing their equilibrium position and equilibrium constant by disturbing the temperature. Actually change of temperature changes the energy contents of reactants and products.
Q.4: Why is solubility of cose in water is increased by increasing the temperature?
Ans: The solubility of glucose in water is an endothermic process. Increase of temperature pushed the system to that side where heat is absorbed, and that is the side where solubility increases.
Q.5: What the nature of solution having PH = 7.5?
Ans: The solution with PH 7 is neutral and having values more than 7 have greater concentration of OH and less concentration of H*, so the solution is basic.
Q.6: What is buffer capacity?
Ans: Buffer capacity is a ability of a buffer to resist the change of PH, when a few drops of an acid and base is added from outside. The best buffer is obtained. (i) when PH of the buffer is equal to Pka of the acid and the concentration of the salt and acid are equal. (ii) The OH of the buffer is equal to Pkb or the base.
Q.7: Why do we need buffer solution?
Ans: Buffer solutions are used in many industrial processes as electroplating manufacture of leather, preparation of dyes and manufacture of photographic materials. Buffer solutions are used by analytical chemists and to calibrates PH meter. They are also in culture media.
Q.8: How does a catalyst affect a reversible reaction?
Ans: A catalyst affects the rates of both steps equally, so the equilibrium position remains the same. It means that equilibrium constant should be the same. Actually a catalyst decreases the energy of activation of the chemical reaction by giving a new path to the reaction. In this way, a greater % age of reactant molecules is able to cross the energy barrier and the rate of reaction increases.
Q.9: What is meant by stage of chemical equilibrium?
Ans: In reversible chemical reactions two opposing reactions occur. A stage reaches for the reaction when the rates of two opposing reactions are equal. This stage is called stage of chemical reaction.
Q.10: Why the rates of chemical reaction is depend upon the concentrations of reactants?
Ans: This is according to the law of mass action. The rates of chemical reactions are directly proportional to the product to the active masses of reactants. Greater the number of molecules, greater the collisions and greater the rate.
Q.11: Why is the equilibrium blished? Only the reaction vessel is closed for a gaseous reaction?
Ans: If some of the products or the reactants in the open vessel leave the vessel during the progress of the reaction then the stage of equal rates in distributes and equilibrium can not be established. In such situation the reaction is pushed to the toward direct ion or backward direction.
Q.12: The change of volume disturbs the equilibrium position for some of the gaseous phase reactions but not the equilibrium constant. Why?
Ans: Those gaseous phase reversible reactions, which happens with changing number of moles are affected by the change of volume at equilibrium stage. Their equilibrium position is disturbed, but equilibrium is not changed.
Q.13: What is the effect of rise in temperature on the stability of Kl in water?
Ans: The heat of solution of KI in water in positive. It means it is an endothermic process. When the temperature is increased, it will absorb more heat and more dissolution will take place.
Q.14: What is buffer solution?
Ans: A solution which resists the change of PH, when a small amount of an acid or a base is added in that. Buffer are prepared by mixing two components. Weak acid + salt with a strong base. Weak base + salt with a strong acid.
Q.15: Define the effect of common ion solubility? Give examples?
Ans: According to the Le Chatelier’s principle, if a common ion is added in a solution, then the solubility of the electrolyte decreases and the solute is completed to settle down. If Cl are added in saturated solution of NaCl, then NaCl settles down, because its solubility decreases.