CBSE Class 11 Chemistry - Chemical Equilibrium. Students are advised to refer to the attached assignments and practice them regularly. This will help them to identify their weak areas and will help them to score better in examination. Parents should download and give the assignments to their children for practice.
CHEMICAL EQUILIBRIUM ONE MARK QUESTIONS
1 What happens to the concentration of products when the pressure is increased in the following reaction at equilibrium? 2NO2(g)⇌ N2O4(g)?
2 Name an acid buffer and an alkaline buffer each.
3 Copper is precipitated as sulphide in the II group while Zn is precipitated as sulphide in the IV group. Explain.
4. Write the formula for the conjugate acid of (i) F- (ii) OH-
5. Write the formula for the conjugate base of ( i) HNO2 , (ii) OH-
TWO MARKS QUESTIONS
1. Give reason:
a) Equilibrium can be established only in closed system.
b) Chemical equilibrium is dynamic in nature.
2. An equilibrium mixture contains [PCl5] = 0.15 ; [PCl3] = 0.29 ; [Cl2] = 0.32. If Kc for the dissociation of PCl5 at the same temperature is 3.5, in which direction is the reaction proceeding?
3. Differentiate between
a) hydrolysis and hydration
b) solubility and solubility product
4. Calculate the solubility of BaSO4 if its Ksp value is 1.1 x 10-10
5. State (i) Henry’s law (ii) LeChatelier’s principle
6. Classify the following as Lewis acid or Lewis base H2O , BF3 , Al3+ , Cl-
THREE MARKS QUESTIONS
1. The value of Kc = 6.2 at 750K for the reaction CO(g) + H2O(g) ⇌CO2(g) + H2(g). If initially the quantities of CO and H2O are 2 moles in a 1 liter vessel, What would be the equilibrium concentrations of all the chemicals?
2. (i) The Kc value for the reaction SO2 (g) + ½ O2 (g) ⇌ SO3 (g) is 72.5. What is the value of Kc for 2SO3(g) ⇌ 2SO2(g) + O2(g)?
(ii) If the Kp value for the reaction CO2(g) + C(s) ⇌ 2CO(g) at 1000K is 3, find value of Kc.
3. Calculate the degree of dissociation, pH, and concentration of all species at equilibrium of a 0.05M HCN solution if Ka = 4.9 x 10-10.
4. (i) If Ka for the weak acid niacin is 1.5 x 10-5, what is Kb for its conjugate base?
(ii) The pH of an acetic acid solution is 5.6. What is the concentration of the solution if Ka = 1.8 x 10-7?
5. 10ml of 0.1M CaCl2 is mixed with 15ml of 0.11M NaF. Predict whether CaF2 will precipitate if the Ksp of CaF2 is 5.3 x 10-9.
6. Which of the following is more soluble?
a) AgClor AgBr[ Ksp of AgCl = 1.8 x 10-10 ; AgBr = 5 x 10-13]
b) AgCNor Ni(OH)2 [ KspAgCN = 2 x 10-15; Ni(OH)2 = 6 x 10-17]
7. A buffer solution contains 0.4mol of ammonium hydroxide and 0.5mol of ammonium chloride to make a buffer solution of 1L.Calculate the pH of the resulting buffer solution. Dissociation constant of ammonium hydroxide at 25oC is 1.81x 10-5
VALUE BASED QUESTION ( FOUR MARKS)
1. In group III, the cationsFe, and Al are precipitated as hydroxides by the addition of NH4OH to the aqueous solution of the mixture. But a small amount of NH4Cl is added before the addition of NH4OH. Arvinderwas confused to see why common NH4+ ion is added. He asked his friend Palvinder the purpose of adding common NH4+ ion. Palvinder explained the purpose of adding NH4Cl and then Arvinder got satisfied.
(i) What would be the answer of Palvinder.
(ii) Why magnesium is not precipitated from a solution of it’s salt in group III.
(iii)What is basic principle behind the systematic analysis of cations and group separation? Explain.
(iv)What values are shown by Palvinder?
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