Explain why pure liquids and solids can be ignored while writing the value of equilibrium constants.
This is because molar concentration of a pine solid or liquid is independent of the amount present.
Since density of pure liquid or solid is fixed and molar mass is also fixed. Therefore molar concentration are constant.
Arrange the following in increasing order of pH.
KN03(aq), CH3COONa(aq), NH4Cl(aq), C6H5COONH4(aq)
Predict which of the following will have appreciable concentration of reactants and products:
Calculate the volume of water required to dissolve 0.1 g lead (II) chloride to get a saturated solution. (Ksp of PbCl2 = 3.2 x 10-8, atomic mass of Pb = 207 u).
For the following equilibrium, K =6.3 x 1014 at 1000 K. NO(g)+O3 —–>NO2(g) + O2(g) Both the forward and reverse reactions in the equilibrium are elementary bimolecular reactions. What is Kc for the reverse reaction ?
The species H20, HCO3–, HSO4– and NH3 can act both as Bronsted acid and base. For each case, give the corresponding conjugate acid and base.
The value of Kc for the reaction 302(g) —>203(g) is 2.0 x 10-50 at 25 °C. If equilibrium concentration of 02 in air at 25 °C is 1.6 x 10-2, what is the concentration of O3?
PCl5, PCl3 and Cl2 are at equilibrium at 500 K and having concentration 1.59M PCl5 1.59M Cl2 and 1.41M PCl5. Calculate Kc for the reaction PCl5———>PC13+ Cl2
On the basis of the equation pH = -log [H+], the pH of 10-8 mol dm-3 solution of HC1 should be 8. However, it is observed to be less than 7.0. Explain the reason.
Calculate the pH of the following solutions:
(a) 2g ofTlOH dissolved in water to give 2 litre of the solution
(b) 0.3 g of Ca(OH)2 dissolved in water to give 500 mL of the solution
(c) 0.3 g of NaOH dissolved in water to give 200 mL of the solution
(d) l mL of 13.6 M HCl is diluted with water to give 1 litre of the solution.
The value of Kc for the reaction 2A——>B + C is 2 x 10-3. At a given time, the composition of reaction mixture is [A] = [B] = [C] = 3 x 10-4 M. In which direction the reaction will proceed?
For the reaction N204(g) ⇌2N02(g), the value of K is 50 at 400 K and 1700 at 500 K. Which of the following options is correct?
(a) The reaction is endothermic.
(b) The reaction is exothermic.
(c) If NO2(g) and N204(g) are mixed 400 K at partial pressures 20 bar and 2 bar respectively, more N204(g) will be formed.
(d) The entropy of the system increases.
A mixture of 1.57 mol of N2, 1.92 mol of H2 and 8.13 mol of NH3is introduced into a 20 L reaction vessel at 500 K. At this temperature, the equilibrium constant Kc for the reaction
Is this reaction at equilibrium? If not, what is the direction of net reaction?
What is the effect of:
(i) addition of H2 (ii) addition of CH3OH
(iii) removal of CO (iv) removal of CH3OH
In the reaction A + B———> C + D, what will happen to the equilibrium if concentration of A is increased?
(b) The equilibrium constant for a reaction is 2 x 10-23 at 25 °C and 2 x 10-2 at 50 °C. Is the reaction endothermic or exothermic?
(c) Mention at least three ways by which the concentration of S03 can be increased in the following reaction in a state of equilibrium.
A sparingly soluble salt gets precipitated only when the product of concentration of its ions in the solution (Qsp) becomes greater than its solubility product. If the solubility of BaS04 in water is 8 x 10-4 mol dm-3, calculate its solubility in 0.01 mol dm-3 of H2S04.
The solubility product of Al(OH)3 is 2.7 x 10-11. Calculate its solubility in g–L and also find out pH of this solution. (Atomic mass of A1 = 27 u).
The value of Kc for the reaction
2HI(g) ⇌H2(g) + I2(g) is 1 x 10-4. At a given time, the composition of reaction mixture is [HI] = 2 x 10-5 mol, [H2] = 1 x 10-5 mol and [I2] = 1 x 10-5 mol. In which direction will the reaction proceed?
pH of a solution of a strong acid is 5.0. What will be the pH of the solution obtained after diluting the given solution a 100 times?
Hydrogen gas is obtained from the natural gas by partial oxidation with steam as per following endothermic reaction:
Write the expression for Kpfor the above reaction
How will the value of Kp and composition of equilibrium mixture be affected by:
(i) increasing the pressure, (ii) increasing the temperature, (iii) using a catalyst?
The pH of0.005 M codeine (C18H21N03) solution is 9.95. Calculate the ionization constant and PKb.
Given the equilibrium N2O4 (g) ——->2NO2 (g) K=0.15 atm at 298 K
(a) What is Kp using pressure in torr?
(b) What is Kc using units of moles per litre.
Conjugate acid of a weak base is always stronger. What will be the decreasing order of basic strength of the following conjugate bases?
OH–, RO–, ch3coo– , cl–
What is meant by conjugate acid-base pair? Find the conjugate acid/base for the following species: HNO2, CH–, HClO4 , OH–, CO32-, S2-
The ionization constant of HF, HCOOH and HCN at 298 K are is 6.8 x 10-4 , 1.8 x 10-4 and 4.8 x 10-9 respectively, Calculate the ionization constant of the corresponding conjugate base.
A liquid is in equilibrium with its vapours in a sealed container at a fixed temperature. The volume of the container is suddenly increased, (i) What is the initial effect of the change on the vapour pressure? (ii) How do the rates of evaporation and condensation change initially? (iii) What happens when equilibrium is restored finally and what will be the final vapour pressure?
The equilibrium constant expression for a gas reaction is,
Write the balanced chemical equation corresponding to this expression.
(i) Define Le Chatelier’s principle.
(ii) Following reactions occur in a Blast furnace.
Fe203(s) + 3CO(g) ———–>2Fe(s) + 3CO2(g)
use Le chatelier’s principle to predict the direction of reaction when equilibrium mixture is disturbed by
(a) adding Fe203 (b) removing CO2 .
(c) removing CO.
For the equilibrium 2 NOCl(g)——-> 2NO(g) + Cl2(g) the value of the equilibrium constant Kc is 3.75 x 10-6 at 1069 K. Calculate the Kp for the reaction at this temperature?
Following data is given for the reaction:
CaC03(s) → CaO(s) + C02(g)
∆fH ° [CaO(s)] = -635.1 kJ mol–1
∆fH ° [COz(g)] = -393.5 kJ mol–1
∆fH ° [CaC03(s)] = -1206.9 kJ mol–1
Predict the effect of temperature on the equilibrium constant of the above reaction.
Match the following equilibria with the corresponding condition
| Column I | Column II | ||
| (i) | Liquid⇌Vapour | (a) | Saturated solution |
| (ii) | Solid ⇌Liquid | (b) | Boiling point |
| (iii) | Solid ⇌Vapour | (c) | Sublimation point |
| (iv) | Solute(s) ⇌Solute (solution) | (d) | Melting point ‘ |
| (e) | Unsaturated solution | ||
Explain why pure liquids and solids can be ignored while writing the value of equilibrium constants.
Reaction between nitrogen and oxygen takes place as follows:
If a mixture of 0.482 mol of N2 and 0.933 mol of O2 is placed in a reaction vessel of volume 10 L and allowed to form N2O at a temperature for which Kc – 2.0 x 10-37, determine the composition of the equilibrium mixture.
Nitric oxide reacts with bromine and gives nitrosyl bromide as per reaction given below:
When 0.087 mole of NO and 0.0437 mole of Br2 are mixed in a closed container at constant temperature, 0.0518 mole of NOBr is obtained at equilibrium. Determine the compositions of the equilibrium mixture.
A sample of HI (g) is placed in a flask at a pressure of 0.2 atm. At equilibrium partial pressure of HI (g) is 0.04 atm. What is Kp for the given equilibrium?
What is the equilibrium concentration of each of the substances in the equilibrium when the initial concentration of ICl was 0.78 M?
At 473 K, the equilibrium constant Kc for the decomposition of phosphorus pentachloride (PCl5) is 8.3 x 10-3 . if decomposition proceeds as:
(a) Write an expression for Kc for the reaction
(b) What is the value of Kc for the reverse reaction at the same temperature.
(c) What would be the effect on Kc if
(i) More of PCl5is added (ii) Temperature is increased.
