Equilibrium

Find out the value of $K_c$ for each of the following equilibria from the value of $K_p$: (i) $2NOCl(g) \rightleftharpoons 2NO(g) + Cl_2(g)$; $K_p = 1.8 \times 10^{-2}$ at 500 K (ii) $CaCO_3(s) \rightleftharpoons CaO(s) + CO_2(g)$; $K_p = 167$ at 1073 K

Reaction between $N_2$ and $O_2$ takes place as follows: $2N_2 (g) + O_2 (g) \rightleftharpoons 2N_2O (g)$ If a mixture of 0.482 mol $N_2$ and 0.933 mol of $O_2$ is placed in a 10 L reaction vessel and allowed to form $N_2O$ at a temperature for which $K_c = 2.0 \times 10^{-37}$, determine the composition of equilibrium mixture.

A sample of HI(g) is placed in flask at a pressure of 0.2 atm. At equilibrium the partial pressure of HI(g) is 0.04 atm. What is $K_p$ for the given equilibrium? $2HI (g) \rightleftharpoons H_2 (g) + I_2 (g)$

The equilibrium constant expression for a gas reaction is, $K_c = \frac{[NH_3]^4 [O_2]^5}{[NO]^4 [H_2O]^6}$ Write the balanced chemical equation corresponding to this expression.

At 700 K, equilibrium constant for the reaction: $H_2 (g) + I_2 (g) \rightleftharpoons 2HI (g)$ is 54.8. If 0.5 mol L$^{-1}$ of HI(g) is present at equilibrium at 700 K, what are the concentration of $H_2(g)$ and $I_2(g)$ assuming that we initially started with HI(g) and allowed it to reach equilibrium at 700 K?

Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as: $CH_3COOH (l) + C_2H_5OH (l) \rightleftharpoons CH_3COOC_2H_5(l) + H_2O (l)$ (i) Write the concentration ratio (reaction quotient), $Q_c$, for this reaction (note: water is not in excess and is not a solvent in this reaction) (ii) At 293 K, if one starts with 1.00 mol of acetic acid and 0.18 mol of ethanol, there is 0.171 mol of ethyl acetate in the final equilibrium mixture. Calculate the equilibrium constant. (iii) Starting with 0.5 mol of ethanol and 1.0 mol of acetic acid and maintaining it at 293 K, 0.214 mol of ethyl acetate is found after sometime. Has equilibrium been reached?

One of the reaction that takes place in producing steel from iron ore is the reduction of iron(II) oxide by carbon monoxide to give iron metal and CO$_2$. $FeO (s) + CO (g) \rightleftharpoons Fe (s) + CO_2(g); \quad K_p = 0.265 \text{ atm at 1050 K}$ What are the equilibrium partial pressures of CO and CO$_2$ at 1050 K if the initial partial pressures are: $p_{CO} = 1.4$ atm and $p_{CO_2} = 0.80$ atm?

Bromine monochloride, BrCl decomposes into bromine and chlorine and reaches the equilibrium: $2BrCl (g) \rightleftharpoons Br_2(g) + Cl_2(g)$ for which $K_c = 32$ at 500 K. If initially pure BrCl is present at a concentration of $3.3 \times 10^{-3}$ mol L$^{-1}$, what is its molar concentration in the mixture at equilibrium?

At 1127 K and 1 atm pressure, a gaseous mixture of CO and CO$_2$ in equilibrium with soild carbon has 90.55% CO by mass $C (s) + CO_2(g) \rightleftharpoons 2CO (g)$ Calculate $K_c$ for this reaction at the above temperature.

Calculate a) $\Delta G^\circ$ and b) the equilibrium constant for the formation of NO$_2$ from NO and O$_2$ at 298K $NO (g) + \frac{1}{2} O_2 (g) \rightleftharpoons NO_2 (g)$ where $\Delta G^\circ (NO_2) = 52.0 \text{ kJ/mol}$ $\Delta G^\circ (NO) = 87.0 \text{ kJ/mol}$ $\Delta G^\circ (O_2) = 0 \text{ kJ/mol}$

Which of the following reactions will get affected by increasing the pressure? Also, mention whether change will cause the reaction to go into forward or backward direction. (i) $COCl_2 (g) \rightleftharpoons CO (g) + Cl_2 (g)$ (ii) $CH_4 (g) + 2S_2 (g) \rightleftharpoons CS_2 (g) + 2H_2S (g)$ (iii) $CO_2 (g) + C (s) \rightleftharpoons 2CO (g)$ (iv) $2H_2 (g) + CO (g) \rightleftharpoons CH_3OH (g)$ (v) $CaCO_3 (s) \rightleftharpoons CaO (s) + CO_2 (g)$ (vi) $4NH_3 (g) + 5O_2 (g) \rightleftharpoons 4NO (g) + 6H_2O (g)$

Dihydrogen gas is obtained from natural gas by partial oxidation with steam as per following endothermic reaction: $CH_4 (g) + H_2O (g) \rightleftharpoons CO (g) + 3H_2 (g)$ (a) Write as expression for Kp for the above reaction. (b) How will the values of Kp and composition of equilibrium mixture be affected by (i) increasing the pressure (ii) increasing the temperature (iii) using a catalyst?

At 473 K, equilibrium constant $K_c$ for decomposition of phosphorus pentachloride, $PCl_5$ is $8.3 \times 10^{-3}$. If decomposition is depicted as, $PCl_5(g) \rightleftharpoons PCl_3(g) + Cl_2(g) \quad \Delta_r H^\circ = 124.0 \text{ kJ mol}^{-1}$ 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 $K_c$ if (i) more PCl$_5$ is added (ii) pressure is increased (iii) the temperature is increased?

Predict which of the following reaction will have appreciable concentration of reactants and products: a) $Cl_2(g) \rightleftharpoons 2Cl(g)$ $K_c = 5 \times 10^{-39}$ b) $Cl_2(g) + 2NO(g) \rightleftharpoons 2NOCl(g)$ $K_c = 3.7 \times 10^8$ c) $Cl_2(g) + 2NO_2(g) \rightleftharpoons 2NO_2Cl(g)$ $K_c = 1.8$

What is meant by the conjugate acid-base pair? Find the conjugate acid/base for the following species: $HNO_2, CN^-, HClO_4, F^-, OH^-, CO_3^{2-}, \text{and S}^{2-}$

What will be the conjugate bases for the Brönsted acids: HF, $H_2SO_4$ and $HCO_3^-$?

The concentration of hydrogen ion in a sample of soft drink is $3.8 \times 10^{-3}$ M. What is its pH?

The ionization constant of HF, HCOOH and HCN at 298K are $6.8 \times 10^{-4}, 1.8 \times 10^{-4}$ and $4.8 \times 10^{-9}$ respectively. Calculate the ionization constants of the corresponding conjugate base.

The first ionization constant of H$_2$S is $9.1 \times 10^{-8}$. Calculate the concentration of HS$^{-}$ ion in its 0.1 M solution. How will this concentration be affected if the solution is 0.1 M in HCl also? If the second dissociation constant of H$_2$S is $1.2 \times 10^{-13}$, calculate the concentration of S$^{2-}$ under both conditions.

At a certain temperature and total pressure of $10^5$ Pa, iodine vapour contains 40% by volume of I atoms $I_2(g) \rightleftharpoons 2I(g)$ Calculate $K_p$ for the equilibrium.