Law of chemical equilibrium, Kp and Kc
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See all →- For the reaction A(g) ⇌ 2B(g), the backward reaction rate constant is higher than the forward reaction rate constant by a factor of 2500, at 1000 K.[Given : R = 0.0831 L atm mol^-1 K^-1]K_p for the reaction at 1000 K is Answer: 3. 0.033 Key idea: K_c=k_f/k_b and K_p=K_c(RT)^(Δ n) . k_b=2500 k_f , so K_c=1/2500=4×10⁻⁴ . Δ n=2-1=1 ; RT=0.0831×1000=83.1 . K_p=4... 1
- Consider the following reaction in a sealed vessel at equilibrium with concentrations of N_2 = 3.0×10^-3 M, O_2 = 4.2×10^-3 M and NO = 2.8×10^-3 M.2NO_(g) ⇌ N_2(g) + O_2(g)If 0.1 mol L^-1 of NO_(g) is taken in a closed vessel, what will be degree of… Answer: 1. 0.717 Key idea: get K_c from the first data set, then use it for the new mixture. K_c=[N₂][O₂]/[NO]²=frac(3.0×10⁻³)(4.2×10⁻³)(2.8... 1
- For the reaction 2A ⇌ B + C, K_c = 4×10^-3. At a given time, the composition of reaction mixture is : [A]=[B]=[C]=2×10^-3 M.Then, which of the following is correct? Answer: 4. Reaction has a tendency to go in backward direction. Key idea: compare the reaction quotient Q_c with K_c . Q_c=[B][C]/[A]²=frac(... 1
- In which of the following equilibria, K_p and K_c are NOT equal? Answer: 2. PCl_(5(g)) ⇌ PCl_(3(g)) + Cl_(2(g)) Key idea: K_p=K_c(RT)^(Δ n_g) . They are equal only when Δ n_g=0 . 2BrCl⇌ Br₂+Cl₂ : Δ n_g=0 .... 1
- 3O_2(g) ⇌ 2O_3(g)for the above reaction at 298 K, K_c is found to be 3.0 × 10^-59. If the concentration of O_2 at equilibrium is 0.040 M then concentration of O_3 in M is Answer: 2. 4.38 × 10⁻³² Key idea: K_c=[O₃]²/[O₂]³ . [O₃]²=3.0×10⁻⁵⁹×(0.040)³=3.0×10⁻⁵⁹×6.4×10⁻⁵=1.92×10⁻⁶³ . [O₃]=sqrt1.92×10⁻⁶³=4.38×10⁻³²... 1
- The equilibrium constants of the following are :N_2 + 3H_2 ⇌ 2NH_3 K_1N_2 + O_2 ⇌ 2NO K_2H_2 + 1/2O_2 → H_2O K_3The equilibrium constant (K) of the reaction : 2NH_3 + 5/2O_2 K⇌ 2NO + 3H_2O, will be : Answer: 1. K₂K₃³/K₁ Key idea: combine reactions; reversing gives 1/K , multiplying by n gives Kⁿ , adding gives the product of K values. Tar... 1