Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

Data Table 2: A. Use your results to determine if the forward reaction in the po

ID: 1009986 • Letter: D

Question

Data Table 2:

A.      Use your results to determine if the forward reaction in the potassium chromate/HCl reaction endothermic or exothermic. Explain your answer, using Table 1 to help construct your thoughts.

B.         Write the equation for the equilibrium constant (K) of the reaction studied in this exercise.

2 K2CrO4 + 2HCl                  Cr2O7             + H2O + 2KCl

Chromate                               Dichromate



Use the information below to answer Questions 3, 4, and 5:


The equilibrium constant (K) of the reaction below is K = 6.0 x 10-2, with initial concentrations as follows: [H2] = 1.0 x 10-2 M, [N2] = 4.0 M, and [NH3] = 1.0 x 10-4M.


C.         If the concentration of the reactant H2 was increased from 1.0 x 10-2 M to 2.5 x 10-1M, calculate the reaction quotient (Q) and determine which way the chemical system would shift.

D.         If the concentration of the reactant H2 was decreased from 1.0 x 10-2 M to 2.7 x 10-4M, calculate the reaction quotient (Q) and determine which way the chemical system would shift.

E.         If the concentration of the product NH3 was increased from 1.0 x 10-4 M to 5.6 x 10-3M, calculate the reaction quotient (Q) and determine which way the chemical system would shift.

Im having a hard time understanding this.

Color of Chromate Color of Dichromate Number of drops of NaOH to shift chemical system yellow Orange 5

Explanation / Answer

(A): Since the reaction proceeds towards the right(product side) under hot water bath (higher temperature), the reaction needs heat to proceed towards right. Hence the reaction is endothermic reaction.

(B): Equilibrium constant is written on the basis of the net ionic equation. The net ionic equation is

2CrO42-(aq) + 2H+(aq) ------- > Cr2O72-(aq) + H2O

Hence equilibrium constant K = [Cr2O72-(aq)] / ([CrO42-(aq)]2x[H+(aq)]2) (answer)

(C): Given the new concentration of H2, [H2]' = 2.5x10-1 M

For the given reaction, reaction quotient, Q = [NH3(g)]2 / [N2(g)]x[H2(g)]3

=> Q = (1.0x10-4 M)2 / (4.0 M)x(2.5x10-1 M)3

=> Q = 1.6x10-7 (answer)

Since Q < K, to increase the value to Q the reaction will move towards product side (answer).

(D):

Given the new concentration of H2, [H2]' = 2.7x10-4 M

For the given reaction, reaction quotient, Q = [NH3(g)]2 / [N2(g)]x[H2(g)]3

=> Q = (1.0x10-4 M)2 / (4.0 M)x(2.7x10-4 M)3

=> Q = 1.27x102 (answer)

Since Q > K, to decrease the value to Q the reaction will move towards reactant side (answer).

(E):

Given the new concentration of H2, [H2]' = 5.6x10-3 M

For the given reaction, reaction quotient, Q = [NH3(g)]2 / [N2(g)]x[H2(g)]3

=> Q = (1.0x10-4 M)2 / (4.0 M)x(5.6x10-3 M)3

=> Q = 1.423x10-2 (answer)

Since Q < K, to increase the value to Q the reaction will move towards product side (answer).