Question

Questions

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.

2K2Cr4 + 2HCl ------> Cr2o7 + H2O + 2KCl

Use the information below to answer Questions C, D, and E:

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.

N2 + 3H2 ------> 2NH3

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 equilibrium position would shift.

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 equilibrium position would shift.

If the concentration of the product NH₃ was decreased from 1.0 x 10^-4 M to 5.6 x 10^-3M, calculate the reaction quotient (Q) and determine which way the equilibrium position would shift.

Answer 1

A. Hydrochloric acid is much stronger than chromic acid, the conjugate of potassium chromate. Accordingly, the forward reaction below will be favored:

K2CrO4 + 2HCl ---> 2KCl + H2CrO4
(Potassium chromate) (Hydrochloric acid) (Potassium chloride) (Chromic acid)

It is an Acid-Base(acid- HCl, base-K2Cro4) reaction which always results in the formation of salt(KCl)

Adding an acid will increase the concentration of H3O+ ions in the equilibrium system, forcing the equilibrium to shift to the right, or product side. This is demonstrated by the solution becoming orange. So is exothermic.

The exothermic reactions are more common than endothermic. Endothermic reactions usually occur if you are reversing a reaction. An exception is dissolving a crystal where the crystal lattice energy breakdown yields more entropy than taking heat from the surroundings.

B. the equilibrim expression is products over reactants. they are multiplied and the coefficients become powers. solids and liquids dont count.