Write the expressions for the equilibrium constants of the reactions below.
a. N2 (ππ) + 3H2 (ππ) β 2NH3 (ππ)
b. Br2 (ππ) + H2 (ππ) β 2HBr (ππ)
c. CO(ππ) + H2O(ππ) β H2 (ππ) + CO2
How will the equilibrium shift if the following changes are made? State if the reaction will shift to the left or right and explain why it will shift in that direction.
PCl5 (ππ) + heat β PCl3 (ππ) + Cl2 (ππ)
a. Temperature is increased
Pressure is increased
c. Cl2 is added
d. PCl3 is removed as it is formed
3. How will the equilibrium shift if the following changes are made? State if the reaction will shift
to the left or right and explain why it will shift in that direction.
H2 (ππ) + Cl2 (ππ) β 2HCl(ππ) + heat
a. Heat is removed
b. HCl is added
c. H2 is added
d. Pressure is decreased
Use the reaction below to answer the following questions.
2NO2 (ππ) β N2O4 (ππ)
a. What is the expression for the equilibrium constant, Keq, for the reaction?
b. If there are 0.400 moles of N2O4 and 0.500 moles of NO2 in a 1.00 L flask at equilibrium at 20Β°C,
what is the Keq?
No work on your part. No guess about your first step. This looks like a homework dump. So I'll give you my thoughts and let you finish.
1. Keq. Multiply the molar concentrations of the products of the reaction and divide all of that by the product of the molar concentrations of the reactants. Raise each concentration by a power shown by the coefficient in the balanced equation. That is Keq. You didn't say what kind of Keq. If Kc you want to use molar concentrations. If Kp you want to use the partial pressure of each gas. For example; Kc for N2 (ππ) + 3H2 (ππ) β 2NH3 (ππ)
Kc = (NH3)^2/(N2)(H2)^3
2. I don't know what gg stands for. I assume gas. Here is what you want to know about Le Chatelier's Principle and what that has to do with shifting equilibrium to the right or left. Here is the principle in eloquent language. When a stress is applied to a chemical reaction in equilibrium the system will shift is such a direction so as to relieve the stress. Now here is a less eloquent statement but one that gets to the nitty gritty. A system at equilibrium will try to undo what we do to it.
PCl5 (ππ) + heat β PCl3 (ππ) + Cl2 (ππ)
a. The reaction uses heat to make the products. So if you add heat it will shift to the right and make more products to use up the heat that has been added.
c. Adding Cl2 will make the rxn shift to the left. The reaction produces Cl2 so it will try to get rid of whatever you've added. It can do that by pushing the rxn to the left so as to use up the added Cl2.
You do the others.
3 and 4. Done above. You should be able to do 3 and 4 from the above instructions.
5. 2NO2 (ππ) β N2O4 (ππ)
a. Kc = (N2O4)/(NO2)^2
b.(N2O4) = 0.400 mol in 1 L = 0.400 mol/L = 0.400 M. (NO2) = 0.500 mol/L = 0.500 M from the problem.
c. Kc = (0.400)/(0.500)^2 = 0.400/0.25 = ?
I want to see your work if you run into trouble with any of these. I shall be happy to check your answers if you post your work with them. Good luck.
a. The expression for the equilibrium constant, Keq, can be written using the concentrations of the reactants and products in the balanced equation.
a. Keq = [NH3]^2 / ([N2] * [H2]^3)
b. Keq = [HBr]^2 / ([Br2] * [H2])
c. Keq = [H2] * [CO2] / ([CO] * [H2O])
To determine how the equilibrium will shift, we need to consider the factors that affect the equilibrium position.
a. When the temperature is increased, the reaction will shift in the endothermic direction to absorb the excess heat, so it will shift to the right (forward reaction).
b. When the pressure is increased, the reaction will shift to the side with fewer gas molecules to decrease the pressure, so it will shift to the right (forward reaction).
c. When Cl2 is added, it will shift the equilibrium to the right (forward reaction) because the increased concentration of Cl2 will cause the reaction to consume more of it to reach equilibrium.
d. When PCl3 is removed, it will shift the equilibrium to the left (reverse reaction) because the removal of PCl3 disrupts the equilibrium, and the reaction will proceed in the reverse direction to replenish the PCl3 concentration.
The same principles can be applied to the second set of questions:
a. When heat is removed, it will shift the equilibrium to the left (reverse reaction) as the exothermic reaction generates heat to compensate for the loss.
b. When HCl is added, it will shift the equilibrium to the left (reverse reaction) to use up the excess HCl.
c. When H2 is added, it will shift the equilibrium to the right (forward reaction) to consume the excess H2 and maintain the equilibrium.
d. When the pressure is decreased, the equilibrium will shift to the side with more moles of gas, so it will shift to the right (forward reaction).
For the third question:
a. The expression for the equilibrium constant Keq is Keq = [N2O4] / [NO2]^2
b. Given the concentrations:
[N2O4] = 0.400 moles / 1.00 L = 0.400 M
[NO2] = 0.500 moles / 1.00 L = 0.500 M
Keq = 0.400 / (0.500^2) = 1.60 M^2