Le Chatelier Principles

What is a property of a reaction that has reached equilibrium?

• The rate of the forward reaction is equal to the rate of the reverse reaction

• The rate of the forward reaction if greater than the rate of the reverse reaction

• The amount of products is equal to the amount of reactants

• The amount of products is greater than the amount of reactants

Given the reaction at equilibrium: 2CO(g) + O2(g) <-> 2CO2(g) When the reaction is subjected to stress, a change will occur in the concentration of

• neither reactants nor products

• products, only

• reactants, only

• both reactants and products

In which reaction will the point of equilibrium shift to the left when the pressure on the system is increased?

• 2Mg(s) + O2(g) <-> 2MgO(s)

• 2H2(g) + O2(g) <-> 2H2O(g)

• C(s) + O2(g) <-> CO2(g)

• CaCO3(s) <-> CaO(s) + CO2(g)

Given the reaction at equilibrium: 2 SO2(g) + O2(g) <-> 2 SO3(g) + heat. Which change will shift the equilibrium to the right?

• increasing the temperature

• adding a catalyst

• adding more O2(g)

• decreasing the pressure

Given the reaction A2(g) + B2(g) <--> 2AB(g) + heat. An increase in the concentration of A2(g) will

• ncrease the production of B2(g)

• decrease the production of AB(g)

• increase the frequency of collisions between A2(g) and B2(g)

• decrease the frequency of collisions between A2(g) and B2(g)

Given the reaction at equilibrium: N2(g) + 3 H2(g) <--> 2 NH3 (g). If the pressure is increased at constant temperature, there will be an increase in the number of moles of

• both N2(g) and H2(g)

• N2(g), only

• NH3 (g), only

• H2(g), only

Given the equilibrium reaction in a closed system: H2(g) + I2(g) + heat <--> 2 HI(g). What will be the result of an increase in temperature?

• The equilibrium will shift to the left and [H2] will increase

• The equilibrium will shift to the left and [H2] will decrease

• The equilibrium will shift to the right and [HI] will decrease

• The equilibrium will shift to the right and [HI] will increase

AgCl(s) + heat <--> Ag+(aq) + Cl-(aq). Which change will cause an increase in the amount of AgCl(s)?

• a decrease in the concentration of Ag+(aq)

• an increase in the concentration of Cl-(aq)

• an increase in temperature

• a decrease in pressure

Given the reaction at equilibrium: 1/2 N2(g) +1/2 O2(g) + 21.6 kJ <--> NO(g). The equilibrium will shift to the right if the

• pressure increases

• temperature decreases

• temperature increases

• pressure decreases

A reaction will be spontaneous if it results in products that have

• greater potential energy and more randomness

• lower potential energy and less randomness

• lower potential energy and more randomness

• greater potential energy and less randomness