Chapter 10 - Reversible Reactions and Equilibrium (10.1 - 10.2) Flashcards
What can you do in a reversible reaction?
You can change the direction of the reaction by changing the reaction conditions
What is a forward reaction
Reaction occurs from left to right
What is a backward reaction
Reaction occurs from right to left
What is a closed system
A set up where no molecules can escape
What is equilibrium
State of a reaction where there is no overall change. The amount of products and reactants remain the same.
Conditions for a reversible reaction to be in equilibrium in a closed system (2 conditions)
1) The forward and reverse reactions take place at the same rate
2) The concentrations of reactants and products are no longer changing
What happens when you change a condition the reversible reaction in equilibirum
The system acts to oppose the change and restore equilibrium. A new equilibrium mixture forms.
What are the conditions you can change to shift the equilibrium
Change in temp
Change in concentration
Change in pressure
Explain how changing the temperature shifts the equilibrium
Increasing the temp
Decreasing the temp
Equilibrium shifts based on weather the forward or backward reaction is endo (give out heat) /exothermic (take in heat).
eg: N2 + 3H2 <—-> 2NH3 (ammonia)
forward reaction - exo
backward reaction - endo
Increasing the temp (can j write this in the exam) - The backward reaction would be favored since the reaction is endothermic and the equilibrium would shift from right to left. The yield decreases.
(explanation: The system wants to maintain constant conditions. Adding heat would mean that the system is hotter. Hence the system would try to use up the excess heat. In an endothermic reaction, heat is used up. Hence after the endothermic reaction takes place the system would return to its initial temperature. Yield decreases since the backward reaction to give the products is occurring more frequently.)
Decreasing the temp - The forward reaction would be favored since it is exothermic. The equilibrium would shift from the left to right and the yield would increase.
(explanation: similar to previous. The system wants to maintain constant temp, and hence when temp is reduced it favors the exothermic reaction which produces heat and would heat the system back up eventually to the initial constant temperature.)
How does changing pressure shift the equilibrium of the reaction
Increasing the pressure
Decreasing the pressure
which state of matter
ONLY FOR GASSES
Equilibrium shifts based on which side has more molecules
eg: N2 + 3H2 <—-> 2NH3 (ammonia)
left side - 4 moles
right side - 2 moles
When pressure is increased the forward reaction is favored since it has more particles. The equilibrium shifts from right to left and the yield increases.
(If pressure increases and there are more molecules, the system wants to maintain a constant volume hence the forward reaction takes place so that there are half the number of molecules and the constant volume can be maintained.)
When pressure is decreased the backward reaction is favored since it has fewer particles. The equilibrium shifts from right to left and yield decreases.
How does changing concentration shift the equilibrium
When the concentration of products is reduced/concentration of reactants is increased, the system converts more reactants to products to maintain a constant level both. The forward reaction is favored and the equilibrium shifts from left to right
vice versa
How does a catalyst influence a reaction
Speeds up the reaction but doesn’t shift equilibrium. Time is saved but yield doesn’t change.
why do the concentrations of the products and reactants at equilibrium not change
as the rate at which the product is formed by the forward reaction, equals the rate of it decomposing/reacting rate of forward reaction = rate of backward reaction
What happens when you heat up hydrated compounds
endo or exo forward reaction
water is driven off
endothermic forward reaction
Do hydrated compounds and their respective anhydrous compounds have reversible reactions?
give 2 examples
state chemical eqns
state colour changes
state forward reaction type(endo or exo)
Yes
CuSO4.5H2O ⇌ CuSO4 + 5H2O
blue ⇌ white + water
forward - endo
CoCl2.6H2O ⇌ CoCl2 + 6H2O
pink ⇌ blue
forward endo
