chapter 7: extent of chemical reactions Flashcards
what are irreversible reactions?
irreversible reactions can only proceed in one direction and cannot be reversed (reactants can only be converted into products, not products back to reactants)
what are reversible reactions?
reversible reactions can proceed both forwards and backwards to a considerable extent
what is an example of a reversible reaction?
the Haber-Bosch process, where ammonia is created from hydrogen and nitrogen gas
what is meant by rate of reaction?
rate of reaction refers to how much product is formed over a given period of time.
what can rate of reaction be influenced by?
temperature, concentration, pressure and catalysts
what is the extent of reaction?
extent of reaction refers to proportion of reactants that have been converted into products.
what is rate of reaction important to learning for?
for understanding the kinetics of a reaction and the factors that influence it.
what is extent of reaction important to learning for?
extent of a reaction is important for understanding the yield of a reaction
what is an open system?
in which matter and energy can be exchanged with the surroundings
what is a closed system?
in which only energy is exchanged with the surroundings
what does it mean by the yield of reaction?
amount of product obtained in a chemical reaction
what is meant by a dynamic state of equilibrium?
in closed systems, dynamic equilibrium refers to when the forward and reverse reactions have not ceased, rather they occur simultaneously
what are some things that happen during a dynamic equilibrium?
- as reactants and products are being produced at the same rate, there is no net change in the concentration of the products or reactants.
- the reaction is deemed incomplete, and all of the substances are present in the equilibrium mixture.
- temperature of the system is constant as heat is being absorbed at the same rate it is being released
- pressure of system is constant as number of gas particles is constant
what does the equilibrium constant “K” represent?
it is the ratio of concentrations of products to the ratio of concentrations of reactants in a reaction.
what do large K values represent?
reaction has progressed to considerable extent. there is a significant concentration of product in reaction system
what do small K values represent?
reaction has not proceeded to a considerable extent and there is a considerable proportion of reactants present.
how can we represent equilibrium reactions?
system reaching equilibrium can be represented by both concentration time graphs and rate time graphs.
what is the only factor that affects K and why?
temperature. temperature changes alter the energy available to the system, when energy available to system is altered, reactants and products adjust to share that energy, which affects ratio of products to reactants in the system
what happens when forward reaction is endothermic?
there is an increase in temperature, which leads to an increase in the extent of the reaction, and hence an increase in the value of K
what happens when forward reaction is exothermic?
increase in temperature leads to decrease in the extent of reaction, and a decrease in the value of K
what is Q?
Q is a reaction quotient that serves as a quantitative measure of the extent of a reaction.
what happens when Q<K
forward reaction is favoured and system shifts to the right
what happens when Q = K?
Equilibrium
what happens when Q > K
Reverse reaction is favoured (shifts left)
