SCH4U Unit 3 - Equilibrium Exam Questions with Correct Answers Latest Update

SCH4U Unit 3 - Equilibrium Exam Questions with Correct Answers Latest Update What is equilibrium? - Answers A state the rates of the forward and reverse reactions are equal What are the 4 conditions of equilibrium? - Answers 1. Rates of forward and reverse reactions are the same 2. macroscopic properties (pH, temp, conc.) are constant 3. No input or escape of any component (closed system) 4. Equilibrium can be achieved from either direction Homogenous vs heterogenous equilibriums - Answers Homogenous: all reactants and products are the same state Heterogenous: all reactants and products are not the same state What is favourability? - Answers when something has a natural tendency to occur more likely than others. favourability is necessary for a reaction to establish equilibrium What are the 3 factors of favourability? - Answers Enthalpy, temperature, and entropy How does enthalpy impact favourability? - Answers Exothermic reactions are more favoured because they have lower activation energy requirements. however, some endothermic reactions can still occur spontaneously How does temperature impact favourability? - Answers Endothermic reactions are more favourable at higher temperatures. Exothermic reactions are more favourable at lower temperatures. What is entropy? How does entropy impact favourability? - Answers Entropy is the measure of energy that spreads out in a reaction. Entropy is directly proportional to disorder/chaos in a reaction. Disorder and chaos make a reaction more favourable, all favourable changes done to a reaction involve some sort of increase in entropy. What is the first law of thermodynamics? - Answers Enthalpy is conserved, entropy is not What is the second law of thermodynamics? - Answers Total entropy of the universe is constantly increasing, whereas enthalpy is constant Which states of matter have more disorder? - Answers Gas Liquid Solids What happens leading up to equilibrium and what happens at? - Answers Before equilibrium, the concentrations of the reactants and products are changing. Once at equilibrium, these concentrations are constant and the forward and reverse reactions are happening at the same time. What is the equilibrium constant K? - Answers the relationship between the concentration of the products and the concentration of the reactants What is the law of mass action? - Answers Kc [C][D]/[A][B] What do you do for a heterogeneous equation when calculating the equilibrium constant K? - Answers Get rid of the non aq or gas compounds How do K values impact favourability? - Answers When K 1, the reaction is product favoured When K 1, the reaction is reactant favoured What is Le Chatelier's principle? - Answers When an equilibrium system is disturbed, the system will shift its equilibrium position to counteract the disturbance and re-establish equilibrium What are some possible disruptions to an equilibrium? - Answers Change in temperature, pressure, or concentration of any of the reactants or products How does change in concentration impact an equilibrium? - Answers If the concentration of reactants is increased, equilibrium will shift to produce more product. If the concentration of products is increased, the equilibrium will shift to reverse the reaction, shifting to the reactants side. How does change in pressure impact an equilibrium? - Answers If pressure is increased, the equilibrium shifts to the side with fewer molecules. If pressure is decreases, the equilibrium shifts to the side with more molecules.