Untitled Deck Flashcards
(23 cards)
How is the reaction rate measured?
Measured via a change in mass of reactants or products over time. Examples include mass lost by reagent, mass gained by products, volume of gas, pressure of gas, colour intensity, solution concentration, and pH.
What are the requirements for a reaction according to collision theory?
Particles must collide, collide with sufficient energy greater than the activation energy, and collide in the right orientation.
What factors affect reaction rate?
Surface area of solid reactants, concentration of reactants, gas pressure, temperature, and catalyst. And nature of reactants and agitation.
How does surface area of solid reactants affect reaction rate?
Increasing surface area increases the area of solid that can participate in reaction, thus increasing frequency of collisions and speeding up the reaction rate.
How does concentration of reactants affect reaction rate?
Increasing concentration increases the number of particles per unit volume, increasing the frequency of collisions and speeding up the reaction rate.
How does pressure affect reaction rate?
Increasing system pressure by decreasing volume increases the number of particles per unit volume, increasing frequency of collisions and speeding up the reaction rate.
How does temperature affect reaction rate?
Increasing temperature increases average kinetic energy of particles, leading to greater frequency of collisions and a greater proportion of successful collisions, thus speeding up the reaction rate.
What is the role of a catalyst in a reaction?
A catalyst provides an alternate reaction pathway with lower activation energy, allowing a greater proportion of particle collisions to overcome this new barrier, thus speeding up the reaction rate.
What is an open system in chemical equilibrium?
An open system exchanges energy and matter with the surroundings.
What is a closed system in chemical equilibrium?
A closed system only exchanges energy with the surroundings.
What is a reversible reaction?
A reversible reaction is one in which products can be converted back to reactants. The activation energy of the forward and reverse reaction must be similar and low.
What is chemical equilibrium?
Chemical equilibrium is achieved for a closed system when the rate of forward and reverse reactions is equal with constant reagent concentration.
Why is it called dynamic equilibrium?
It is referred to as dynamic equilibrium because the reaction is not complete, and there is still molecular level activity taking place.
What is the equilibrium constant (K)?
The equilibrium constant is determined by the ratio of concentration of products to reactants, excluding solids and liquids.
How does temperature affect the equilibrium constant (K)?
As temperature increases, K increases for endothermic reactions and decreases for exothermic reactions.
What does K > 1 indicate?
K > 1 indicates a greater product concentration than reactants at equilibrium.
What does K < 1 indicate?
K < 1 indicates a lower product concentration than reactants at equilibrium.
What is Le Chatelier’s principle (LCP)?
LCP states that if an equilibrium system is subjected to a change, the system will re-establish equilibrium in a way that partially counteracts the imposed change.
How does adding/removing reactant or product affect equilibrium?
The system re-establishes equilibrium by favouring the reaction pathway where there is a net consumption/production of the added/removed reactant or product.
How does changing pressure affect equilibrium in gas systems?
The system re-establishes equilibrium by favouring the consumption/production of the side with greater gaseous particles.
What is the effect of adding a catalyst on equilibrium?
Adding a catalyst increases the rate of both forward and reverse reactions by the same magnitude, resulting in no net change in equilibrium position.
What happens when water is added to an aqueous system?
Adding water causes dilution, and the system will favour the production of the side with greater aqueous particles to partially counteract the change.
How does temperature affect equilibrium?
Increasing temperature favours the endothermic reaction, while decreasing temperature favours the exothermic reaction.
