Chapter 10 Reaction rates & equilibrium Flashcards
What is the equation for rate of reaction, With concentration?
Rate of reaction = Change in concentration / Time
What are the four main factors that change rate of reaction?
- Concentration
- Temperature
- Use of a catalyst
- Surface area of solid reactants
What is the collision theory?
States that two reacting particles must collide for a reaction to occur
What two conditions must be met for a collision to be effective?
- The particles collide with the correct orientation
- The particles have sufficient energy to overcome the activition energy barrier of the reaction
What are the effects of increasing concentration on rate of reaction?
An increase in concentration increases the number of particles in the same volume so the particles are closer together and have a higher freqency of collisions
What are the effects of increasing pressure on rate of reaction?
As pressure increases, the concentration of the gas molecules increases as the same number of gas molecules occupy a smaller volume. The gas molecules are closer together and collide more frequently leading to mroe effective collisions
What is a catalyst?
A substance that changes the rate of a chemical reaction without undergoing any permanent change itself
What is a homogeneous catalyst?
A catalyst in the same physical state as the reactants
How does a homogeneous catalyst work?
The catalyst reacts with the reactants to form an intermediate
The intermediate then breaks down to give the product
The catalyst is regenerated
What is a hetrogeneous catalyst?
A catalyst in a different physical state from the reactants
How does a hetrogeneous catalyst work?
Reactant molecules are adsorbed onto the surface of the catalyst where the reaction takes palce
After the reaction, the product molecules leave the surface of the catalyst by desoprtion
What are reversible reactions?
Reactions that take place in both ‘forward’ and ‘reverse’ directions
What is a closed system?
A system isolated from its surroudings, so the temperature,pressure and concentrations of reactants and products are unaffected by outside influences
What does the position of equilibrium indicate?
The extent of the reaction
What is Le Chatelier’s principle?
When a system in equilbrium is subjected to an external change the system readjusts itself to minimise the effect of that change
