The rate and Extent of Chemical Change Flashcards
the equation for the rate of reaction?
Amount of reactant used or amount of product formed
divided by
Time (seconds)
definition of turbidity?
cloudiness
When do chemical reactions occur?
when reacting particles collide with each other with sufficient energy
What is the activation energy?
the minimum amount of energy required to cause a reaction
What are the factors that affect the rate of reaction?
- Temperature
- concentration of reactants in solution
- pressure of reacting gases
- surface area of solid reactants
- the presence of catalysts
How does temperature affect the rate of reaction?
- high-temperature cause particles to move more quickly
- faster they move, the more energy they will have
- they will collide more often with greater energy so more collisions are successful
How does concentration and pressure affect the rate of reaction?
- at higher concentrations, the particles are crowded close together
- they collide more often = more successful collision
- Increasing pressure of reacting gases also increases the frequency of collisions
How does surface area affect the rate of reaction?
- small pieces of solid reactant have a large surface area
- more particles are exposed and available for collisions, so there are more collisions and faster reactions
What is a catalyst?
a substance that increases the rate of a chemical reaction without being used up in the process
Why are catalysts good?
- reduces the activation energy
- makes more collisions successful
- speeds up the reaction
- provides an alternate reaction pathway
- provides a surface for the molecules to attach to, increases the chance of collisions
How does increasing the rates of chemical reactions help the industry?
it reduces costs
What increases the frequency of collisions and therefore increases the rate of reaction?
Increasing :
- concentration of reactants in solution
- the pressure of reacting gases
- the surface area od solid reactants
What happens in a reversible reaction?
the products can react to produce the original reactants
Describe why the rate of the forward and backward reaction changes during reversible reactions
As reactants reactm their concentrations fall, so the forward reaction will slow down
as more products re made their concentrations rise, the backward reaction will speed uo
What is a closed system?
no reactants are added, no products are removed
What happens when a reversible reaction happens in a closed system?
- describe what a dynamic equilibrium is
a dynamic equilibrium is eventually achieved = the rate of the forward reaction is equal to the rate of the backward reaction
= concentrations of reactants and products have reached a balance and wont change
- this doesnt mean thte amounts of reactants and products are equal
What does it mean when the equilibrium lies to the left/right?
left = concentration of products are greater
right = concentration of reactants greater
What is le chatelier’s principle?
when conditions of a reaction in equilibrium are changed the reaction will do everything it can to counteract the change
What happens when the temperature of a system at equilibrium is increases or decreases in an EXOTHERMIC reaction?
and why
decrease = increased yield as the equilibrium will move in the exothermic direction to produce more heat
increase = will move to the endothermic reaction to reduce heat, reduces yield
What happens when the temperature of a system at equilibrium is increases or decreases in an ENDOTHERMIC reaction?
and why
increasing temp = increase yield as the equilibrium will move in the exothermic direction to produce less heat
decreasing = decreases yield, move to the exothermic direction to produce more heat.
What happens when pressure increases or decreases in an equilibrium reaction
- an increase in pressure causes the equilibrium position to shift towards the side with the smaller number of molecules
- a decrease in pressure causes the equilibrium position to shift towards the side with the larger number of molecules
What happens when concentration increases or decreases in an equilibrium reaction
If the concentration of one of the reactants or products is changed, the system is no longer at equilibrium and the concentrations of all the substances will change until equilibrium is reached again.
If the concentration of a reactant is increased, more products will be formed until equilibrium is reached again.
If the concentration of a product is decreased, more reactants will react until equilibrium is reached again.
