The rate and extent of chemical change Flashcards
What are some examples of slow reactions?
- rusting of iron
- chemical weathering
What is an example of moderately sped reactions?
magnesium reacting with acid to produce a gentle stream of bubbles
What are some examples of fast reactions?
- burning
- explosions
What is activation energy?
the minimum amount of energy the particles need to react
What is the collision theory?
- collision frequency of reacting particles- more collisions the faster the reaction
- energy transferred during collision- particles have to collide with enough energy for the collision to be successful
What 4 factors does rate of reaction depend on?
- temperature
- concentration of solution or pressure of gas
- surface area
- presence of catalyst
Why does increasing the surface area increase the rate of reaction?
- If one of the reactants is a solid, then breaking it up into smaller pieces will increase it’s surface area to volume ratio
- for the small volume of the solid, the particles around it will have more area to work on- so there will be collisions more frequently.
What is meant when a system is at equilibrium?
The forward reaction will be going at the exact same rate as the backwards one
What does it mean if the equilibrium of a reaction lies to the right?
the concentration of products is greater than that of the reactants
What does it mean if the equilibrium of a reaction lies to the left?
the concentration of reactants is greater than that of the products
What is Le Chatelier’s Principle?
the idea that if you change the conditions of a reversible reaction at equilibrium, the system will try to counteract the change
How does temperature effect reversible reactions?
-if you decrease the temperature, the reaction will move in the exothermic direction to produce more heat. This means you will get more products for the exothermic reaction and less for the endothermic reaction. Vice versa if the temperature increases.
How does pressure effect reversible reactions?
- only involves gases
- if you increase the pressure, the equilibrium tries to reduce it- it moves in the direction where there are fewer molecules of gas
- vice versa with decreasing pressure
How does concentration effect reversible reactions?
- If you change the concentration of either the reactant or the products, the system will no longer be at equilibrium
- the system needs to bring itself back to equilibrium SO if you increase the concentration of reactants the system tried to decrease it by making more products vice versa