+++++ Energy In Chemical Reactions Flashcards
What is an exothermic reaction
An exothermic reaction is one that gives out heat
What is observed in an exothermic reaction
A temperature rise is observed when an exothermic reaction takes place
Example of an exothermic reaction
The burning of coal or natural gas
What is an endothermic reaction
An endothermic reaction is one that takes in heat
What is observed in an endothermic reaction
A temperature drop
Example of an endothermic reaction
Reaction of sherbet with water or photosynthesis
What happens during photosynthesis
Plants take in energy from the sun and cause carbon dioxide and water to change into glucose and oxygen
what is more common
Exo or endothermic
Exothermic
What is an effective collision
It is one that results in the formation of products
What is the collision theory
theoryused to predict the rates of chemical reactions, particularly for gases
For a reaction to occur, what must happen
The reacting particles must collide with each other
What is activation energy
It is the minimum energy that colliding particles must have for a reaction to occur, that is, the minimum energy required for effective collisions between particles to take place
How do we explain why reactions are faster at higher temperatures
There is an increased number of collisions since the molecules have more energy.
More of the collisions have enough energy for the reaction to occur.
What is the diagram used to show an exothermic or endothermic reaction
An energy profile diagram or a reaction profile diagram
What is an energy profile diagram
It is a graph that shows the change in energy of a chemical reaction with time as the reaction takes place
Do exothermic reactions products have more or less energy than the reactants
They have less energy than the reactants
Do endothermic reactions products have more or less energy than the reactants
They have more energy than the reactants
How is the energy given out represented by
Delta H
Why does particle size affect the rate of reaction
The smaller the particle the more surface area is exposed causing more collisions
The number of collisions that are effective will increase because of this
How does the concentration affect the rate of reaction
The molecules are crowded closer together. Therefore there number of effective collisions will increase
The rate of reaction will also increase
Why do catalysts affect the rate of reaction
A catalyst works by providing an alternative route for the reaction to occur
