C2.5 Chemical Reactions Flashcards
What is an endothermic reaction?
A reaction that takes in heat from the surrounding environment
What is a combustion reaction?
Exothermic
Why is an exothermic reaction exothermic?
More energy is released making new bonds than is needed to break the bonds of the reactants
Why is an endothermic reaction endothermic?
Less energy is released making new bonds than is needed to break the bonds of the reactants
What factors affect rates of reaction?
Solution concentration
Temperature
Surface area
How does temperature affect the rate of reaction?
The particles move faster so they are more likely to collide more, and the success chance of a collision will be greater, so the rate of reaction will be increased
How does concentration affect rate of reaction?
The more concentrated a solution is, the more solute particles there are in am volume so the particles are more likely to collide and this increases the rate of reaction
How does surface area affect the rate of reaction?
As only the surface particles on a reactant can be involved in a reaction, increasing the surface area exposes more particles increases the number of collisions and so the rate of reaction
What is a catalyst?
A chemical that speeds up a reaction without being used up itself
What two things do catalysts do?
Lower the activation energy for the reaction
Speed it up
What do catalytic converters in cars do?
Combine Carbon monoxide and unburnt petrol with oxygen to form carbon dioxide and water vapour
What is an exothermic reaction?
A reaction that gives off heat to the surrounding environment
Why is the Catalyst spread out thinly over a honeycomb structure in a catalytic converter?
To give it a larger surface area
