C8 Revision For Mock Flashcards
Exothermic reaction
A reaction in which energy is transferred from the reacting substance to the surroundings
Endothermic reaction
A reaction in which energy is transferred to the reacting substance from their surroundings
Everyday use of exothermic reaction
Chemical Hand warmers and body warmers
Every day use of endothermic reaction
Chemical cold packs
What do chemical cold packs contain
Ammonium nitrate and water.When it dissolves it absorbs energy from it’s surroundings making them colder
What are chemical cold packs used for
Used as emergency treatment for sports treatment
Collision Energy
The reacting particles need to collide with each other with enough energy to cause a reaction to take place
Reaction Energy
The minimum amount of energy that particles need before they can react.
Factors affecting reaction rate (temperature)
Increasing the temperature makes the particles faster so they are more likely to collide with each other more often .
Factors affecting the rate of reaction (increase the concentration)
A concentrated solution will react faster than a dilute solution.This increases the number of reacting particles in the same space,so there is more chance they will collide
Factors affecting reaction rate (increase the surface area)
More particles are on the surface.By increasing the surface area there are more areas where reactants can collide with each other.
Catalyst
A catalyst is a chemical that helps a reaction to happen faster but is not used up itself.It lowers the amount of energy that particles need to collide with for a reaction to happen.
How do you find out the rate of reaction (measuring the decreasing mass of a reaction mixture)
As the reaction takes place,the mass of the reaction mixture decreases.You can measure and record the mass at regular time intervals.
How can you find out the rate of reaction (measuring the increasing volume of gas given off)
If you use a gas syringe to collect the gas you can measure the volume given off at time intervals.
How can you measure the rate of reaction(measuring the decreasing light passing through a solution)
Some reactions in solution makes a suspension of an insoluble solid(precipitate).This makes the solution go cloudy?You can use this to measure the rate at which the precipitation appears.
