Chemical Reactions Flashcards
What happens in a chemical reaction
Old bonds are broken and new ones are made
What happens in an exothermic reaction
The overall reaction gives out heat energy to the environment causing a rise in temperature
Bonds forming are exothermic
What is an endothermic reaction
A reaction which takes in energy from the surrounding causing a fall in temperature
Bonds breaking is endothermic
How is an endothermic reaction shown on a graph
Reactants are below the products
How is an exothermic reaction shown on a graph
The reactants are higher than the product because energy i s given out
How would you measure the temperature change of a reaction
Take the temperature of the reactants making sure they’re the same
Mix them in a polystyrene cup
Measure the temperature at the end of the reaction
What effects the rate of reaction
Temperature
Concentration
Catalyst
Surface area
What is a catalyst
A substance which changes the speed of the reaction without being used up in the reaction
How does a catalytic converter work
It is in motor vehicles in the exhaust pipe
It increases the rate that carbon monoxide and unburned fuels react with oxygen to become carbon dioxide and water
The catalyst has a large surface area and works best at high temperatures
How does a higher temperature increase the rate of reaction
The particles move quicker so there are more frequent collisions
How does a larger surface area increase the rate of reaction
The particles have more surface area to collide with so there are more frequent successful collisions
How does a higher contraction or pressure increase the rate of reaction
There are more particles of the reactant than the water so this makes collisions more likely and there will be more successful collisions
How does a catalyst increase the rate of reaction
A solid catalyst gives the particles something to stick to so the number of success collisions is increased because the particles need less energy to collide
How are faster collisions caused
By increasing the temperature this gives the particles more energy so the collisions are more successful in a shorter space of time
