C7 Flashcards
What is an exothermic reaction ?
A reaction that transfers energy from the reacting chemicals to their surroundings .
What can you measure in an exothermic reaction ?
You can measure a rise in temperature in the surroundings as the reaction happens .
What is an endothermic reaction ?
A reaction that transfers energy from the surroundings to the reacting chemicals .
What happens to the temperature in an endothermic reaction ?
These reactions cause a fall in temperature .
What is an example of an exothermic reaction ?
The burning of fuels such as the combustion of methane gas
What reaction is more common , an endothermic or exothermic reaction ?
Exothermic
What is the reaction used to transfer energy to the food or drink is usually :
Calcium oxide + water - calcium hydroxide
What can endothermic processes be used for ?
To cool things down
What can exothermic reactions be used for ?
Heating things up
How can we find out more of whats happening in a particular reaction ?
By looking at a reaction profile
What does a reaction profile show you ?
These diagrams show the relative amounts of energy contained in the reactants and the products .
What shows the course of the reaction in a reaction profile ?
A curved line
For an exothermic reaction where does the line start on a reaction profile ? And what does this line represent
Towards the top and it represents the reactants
In an exothermic reaction , what way does the curved line go ?
Downwards
What does the end line after the curved one represent on a reaction profile ?
The products
In an endothermic reaction where does the reactants line start ?
At the bottom
In an endothermic reaction does the line curve straight upwards ?
Yes
What do you have to draw next to the curved line in a reaction profile ?
Whether energy is being released or absorbed
What is activation energy ?
The energy needed to start of the reaction
Which reaction is bond breaking ?
Endothermic
Which reaction is making bonds ?
Exothermic
What is bond energy ?
The energy needed to break the bond between two atoms .
How do you calculate the energy change for a chemical reaction ?
Energy change = energy taken in - energy given out
How do you calculate the rate of a reaction ?
Rate = amount of reactant used / time taken
