Chemistry C7 - Energy changes Flashcards
What is conservation of energy?
The theory that energy cannot be either created or destroyed.
What is an exothermic reaction?
A reaction that transfers energy to the surroundings
How can you tell an exothermic reaction has occurred?
The temperature of the surroundings will increase
What is an endothermic reaction?
A reaction that takes in energy from its surroundings
How can you tell an endothermic reaction has occurred?
The temperature of the surroundings will decrease
What is activation energy?
The energy required before a reaction can start.
What must happen for a chemical reaction to occur?
Bonds in reactants must break and bonds in products must form.
What type of process is bond breaking?
Endothermic – it requires energy
What type of process is bond making?
Exothermic-it releases energy.
What decides if a reaction is endothermic or exothermic?
Whether more energy is released from making bonds or taken in whilst breaking them.
How do cells release electricity?
They contain chemical that react.
How can a simple cell be produced?
By placing two different metals in an electrolyte
What does a battery consist of?
Two or more cells connected in series.
Why do batteries stop working?
A reactant runs out.
Why can some batteries be recharged?
They use reactions that are reversible.
Draw a reaction profile diagram for an exothermic reaction:
Draw a reaction profile diagram for an exothermic reaction:
