Energy changes Flashcards
What is an exothermic reaction? Give an example
energy is given off in the form of heat or light.
making an ice cube
burning a candle
What is an endothermic reaction? Give an example
energy is gained in the form of heat or light
melting an ice cube
What are everyday uses of exothermic and endothermic reactions?
instant hot and cold packs used to treat sporting injuries
What must occur for particles to react?
activation energy
What is the activation energy?
the minimum amount of energy required to activate atoms for particles to react
What can the reaction profiles be used to show?
Energies of reactants and products, the activation energy and the overall energy charge of a reaction
What is a reaction profile and how can you make one?
diagram showing the change in chemical potential energy
exothermic reactants higher than products
endothermic reactants lower than products
What must be supplied during a chemical reaction to break bonds?
Energy
How do you calculate the energy transferred in chemical reactions?
Energy in - energy out
What do cells contain which react to produce electricity?
Chemicals
How can a simple cell be made?
connecting two different metals in contact with an electrolyte
What are some factors that affect the voltage produced by a cell?
what the electrodes are made from and the substance used as the electrolyte
What is a battery?
device that stores chemical energy and converts it to electricity
What is the difference between rechargeable and nonrechargeable cells?
rechargeable cells can be reused after charging once they have been completely discharged
non rechargeable cells can only be fully discharged once
What are alkaline batteries?
non-rechargeable
