Topic 5; Energy Changes Flashcards
What is the conservation of energy principle?
Energy is conserved in chemical reactions.
Amount of energy at end of reaction is same as before reaction
What is an exothermic reaction (and examples)
Reaction where energy is transferred to surroundings so the surroundings temp increases
Combustion, oxidation reactions, neutralisation
Negative energy charge
What is an endothermic reaction? (Give examples)
Energy taken from surroundings so surroundings temp decreases
Thermal decomposition
Positive sign of energy change
What is activation energy?
Minimum amount of energy that particles need to react
What is a reaction profile?
Graph shows relative energies of reactant and products
What occurs in chemical reactions of terms of bond energies?
Energy supplied to break bonds and released to make bonds
Exothermic- energy released from forming bonds is greater than that needed to break bonds
Endothermic- energy needed to bream bonds greater than that released when making them
What is the equation to find energy change in terms of bond energies?
Energy of reaction= sum of broken bonds- sum of bonds made
What is a cell?
Two electrodes dipped in an electrolyte solution. Produces electricity from a chemical reaction
What is a battery?
Two or more cells connected in series
