Unit 5- Energy Changes Flashcards
What is an Exothermic reaction
One which transfers energy to the surroundings usually by heating. This is shown as a rise in temperature
What is an endothermic reaction
Reactions which takes energy in from the surroundings, this is shown as a fall in temperature
Example of Exothermic reaction
Neutralisation, combustion
Uses of Exothermic reactions
Hand warmers- use the Exothermic oxidation of iron in air to release energy
Self heating cans
Example of endothermic reaction
Thermal decomposition
Uses of endothermic reactions
Used in sport injury packs, allows pack to become instantly cooler without having to be put in freezer
What is a fuel cell
Electrical cell that produces electricity using fuel and oxygen
Uses of fuel cells
Used in vehicles- don’t produce nasty pollutants, however uses a lot of energy
What is equilibrium
Rate of forward and background reactions are equal in a closed system where nothing is added or taken away
How does changing the pressure affect equilibrium
In a reaction involving gases, if pressure is increased, equilibrium moves in the direction of fewer molecules of gas
How does concentration affect equilibrium
In reaction involving solution, if concentration of a solute is increased equilibrium moves in the direction away from this solute
How does changing temperature effect Exothermic reaction
Temperature raised means yield decreased, temperature lowered means yield increased
How does changing temperature affect endothermic reaction
Temperature raised means yield increases, temperature lowered means yield decreases
