Energy Changes & Combustion Flashcards
What happens whenever a chemical reaction occurs?
A change in energy.
What is an exothermic reaction?
One that gives out heat energy to the surroundings, usually in the form of heat and shown by a rise in temperature by the surroundings.
What is an endothermic reaction?
One that takes in energy from the surroundings, usually in the form of heat and shown by a fall in temperature of the surroundings.
What is the enthalpy change?
The overall change in a reaction.
What values can a enthalpy reaction have?
a positive or negative value
What value would an exothermic reaction be?
negative value, as it GIVES OUT energy.
What value would an endothermic reaction be?
positive value, as it TAKES IN energy.
What is a combustion reaction?
When something reacts with oxygen to release energy.
Why are hydrocarbons and alcohols great fuels?
Because the combustion reactions that happen when you burn them in oxygen gives lots of energy - making them exothermic.
What happens when you burn hydrocarbons or alcohols in a plenty of oxygen?
The only prodcuts are carbon dioxide and water - this is a COMPLETE COMBUSTION.
What happens when different fuels burn?
They all release different amounts of energy.
