Energy Transfer in Reactions Flashcards
What is an exothermic reaction?
A reaction that transfers energy to the surroundings, usually in the form of heat and usually shown by a rise in temperature.
Remember ‘ex’ for expel, as in it expels heat the surroundings.
What is an endothermic reaction?
A reaction that takes in energy from the surroundings, usually in the form of heat and usually shown by a fall in temperature.
What’s the best example of an exothermic reaction?
A combustion reaction, such as burning fuels, this gives off a lot of heat.
What type of reaction are neutralisation reactions?
Exothermic.
What type of reaction are oxidation reactions?
Mostly exothermic. For example, adding sodium to water produces heat, so it must be exothermic.
Name an everyday use of exothermic reactions.
Hand warmers use the exothermic oxidation of iron in aid (with a salt solution catalyst) to generate heat.
Which reaction is more common? Exothermic or endothermic?
Exothermic.
What’s the best example of an endothermic reaction?
Thermal decomposition.
Name an everyday use of an endothermic reaction.
Sports injury packs use endothermic reaction - they take in heat and the pack becomes very cold.
What type of reaction is a reversible reaction?
It can be both exothermic and endothermic #GOTCHA
If one reaction in a reversible reaction is exothermic, the other will be __________.
Endothermic.
In a reversible reaction, the energy absorbed by the endothermic reaction is equal the energy ________ by the exothermic reaction
Released.
What’s an example of a reversible reaction?
The thermal decomposition of hydrated copper sulfate, bloody mouthful and a half that like
Describe how the thermal decomposition of hydrated copper sulfate takes place.
Heat the hydrated copper(11) sulfate crystals.
This heat causes the water to evaporate and leaves behind a white anhydrous copper(11) sulfate powder.
THAT’S THE ENDOTHERMIC BIT, because heat was taken in by the copper sulfate.
If you add a couple of drops of water to the white powder, they react, producing heat and you get the blue hydrated crystals back.
