exothermic Flashcards
(17 cards)
What is an exothermic reaction
a chemical reaction that releases heat energy to its surroundings, this makes the surroundings HOTTER.
what is a endothermic reaction?
A chemical reaction that absorbs the heat energy from its surroundings, making the surroundings temperature to decrease.
examples of exothermic reactions?
Combustion, respiration in cells, neutralisation,
rusting, hand warmers, oxidation
Examples of endothermic reactions?
Photosynthesis , thermal decomposition , evaporation of water
, electrolysis of water
What is activation energy?
Amount of energy that is required for reactants to absorb to create a chemical reaction
in a endothermic reaction profile, why is the products higher?
the PRODUCTS are on a higher energy level than the REACTANTS.
difference in height shows the overall energy change.
What is thermal decomposition?
when a substance breaks down into smaller parts because it is heated, it’s a endothermic reaction that ABSORBS energy.
methods to show energy changes?
Reaction profiles, they show how energy changes over the course of the reaction.
what should be used when containing the solution when investigating energy change irl?
a polystyrene cup - provides insulation and reduces heat loss
thermometer - measure temp changes
Timer - measuring the duration
What are ions?
Ions are made when ELECTRONS are transferred.
What happens when atoms lose/gain electrons?
they form ions, they do this to achieve a full OUTER SHELL.
what happens when metal ions form?
They lose electrons from outer shell, which creates POSITIVE ions
What happens when non-metal ions form?
they gain ELECTRONS, and form NEGATIVE ions
true or false, elements in the same group have the same number of OUTER ELECTRONS
True
true or false, non-metals always form negative ions
True, they have high electronegativity and low ionisation energy.
Why do simple ions have noble gas electronic structures?
Because they gain/lose electrons to achieve a stable arrangement of electrons LIKE a noble gas.
What is an example of a simple ion that has adapted to a noble gas structure?
cations (+ positive ions) like sodium (Na+) loses 1 electron to be stable
anions (- negative ions) like chloride (Cl-) gains 1 electron to be stable
