2.4 Chemical Reactions
BELL RINGER [3 Minutes]
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AWL word
2.4 Chemical Reactions
MYP Biology: Chemical Reactions
2.4
ChemicalReactions
Reactions
Chemical
Transform Matter
• Chemical Reactions are processes that
transform matter by breaking and reforming
bonds in molecules and compounds.
– Reactants are the materials at the start of
the reaction that are changed during a
chemical reaction.
– Products are the materials at the
end of the reaction.
2.4
ChemicalReactions
Reactions
Chemical
REACTANTS
Transform Matter
PRODUCTS
2.4
ChemicalReactions
Reactions
Chemical
Transform Matter
2.4
ChemicalReactions
Reactions
Chemical
Transform Matter
Chemical reactions continue until they reach
EQUILIBRIUM, or a balanced state in which
the concentrations of reactants and products
no longer change.
CO2 + H2O
H2CO3
2.4
ChemicalReactions
Reactions
Chemical
Transform Matter
While matter is transformed in reactions, it is
never created or destroyed. The products
contain the same types and numbers of
atoms as the reactants. Scientists say that
matter is conserved in reactions.
2.4 Chemical Reactions
2.4
Chemical Reactions
Reactions
Absorb &
Release Energy
• Activation Energy is the amount of
energy that needs to be absorbed to start a
chemical reaction.
2.4
Chemical Reactions
Reactions
Absorb &
Release Energy
An EXOTHERMIC reaction is when more heat is
released from the reaction as a product. Heat
energy goes exits the reaction.
–Exo = Exit
2.4
Chemical Reactions
Reactions
Absorb &
Release Energy
An ENDOTHERMIC reaction is when more
heat is absorbed by the reaction as a reactant.
Heat energy goes into the reaction.
–Endo = Into
2.4
Chemical Reactions
Reactions
Absorb &
Release Energy
Activation
Energy (Ea)
REACTANTS
EXOTHERMIC
PRODUCTS
2.4
Chemical Reactions
Reactions
Absorb &
Release Energy
ENDOTHERMIC
2.4
Chemical
Reactions
Check
for Understanding…
• Reactants?
• Products?
• Endothermic or Exothermic?
A + B  AB + Heat
2.4
Chemical
Reactions
Check
for Understanding…
• Reactants?
• Products?
• Endothermic or Exothermic?
Heat + EF  F + E
2.4
Chemical
Reactions
Check
for Understanding…
• How much Activation Energy is needed?
2.4
Chemical
Reactions
Check
for Understanding…
• ENDOTHERMIC or EXOTHERMIC?
2.4
Chemical
Reactions
Check
for Understanding…
• ENDOTHERMIC or EXOTHERMIC?