C5 - chemical energetics (exo. & endo.) Flashcards
define exothermic reaction
-reaction that transfers heat energy to surrounding so temp. goes up
define endothermic reaction
-reaction that absorbs heat energy from the surrounding so temp. goes down
what must you do to break and make bonds
-break = absorb energy
-make = release energy
what type of reaction is neutralization reaction
exothermic
what happens to system & surr. in exo.
-system gives heat energy to surr.
-surr. heats up
what happens to system & surr. in exdo.
-surr. gives heat energy to system
-system. heats up
what do you call heat energy
-Enthalpy
-H
what is in the system
reactants & porducts
what is ( - ) ve & ( + ) ve
-( - ) ve = negative
-( + ) ve = positive
what is system & surr. in energy
-system = chemical energy
-surr. = heat energy
how do you draw a graph for exo. reaction
-Enthalpy on side
-reactants is higher than products
-reactants to products line is ΔH = -ve
-activation energy curve
-Ea is at peak of activation energy line to reactants line
-left is absorb E, right is release E
-arrows must touch
-ΔH is arrow down, Ea is arrow up
how do you draw a graph for endo. reaction
-Enthalpy on side
-products is higher than reactants
-reactants to products line is ΔH = +ve
-activation energy curve
-Ea is at peak of activation energy line to reactants line
-left is absorb E, right is release E
-arrows must touch
-both arrows face up
symbol for activation energy
-Ea
(a is subscript)
define Enthalpy change
-The difference between the energy required to break bonds and the energy released to make bonds
Explain an exothermic reaction in terms of bond breaking and bond making
-Less energy is absorbed to break bonds than energy released to make bonds
