Energy Change Flashcards
exothermic vs endothermic
surrounding temp rise/fall?
Exo -> rise
Endo -> fall
exo -> release energy to surrounding
endo -> absorb energy from surrounding
all chemical reactions involve…
energy change, surroundings
example exothermic reaction
in heat packs
MgO + Acid
endothermic vs exothermic
exo
1. heat energy given out, surroundings
2. temp, surroundings rise
3. energy change negative
4. form bonds
general types of exothermic reactions
- combustion, fuel (i.e. burn charcoal)
- rust iron, corrode metal
- respiration
- acid + alkali/carbonate/metal
all reactions mentioned above = form bond energy > break bond energy
endothermic reaction e.g.
dissolve ammonium salt
photosynthesis
film photography
energy lvl, profile diagram
H2o
used for wat?
for any (aq) soln. reaction i.e. aq sodium hydroxide
page 19 https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit?tab=t.0
reversible reaction
exothermic or endothermic?
forward: exothermic
backward: endothermic
define Triangle H
change in energy, reaction
how to find out reaction endo/exo w/ energy
depends, break/make bonds, need more energy?
i.e. 25kJ energy break O2 bond, 20 kJ energy bond O and N
- (break o2 bonds form O, O) 25kJ
minus
- (form O, N bonds for NO) 20kJ
= +5kJ
why req activation energy?
- must absorb energy, need break bond, reaction 2 start
similarity between exo, endothermic reactions
Activation energy is the same
when triangle H = 0, can reaction?
no
1. reaction did not occur
2. when delta H = 0, break and form same bonds
during exothermic reaction
when temp. peaks then drops what does it mean
https://docs.google.com/document/d/1Ep_FO9CxYSFbxmf3Zqg9mgm9NNyt2enpfMDr49gufrU/edit?tab=t.0
page 20
for energy change
writing abt breaking, form bond
specify bond
i.e. N-H
