thermochemistry Flashcards
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what is true about exothermic reactions
decreasing enthalpy, increased stability, decreased energy
what is true about endothermic reactions
increasing enthalpy, decreased stability, increased energy
when the delta H is on the left handside of the equation what does that mean
energy is positive meaning it is endothermic
an exothermic diagram?
products are lower then reactants
an endothermic diagram?
products are higher then reactants
in q=mc(delta t). what does c=
Specifically in water
4.18
when asked about heat of reaction(or Ea)
calculate the top of the line subtracted by reactant.
what does BARF stand for
Break(bonds) absorbed(energy)/ release(energy) form(bonds)
what does exothermic reaction cause
increase in temp
Concentration calc
con=mole/dm^3
in order to go from cm3 to dm3
you must divide by 1000
when a question asks about diluting a certain volume, what eqation should be used
C1V1=C2V2
important thing about enthalpy of combustion:
is uauslly exothermic, delta H is negative, unit is kj mol^-1
source of error when measuring enthalpy changes
Heat loss to surrondings.
during enthalpy of solution what goes in instead of mass
volume of solution, if in dm3 get into cm3
Hess’s law
when formula is on opposite side switch number to opposite.
Highest kinetic energy?
Highest temperature
Delta h of graph
space from reactants to products
if exothermic -
if endothermic +
Where the reactants and products in the graph
Reactants left hand side products right hand side
enthalpy change equation things to do
when equation needs to be doubled, double the corresponding Delta H
flip equation, flip the sign of the delta H
Bond enthalpies
the energy needed to break one mole of bonds in gaseous molecules under standard conditions
enthalpy of solution what to use for m in q=mc delta T
use the volume of the two solutions and assume it as the mass
steps on how to solve for moles and q=mc delta T
- find the q=mc delta T, make sure to divide by 1000 in order to get into KJ
- find mol of the substance that is being burned(not water)
- than do KJ/Mol of the substance and make sure answer is Negative
the lower your energy is(what happens to stability
more stable
