Test 4 Review Flashcards
stored energy
potential energy
feels hot
exothermic
releases heat
exothermic
delta H is positive
endothermic
absorbs heat
endothermic
feels cold
endothermic
reactants have heat
endothermic
heat is a product
exothermic
delta H is negative
exothermic
delta E symbolizes
internal energy
amount of heat required to melt 1 g of substance
heat of fusion
has more energy: boiling water v steam
steam
change in internal energy equation
delta E = Q + W (1st law of thermodynamics)
1 cal =
4.184 J
when work is done on system
positive
when entropy decreases
negative
gain in heat
positive
work is done by the system
negative
increase in entropy
negative
gain in heat
positive
under spontaneous conditions, if +delta S, then delta H is
negative (exothermic reaction)
enthalpy equation
delta H= delta E + PV
heat absorbed or released equation
Q = mc delta T
total amount of heat liberated from start of reaction to end
heat of reaction
has the word “heat” in the equation; look for delta H
thermochemical equation
released in crystallization; absorbed in fusion
heat
enthalpy of formation for any element in standard state
0 (zero)
amount of heat needed to vaporize
heat of vaporization
has the greatest entropy
gas
measure of disorder
entropy (2nd law of thermodynamics)
if when solving for delta H in a thermochemical equation and the answer is positive, the reaction is _________ and the word “heat” goes on the ________ side
endothermic
reactant
