thermodynamics :( Flashcards
all the names for heat
ΔH, enthalpy, Q
when does heat stop transferring
when temperatures are equal
if you touch a hot lightbulb what is system and surrounding
finger is system, lightbulb is surrounding
endothermic
system absorbes heat, +ΔH, reactants have higher energy than products
exothermic
system loses heat, -ΔH, reactants have lower energy than products
specific heat of water
4.18 JOULES
equation for heat
heat= (mass (g)) (C) (ΔT)
C=specific heat
ΔT= difference in heat in celsius
what is heat of fusion (ΔHfus)
energy required to melt a solid
what is heat of vaporization (ΔHvap)
energy required to vaporize liquid
what type of lattice does a solid have
crystalline (exceptions- glass, plastic, wax, and putty are amorphous)
in a heating curve graph, what does each line represent?
from origin, the diagonal lines are solid, liquid, gas.
Straight lines are melting and boiling point
what is the relationship between slope of a heating curve graph and specific heat
steeper slope= lower specific heat
melting and boiling point of H20
melting=0, boiling=100
steps for finding energy of phase changes
1) find heat of given phase
2) use stoich to go from given phase to the next one
3) find heat of the phase from part 2
4) repeat 1-2 if there’s another phase
when dealing with dissolution in thermo problems what do you do to the masses
add them
what is the ΔHf° of a pure element
0
equation for ΔH°rxn
ΔH°rxn= ΔHf° products- ΔHf° reactants
equation for ΔHrxn (bond energy)
ΔHrxn= ΔHreactants- ΔHproducts
what are the four ways to manipulate equations for Hess’ Law
flip, multiply, divide, Add
what is entropy
ΔS, or available microstates
what are the four ways to increase ΔS
1) increase molarity
2) increase volume
3) make a mixture
4) increase temp
equation of ΔS°system
=ΔS°products-ΔS°reactants Pure elements are NOT zero
equation of ΔS surroundings
ΔSsurr= -ΔH/T
T=temp in Kelvin
how to find kelvin
C° +273
