1/53
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
Define Thermochemistry
the study of energy changes that occur during a chemical reaction and changes in the state
Define energy
the ability to work or produce heat
Define temperature
a measure of the amount of kinetic energy an object/substance has
measured in C or K
Define Heat
thermal energy- energy that transfers from one object to another
measured in joules (q)
transfers because of difference in temperature
always flows from a warmer temperature to a cooler object
Which would have more thermal energy?
The one with more of a substance because it has more to transfer to
Potential Energy
stored energy that could be used
- gravitational: ball on top of a hill
- elastic: stretching a rubber band
Kinetic energy
the motion of an object
KE= 1/2 mv^2
Law of conservation of energy
energy can neither be created or destroyed
chemical potential energy
energy thats stored in the chemical bonds of a substance
determined by types of atoms and their arrangement
System
the reaction or focus
surroundings
everything around the reaction
ie. container, room, etc.
universe
system and surroundings
define exothermic process
heat is released into the surroundings by the system
exo = exit
-q
define endothermic process
heat is absorbed from the surroundings by the system
endo = in
+q
what are the 2 common units for energy?
joules
calories
how many joules are in 1 calorie?
4.184 J = 1 calorie
How many calories in 4.184 J?
1 calorie = 4.184 J
How many calories are in 1 kilo calorie?
1000 calories = 1 kilo calorie
How many calories are in 1000 calories?
1 kilo calorie = 1000 calories
define heat capacity
amount of heat needed to increase the temperature of an object by 1'C
heat capacity depends on:
mass of an object
chemical composition of the object
define specific heat capacity
amount of heat needed to raise the temperature of 1g of a substance by 1'C
specific heat capacity of water
4.184 J/g'C
define molar heat capacity
amount of heat needed to raise the temperature of 1 mole of a substance by 1'C
what does each letter represent?
q=MCAT
q- heat
m- mass
c- specific heat
AT- change in temperature (final - initial)
what does -q mean compared to q?
-q heat loss
q heat gain
define calorimity
precise measurement of heat flow into and out a system
heat released by the system = ?
proved by law of conservation of energy
heat released by the system = heat absorbed by the surroundings
define calorimiter
insulated device used to measure absorption or release of heat
final temp of system = ?
final temp of system = final temp of the surrondings
define enthalpy
the heat constant of a system at constant pressure
AH
heat of a reaction
q system
q surrondings
q system
q system- AH
q surrondings- MCAT
q system- AH= -qsurrondings = -MCAT
negative enthaply means..
exothermic
positive enthalpy means...
endothermic
how to write enthaply in thermochemical equations
the heat change can be written as a reactant or product
define molar Heat of fusion
heta absorbed by one mole of a solid substance when it melts at a constant temperature
AH(fus)
define molar heat of solidification
heat lost by one mole of a liquid substance when it solidifies
AH(fus) = -AH (solid)
what does the graph look like when a phase change is occurring?
plateau
define molar heat of vaporization
heat energy required to boil one mole of a substance at its boiling point
AH(vap)
defien heat of a solution
enthaply change caused by dissolution of 1 mole of a substance
AH(sol)
heat_of_fusion_number
6.02
heat_of_vaporization_number
40.7
define_hess's_law
if_you_can_add_two_thermochemical_equations_to_produce_a_final_equation,_the_sum_of_the_enthaply_of_those_equals_the_enthalpy_of_the_others
condensing_steam
exo
burning_alcohol
exo
evaporating_alcohol
endo
baking_potatoes
endo
how_to_find_molar_heat_capacity
use the specific heat to convert it to moles with grams on top
triangle H means what?
heat of formation
standered conditions are what?
25'C and 1atm
difference between calorie, specific heat, and molar heat
specific heat- 1g
calorie- 1g of water
molar heat- 1 mole
condensing
exothermic
C
nutrional calories