Chem test 3 study deck Flashcards
What is the 1st law of thermodynamics?
the law of conservation of energy
What does the law of conservation of energy state?
Energy can be neither created nor destroyed
What is the mathematical equation for the 1st law of thermodynamics?
delta E universe= delta E sys +delta E surr=0
________ is the part of the universe that is the focus of the thermodynamic study
system
A system can be
1.
2,
3.
Isolated
Open
closed
_______ is everything in the universe that is not of the system
surroundings
The ______ is system+ surroundings
universe
_____ systems exchange both energy and matter
open
______ systems exchange only energy
closed
_______ systems do not exchange energy and matter
isolated
______ and ______ functions describe how properties of a system depend on changes
path and state
_____ functions are properties that depend only on current state of a system and not on the path taken to reach that state
state
enthalpy, entropy, pressure, temperature, and volume are _____ functions
state
______ functions are properties that depend on the specific path taken to reach a particular state
path
heat (q) and work (w) are _____ functions
path
What is the equation for energy change to the system?
Delta E= q+w
______ is energy transferred between objects because of difference in their temperatures
heat
_____ is heat leaving the system
exothermic
______ is done when a force (f) moves and object through a distance (d)
work
What are the two equations for work?
w= F(d)
w= -Pdelta V
work done by the system is energy _____ by the system
lost
work done by chem system is ______ of gas
expansion
solid to gas is _____
endothermic
liquid to gas is ____
endothermic
solid to liquid is _____
endothermic
gas to solid is _____
exothermic
gas to liquid is _____
exothermic
liquid to solid is _____
exothermic
______ _____ ______ is energy required to change amount of something by 1 degree K
specific heat capacity
What is the equation for calorimetry?
q=mcdeltaT
____ is the heat absorbed or given off by the system
q
If the system has two or more components how do you find the energy?
delta E= m1c1deltaT +m2+c2Delta T ….
______ is the amount of heat necessary to raise the temperature of 1 g of water 1 C
calorie
_______ J = 1 cal
4.184 J
What is the equation for enthalpy?
delta H= delta sys+ P delta V
q(p) - heat to _____
system
exothermic has ______ delta H
negative
endothermic has ______ delta H
positive
(delta r) H, the subscript r denotes ___ _____ of ____
per mole of reaction
What are the three ways to calculate delta r H
- Hess’s Law
- Enthalpies of formation
- Bond dissociation enthalpies
If a reaction can be broken into a series of steps delta H for the overall reaction will be equal to the sum of the ______ changes for the individual steps
enthalpy
_______ ____: use of reactions with known enthalpies to find enthalpy of unknown reaction
Hess’s law
If reaction is reversed, the enthalpy of reaction changes _____
sign
If coefficients in a balanced reation are multiplied by an value, the value of ______ is multiplied by the same value
delta H
Magnitude of delta H is _______ proportional to the quantities of reactants and products in a reaction
directly
pure elements in their most stable form at 25 C and standard sate conditions are assigned a delt Hf value of ____
zero
What are the standard state conditions for delta H
1 bar pressure, (1 atm)
1 M concentration
25 C
What is the equation for delta H r with delta Hf
[ v[ delta Hf (prod)- [ Vr delta H f (react)
most thermodynamic quantities depend to some degree on _____
temperture
enthalpy changes as changes in ____ strengths
bond
Breaking bonds _____ energy
requires
Bond dissociation enthalpies are only applicable for reactions in which all components are _____
gases
all gas-phase DH values are _____
positive
What is the equation for bond dissociation enthalpies?
dletar H= [ DH react+ DH(prod)
______ the heat needed to convert 1 mole of a solid at its melting point to 1 mole of liquid
molar heat of fusion
what is the equation for molar heat of fusion
q=ndeltaH fus