Thermochemistry Flashcards
What is energy?
Capacity to do work
What is work?
Result of force acting through a distance
What is heat?
Flow of energy caused by tempersture difference
What is the system vs the surroundings?
What we chose to study
Everything the system can exchange energy with
How to convert joules to calories?
Multiply by 4.184
What is the internal energy (U) of a system?
Sum of kinetic and potential energies of all particles that compose the sustem
What is the equation for the change in internal energy?
delta U= q+w
What are the sign conventions for heat?
Positive system GAINS energy
Negative system LOSES energy
What are sign conventions for work?
Positive work done ON the system
Negative work done BY the system
What are sign conventions for delta U?
+ energy flows INTO the system
- energy flows OUT of system
Since nervy must be conserved -delta U of the system equals?
Delta U of surroundings
What is the equation for heat?
q=mcdeltaT
What is equation for molar heat capacity?
q=ncdeltaT
How can you solve a problem where equilibrium is reached between aluminum and water?
-qAl=qH2O
How can you calculate work?
w=-PdeltaV
How many liters are in a m^3
1000
What is the formula for work that uses the change in coefficients?
w=-detanRT
If the volume is constant what does the heat equal?
The change in internal energy
How can we relate the temperature change to the heat ablatives by a calorimeter?
qcal=CcaldeltaT
If no heat escapes the calorimeter the heat gained by the calorimeter equals?
The heat released by reaction
qcal=-qr
What is enthalpy?
Heat involved in reaction at constant pressure
What is the formula for the change in enthalpy?
deltaH=deltaU+PdeltaV
What does heat at constant pressure equal?
Change in enthalpy
The formula for enthalpy of reaction is?
DeltarH=DeltarU+deltanRT
What does delta n stand for?
change in coefficients of gases in balanced chemical equations
What does heat divided by moles equal?
DeltarH
In coffee cup calorimeters the heat gained by the solution is equal to?
Heat lost by reaction
qsol’n=-qr
In coffee cup calorimeters qr equals?
qr=qp=deltaH
What does bomb calorimeters measure?
Change in internal energy
What is coffee cup calorimeter used to determine?
deltarH
What is the formula for q solution?
Qsoln=msoln csoln deltaT
How can you find moles?
Dividing mass by molar mass or ideal gas law
How many joules are in one L bar?
100
