Physical Chemistry Flashcards
What is Boyles law
Relationship between pressure and volume
What is Boyles equation
P1V1=P2V2
What is Charles law
The relationship between volume and temperature
What is Charles equation
V1/T1=V2/T2
What is Avogadro’s law
The relationship between quantity and volume
What is Avogadro’s equation
V1/n1=V2/n2
What is Amontons law
The relationship between pressure and temperature
What is Amontons equation
P1/T1=P2/T2
What is the overall gas law equation
PV=nRT
What is the value of the R constant and what are the two common units used
8.314 JK-1Mol-1
Or
8.314 KPaLK-1Mol-1
What is Daltons law
The overall pressure is a sum of the partial pressures of the individual gases
To convert from 1 letre to m3 you must….
Divide by 1000
What does volatile mean
High boiling point
What is Grahams law
If P and T are constant, the rate of diffusion is inversely proportional to the square root of the gasses molar mass
What is effusion compared to diffusion
Effusion is the act of forcing a gas through a hole smaller than the mean path of partials. Diffusion is through a gap as big or bigger than the mean path of particals
What is a rigid thermodynamic system
A system that transfers heat but not work
What is an adiabatic thermodynamic system
A system that transfers work but not heat
What is the first law of thermodynamics
Energy is always conserved
What is the second law of thermodynamics
The entropy of the universe increases with a spontaneous reaction, if left alone a reaction will tend towards a higher probibility.
What is the third law of thermodynamics
That a pure crystalline solid at 0 Kalvin will have a delta S of zero
What is the equation demonstrating the first law of thermodynamics
deltaU=q+w (the sum of heat and work done)
What are state functions
‘Path independent’. It is determined by the initial and final states, not all the states to get to the final state.
What does PV mean and what is the equation
Pressure-volume work when gas undergoes a volume change
w=-PdeltaV
What is the opposite of state function
Path function
What is enthalpy in terms of internal energy and PV work
H=U+PV
What is the term for a reaction under constant pressure
Isobaric
What is Hess’s law
The sum of enthalpy changes for a whole reaction can be found using the enthalpy change of differing reaction steps as enthalpy is a state function and pathway independent
What is the term for a reaction under constant volume
Isochoric
Does enthalpy tabulated data have a zero value
No
What is deltaHf
This is the enthalpy change in formation of the species from its elements in their standard states
What is the deltaHf of elements in their most stable state. E.G. O2
Zero
What does deltaHr’ mean
This is a reactions enthalpy in standard conditions (1 bar pressure and 25 degrees). This allows for reactions to be comparable
What is the heat capacity refer to
The amount of heat required to heat to raise the temperature by 1 degree
What is the difference between heat capacity “C” and “c”
C is for molar, c is for grams (specific heat capacity)
What is the equation for c
c=q/(mxdeltaT)
What is the difference between K and Q
Q refers to the reaction quotient when the reaction is not in equilibrium. K refers to the reaction equilibrium when the reaction is at equilibrium, denoted with ‘e’ beside the concentrations
What can be used instead of concentration in the equilibrium constant if only gasses are involved
Partial pressures
What does it mean if K=Q
Equilibrium
What does it mean if Q>K
The concentration of products exceeds reactants
What does it mean if Q<K
The concentration of reactants exceeds the products
Does entropy have an absolute zero
Yes
What is a reversible reaction
- Conceptual
- Occurs over a infinite tine
- system and surroundings return to their original states
- always in equilibrium
- results in max work done by the system
Total entropy of a reaction is……..
deltaS surroundings+deltaSsystem
What is Gibbs free energy and its equation
Alternative function to entropy to predict natural direction. deltaG=deltaH-deltaSxT
Why is Gibbs preferred
You only have to know the data for the system
What is the reaction for deltaG in not standard state
deltaG=deltaG’+RTlnQ
What unit must be used for deltaG’
JMol-1
What 4 things affect kinetics of a reaction
- Physical states
- Concentration of reactants
- The temperature that the reaction occurs at
- The presence of a catalyst
What is the rate of reaction for 2A -> B
-1/2[A]/dT = [B]/dT
What is the unit for a zero order reaction
MolL-1s-1
What is the unit for a first law reaction
s-1
What is the unit for a second law reaction
LMol-1s-1
What is the unit for a third law reaction
L2Mol-2s-1
What is the cool feature of one of the rate order half life plot
First order reaction has a constant half life length
What is theorized to exist at the peak of the activation energy curve
A activator complex at the transition state
What does the Arrhenius equation involve
Links the rate constant to activation energy
What does A refer to in the Arrhenius equation
This is the preexponential factor, the frequency of collisions and the probibility the collisions are successful- slight dependance on temperature so only approx
What is a homogenous catalyst
A catalyst in the same phase as the reactants, is regenerated
What is a heterogenous catalyst
A catalyst that is of differing phase to the reactants, usually a metal that the reactants can react on, provides surface area for reactants to get into correct orientation
