W7 Flashcards
Calculating gibbs with multiple gases
G = NaUa + NbUb
Where Ua and Ub are the chemical potentials of gases A and B
High chem potential
Addition causes free energy to increase resulting in a high free energy for the system
Low chem potential
Addition causes free energy to increase only slightly
Higher free energy means
Higher driver for spontaneous reaction
Remember everything tries to loose its free energy to surroundings
When a reaction occurs the system goes in what direction
Direction of high chem potential to low until net potentials of products and reactanats balance
Equi constant equation
K = [C]c[D]d / [A]a[B]b
Le chateliers principle
When external change is made to a system the system responds to oppose the change. If OH is added to the left the equi will move to the right
3mols on the left and 2 mols on right, the forward reaction is favoured so equi moves right
More reactants the equi moves right
Moe products the equi moves left
If T increases
Equi move in endo direction to produce heat
If T decreases
Equi move in exo direction to release hear
If P increases
Equi move to side which would reduce pressure = side with less mols
If P decrease
Equi move to side which would increase pressure = side with more mols
Gibbs using equi constant equation
△G = -RT ln(k)
Van hoff equaiton
Derived from △G=-RTln(k) and △G= △H-T△S to give:
ln(k) = (△S/R) - (△H / RT)
Molarity
Number of moles of solute in 1 L of solution
Molality
Number of moles of solute in 1000 g of solvent
Mole fraction
Number of moles of the solute divided by the total number of moles of the solute plus the solvent
Raoults law
The parcel pressure of a substance in a liquid mix is proportional to its more fraction
Pn = XnPn*
Pi* is the vapour pressure of the pure substance
So first solution with two components it would be :
P = X1P1* + X2P2*
What is vapour pressure?
Pressure exerted by vapour on the surface of a liquid at a given temperature
Higher the temperature equals
The greater the vape pressure
Lower the temperature equals
Lower the vapour pressure
What is P^0
What is P1^0
What is P1
The vapour pressure of one liquid
The vapour pressure of pure liquid one
The partial vapour pressure of liquid one solution
What is partial vapour pressure directly proportional to?
Mole Fraction
P1 ∝ X1
How to calculate the mole fraction (X1)
Number of moles of liquid1 / (number of moles of liquid 1+2)
Partial vapour pressure and constant K equation
P1 ∝ X1
Remove ∝
P1 = KX1 (equation 1)
Raoults law versus Dalton law
Raoults tells us partial pressures where Dalton tells us total vapour pressure
Molality equation
m = moles of solute / kilograms of solvent
Capital M is molarity
Colligative properties
Solution behaves differently to pure solvent as there are particles of solute to interfere with physical processes
A solution will display certain colligative properties that depend only on the concentration of solute and not the chemical identity of the particles
Adding solute to solvent will change the following
VP lower
BP elevate
FP depress
Where do solid particles interfere?
Interfere with solvent activity at the boundary between gas and liquid phases
Particles on the surface can go into the gas phase and determines the vapour pressure solute particles on the surface can prevent it so pressure decreases
Hypotonic isotonic and hypotonic
Hypertonic is two arrows leaving the cell so shrivel
Isotonic is one arrow entering and one arrow leaving so is perfect
Hypotonic is two arrows entering so swells
How to describe change
We compare the initial and final values
△P = Pf - Pi
Reaction rate equation
m = △C / △T
Constant function and linear function equation
Y = b
Y = mx+b
What is a derivative?
A function that gives a slope at an X value i.e. F(X) = 8, the value on the graph will have a line that is straight at Y = 8 with a slope of zero
Power rule of (d/dx) X^n
= nX ^ n-1
So (d/dx) X^3 = 3X^3-1 = 3X^2
Constant multiple rule
d/dx [C x F(X)] = C x d/dx [F(X)]
So
d/dx (4X^7) = 4 x d/dx (X^7) = 4 x 7X^7-1 = 4 x 7X^6 = 28X^6
What is d/dx [lnx]
1/x
What is d/dx [lnx^3]
3/x
What is d/dx [ln(x^2+4)]
2x / (x^2+4)
What is integral of 4dx
bdx = bx+c
4dx = 4x+c
What is integral of 5x dx
mx dx = 1/2 mx^2 +c
5x dx = 1/2 5x^2+c
What is the vapour pressure of pure water?
760 torr
