Physical Chemistry

Atmospheric pressure

It is the pressure exerted by Earth’s atmosphere, and is measured using a barometer.

The remaining weight of mercury is the atomospheric pressure (760mmHg)

This is a barometer which consists of a long glass tube filled with mercury. If it is inverted in a dish filled with mercury, as in the picture, some of the mercury will flow out. How is atmospheric preesure determined?

Manometer

It is a device used to measure the pressure of gases other than the atmosphere

The gas pressure will cause the liquid to move. The vertical height difference (mm) between the liquids exposed to the atmosphere and that of a substance whose pressure is unknown, is the pressure.

This is a graphical representation of a manometer. How is pressure determined?

P_A = x_AP_tot

What is the formula for the partial pressure according to Dalton’s law?

Gas Diffusion

It is a motion of the gas when gas particles spread out from a place where there a lot of them to a place where there are fewer, until they are evely mixed.

What is the formula for Graham’s Law of relative rates that is applicable for gas diffusion/effusion?

What is the formula for calculating root-mean-square speed?

high; low

Gases are most ideal at ____ (high, low) temperature and ____ (high, low) pressure.

Compressibility factor, z, is the ratio of molar volume of the gas to the molar volume of ideal gas (Z=Vm/Vm°)

What is compressibility factor?

(a) ideal gas

(b) repulsive forces

(c) attractive forces

What do these compressibility factors denote: (a) Z=1, (b) Z>1, and (c) Z<1

Tb = a/Rb

What is the formula for Boyle temperature?

What are the equations for the ff. real gases:

• Van der waals

• Berthelot

• Dieterici

• Virial

dU = dq + dw
q = mC∆T
w = –P_extdV

Formula for (a) ∆U, (b) q, and (c) w

(I) ∆H = ∆U + ∆PV

∆H = ∆U + ∆nRT
(II) ∆H ≈ ∆U

What is the formula for enthalpy that shows relationship with ∆U? How about for condensed phase?

Latent Heat

Latent or Sensible Heat: It is the energy that is absorbed or released during a phase change.

Sensible Heat

Latent or Sensible Heat: It is the energy that is used to raise the temperature of a substance.

(a) volume; (b) pressure

What is constant in (a) bomb calorimeter, and (b) coffee-cup calorimeter?

Formula for Joule-Thomson coefficient, µ_J, in terms of Cp and Cv

∆U = ∆H = 0
q = –w
q = –nRTln(V₂/V₁) = –nRTln(P₁/P₂)

State the important formulas for First Law of Thermodynamics in reversible isothermal processes.

q = 0
∆U = w

State the important formulas for First Law of Thermodynamics in reversible adiabatic processes.

In an adiabatic process, state the formulas showing the relationship of P, V, and T.

q = w = ∆U = ∆H = 0

State the important formulas for First Law of Thermodynamics in adiabatic expansion of gas into a vacuum.

746

1 horsepower = ____ W

∆_cH_T° = ∆_fH°_products - ∆_fH°_reactants

Standard Enthalpy of Combustion

∆H°_T2 – ∆H°_T1 = ∆Cp°∆T

Kirchoff’s Equation

∆S°_T2 – ∆S°_T1 = ∆Cp°ln[T₂/T₁]

Temperature Dependence of Reaction’s Entropy

1 bar

What is the standard-state pressure?

∆_rU° = –C_K+P∆T

What is the formula for standard internal energy of a reaction performed in an adiabatic bomb calorimeter?

–2801kJ/mol

∆U°₂₉₈ of glucose was found to be –2801kJ/mol. Find ∆H°₂₉₈ of glucose.

You can’t build a cyclic engine that can convert to useful work with 100% efficiency.

What does second law states?

Formula of efficiency in (a) heat engine, and in (b) refrigerator

dS = 0

Formula of entropy for cyclic process

dS = 0

Formula of entropy for reversible adiabatic process

dS = dq/T

Formula of entropy for reversible isothermal process

dS = dH/T

Formula of entropy for reversible phase change at constant T and P

Formula of entropy for constant pressure heating or cooling without phase change

Formula of entropy for reversible change of state in perfect gas

Formula of entropy for adiabatic expansion in vacuum of a perfect gas

Formula for entropy for mixtures

The entropy of a perfect crystal at 0K is zero.

What does the third law of thermodynamics states?

∆H	∆S
-	+	Spontaneous at all T

∆H	∆S
-	+

∆H	∆S
+	-	Nonspontaneous at all T

∆H	∆S
+	-

∆H	∆S
+	+	Spontaneous at high temperature

∆H	∆S
+	+

∆H	∆S
+	-	Spontaneous at low temperature

∆H	∆S
-	-

(a) Diamond
(b) D₂

Which of these substances have higher entropy?
(a) Graphite and Diamond
(b) H₂ and D₂

Gibbs free energy measures the maximum work that can be done by the system, while helmholtz free energy measures the useful work.

What is the difference between Gibbs and Helmholtz Free Energy?

Define the Gibbs equations for dU, dH, dA, dG.

Formula for isobaric thermal expansivity (a), isothermal compressibility (k), and a/k

Define volume dependence of U using Maxwell Relations.

Define pressure dependence of H using Maxwell Relations.

Define heat capacity difference using maxwell relations (Cp-Cv).

What is (∂U/∂V)_T for (a) ideal and (b) Van der Waals gas?

When can we say that phase equilibrium is achieved, in terms of µ, in the liquid-vapor phase equilibrium where substance gets transferred from gas to liquid?

What is the Clapeyron formula for condensed phase transitions?

What is the Clapeyron formula for transitions involving vapor phase?

What is the formula for Gibbs phase rule?

F=1 because temperature is held constant

What is the degrees of freedom for the ff. reaction:
CO_2(g) + H₂O_(l) = H₂CO_3(aq) at 20°C

In a completely miscible liquid system (two-component system) without reactions, what components are present in each portion of this diagram?

Eutectic Point

It is the specific temperature and composition at which a mixture of two or more substances solidifies or melts into two distinct solid phases simultaneously, and this is the lowest possible melting point for the mixture.

There are two eutectic points where below this point, there is the congruently melting compound (AB_2(s)→AB_2(l)).

What do the phase diagram of a two-component system where there occurs a eutectic reaction look like?

In a peritectic reaction, the produces a different solid phase upon cooling (AB_2(s)=B_(s)+melt).

What do the phase diagram of a two-component system where there occurs a peritectic reaction look like?

Stokes-Rozeboom Diagram

It is the diagram used for three-component systems

Binodal curves are positioned in the area of partially miscible liquids and there exist maximum number of phases.

a.

b.

c.

In a multicomponent system, where do binodal curves positioned and how many phases are there inside of it for:

a. Two completely miscible liquids and 1 partially miscible
b. Two partially miscible and 1 completely miscible liquids
c. All are partially miscible

Formula for Dalton’s Law of Partial Pressure

Vapor pressure

It is the pressure that measures of how easily molecules can escape from liquid into vapor phase.

Formula for partial pressure according to Raoult’s Law

Formula for Combination of Dalton and Raoult’s Law

What are the components in this vapor pressure-composition phase diagram?

Positive Deviation: The mixture has a higher vapor pressure than its pure components

Negative Deviation: The mixture has a lower vapor pressure than its pure components

What does the positive and negative deviation in Raoult’s Law mean?

Azeotrope

What is created in the intersection point in a phase diagram the deviated Raoult’s law?

Rhombic Sulfur, Monoclinic Sulfur, Liquid and Vapor Sulfur

What are the 4 phases of Sulfur?