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WorksheetsPhysical Chemistry Preboard Exam
Total questions: 100
Worksheet time: 50mins
Which has the smallest value of speed?
Root-mean-square
Most probable
Average
All speeds are equal.
Refer to Figure 3.1. Which of the following is TRUE?
T1 = T2
T1 > T2
T1 < T2
Cannot be determined
The kinetic theory of gases is based on all of the following assumptions EXCEPT
Gas consists of many particles of mass m, in continual motion.
At high pressures, Gas particles are difficult to compress.
Gas particles interact only by undergoing elastic collisions.
None of the above
An ideal gas has twice the molar volume of the other at the same temperature. What is their pressure ratio?
1 : 2
1 : 4
Cannot be determined
1 : 1/4
What is the molecular mass of a 4-gram gas if it occupies 11.2 L at 0°C and 0.25 atm?
16
20
48
32
Which of these three statements is TRUE?
I. The pressure exerted by each gas in a gas mixture (its partial pressure) is independent of the pressure exerted by all other gases present.
II. The total pressure exerted by a mixture of gases is the sum of the partial pressures of the component gases.
III. The amount of gas present in a mixture may be described by its partial pressure or its mole fraction.
III. Only
II. Only
All these statements are true
I. only
Which of the following effuses almost four times slower than hydrogen?
helium
Ethane
chlorine
water vapor
Which of the following is TRUE about the van der Waals 'a' and 'b'?
'b' corrects for the intermolecular interactions and 'a' for the included volume of the molecules
'b' corrects for the external pressure and 'a' for the internal pressure of the gas
'a' corrects for the intermolecular interactions and 'b' for the excluded volume of the molecules
'b' corrects for the free volume and 'a' for the intermolecular repulsion between molecules
At certain conditions, attractive forces among gas molecules exceed repulsive forces. Which of the following statements is NOT true?
The fugacity coefficient is less than 1
The compressibility factor is less than 1.
The fugacity is greater than the pressure.
The ideal volume is greater than the actual volume.
A mole of which gas has the smallest volume at 0°C and 1 atm?
He
CO2
SO2
Xe
ΔE_univ = ΔE_sys + ΔE_surr = 0 can also be stated as
H = E + PV
ΔS_total < 0
ΔG = ΔH - TΔS
ΔE = Q + W
Which is TRUE about a gas that is compressed isothermally?
W > 0; Q > 0
W < 0; Q < 0
W < 0; Q > 0
W > 0; Q < 0
In Figure 3.2, reversible isothermal work of expansion done is represented by which areas?
1 only
1+2
1-2
2 only
The value of the internal pressure of an ideal gas is always
<1
zero
>1
positive
In the equation of the difference between heat capacities at constant pressure and volume, alpha and beta were incorporated constants. The constant beta is called
coefficient of thermal expansion
Van der Waals expansion factor
virial coefficient
isothermal compressibility factor
The equation ΔH = ΔU + PΔV is applicable for which process?
isobaric
isothermal
isochoric
isentropic
Which of the following is TRUE?
Ionization energy is exothermic while electron affinity is endothermic.
Ionization energy is endothermic while electron affinity is exothermic.
Both ionization energy and electron affinity are exothermic.
Both ionization energy and electron affinity are endothermic.
Which of the following statements about phase transitions is true?
Melting is endothermic and freezing is exothermic.
Vaporization is exothermic and condensation is endothermic.
The enthalpy change for a spontaneous phase transition is always positive.
The enthalpy change for a spontaneous phase transition is always positive.
The enthalpy of formation of NOCI from gaseous nitrogen, oxygen, and chlorine is 12.57 kcal/mol at 25°C. What is the value of ΔE?
53.8 kJ
55.1 kJ
13.8 kJ
15.1 KJ
Which of the following equations is(are) TRUE for a reaction inside a bomb calorimeter?
I. ΔE = q
II. ΔE = ΔH - VΔP
Both I and II
I only
II only
Neither I nor II
Kirchhoff's Law is applicable to a system when _______
the temperature is constant
all the heat capacities are known in the range being examined
the heat capacity is measured at constant pressure
one assumes that all the heat capacity values are independent of temperature
A 2-g sample of solid RbCIO4 is added to 100-g water initially at 23.00°C in an insulated container. The final temperature is 21.56°C. What is the enthalpy of dissolution (kJ/mol) of the perchlorate solid?
56.8 kJ/mol
-0.615 kJ/mol
0.615 KJ/mol
13.6 KJ/mol
For which of the following reactions is the change in the enthalpy of the system equal to the change in the internal energy?
H2 reacting with O2 to form H2O in a bomb calorimeter
an aqueous solution of HCl reacting with an aqueous solution of NaH to form an aqueous solution of NaCl and H2 gas.
CO2 gas reacting with solid NaOH to form solid NaHCO3.
solid Pb(NO3)2 reacting with solid KI to form solid PbI2 and solid KNO3.
Ail of the following statements about ΔS are true EXCEPT
It is a measure of energy dispersal.
The natural tendency is for it to increase.
It is not a state function.
it can be defined both thermodynamically and statistically.
Amphiphilic species can aggregate into micelles in water. Which of the following best explains why the overall ΔS of micelle formation is positive?
Amphiphilic compounds are solvated by an ordered layer of water molecules.
Micelle formation involves converting many independent amphiphilic compounds into single large micelle.
Water molecules are trapped in the hydrophobic interior of molecules.
Water molecules form ordered structures around the exterior of micelles.
If a process is not isochoric. not isobaric, nor isothermal, which of the following equations for the change in entropy can be used?
ΔS = Cv In(T2/T1)
ΔS = Cp In(T2/T1)
ΔS = nR In(V2/V1)
ΔS = Cv In(T2/T1) + nR In(V2/V1)
What is the ΔS (J/1-K) of the process when 12 kg of water at 7°C is mixed with 4 kg of water at 80°C. Assuming the container is isolated to the surroundings.
60
140
280
350
When filled balloon is immersed in liquid nitrogen, which best describe the changes as the balloon deflates?
I. The nitrogen does work on the balloon.
II. The entropy of the nitrogen increases.
Both I and II
Neither I nor II
I only
II only
Which is NOT a step in the Carnot cycle?
Isothermal expansion with addition of heat
Adiabatic decrease in temperature
Isothermal compression with release of heat
Isentropic compression with release of heat
Which isomer of C4H8 has the lowest absolute entropy at 25°C?
cyclobutane
cis-2-butene
1-butene
trans-2-butene
Which represent(s) a measure of energy distribution?
I. Temperature
II. Internal Energy
III. Entropy
IV. Partition Function
I Only
I, II, and III
II, III and IV
III and IV
What is the absolute entropy (x10^23 J/K) of a system that has 45 microstates?
5.26
29.5
48.3
62.1
Based on the Third Law of Thermodynamics, all perfect crystals at absolute zero have
the same enthalpy
the same entropy
different ΔA values
both A and C
Given that dU = TdS PdV and that H = U + PV, which of the following is TRUE?
dH = TdS + VdP
dH = dU + PdV
dH = SdT - VdP
dH = dU - TdS
At constant T and P, a system will be in equilibrium when which of the following quantities is at miniature?
W
H
A
G
The Helmholtz free energy is positive when changes in internal energy and entropy are both positive at
high temperatures
all temperatures
low temperatures
only at absolute zero temperature
Which is equivalent to dG/dP at constant temperature?
Volume
Enthalpy
Entropy
Work
Liquid water is injected into an oven at 400 K. What are the signs of ΔG, ΔK and ΔS of the process?
+ , + , +
- , - , -
- , + , +
+ , - , +
The given reaction is performed at 298 K.
2N0(g) + O2(g) = 2NO2(g) Kp = 1.6 x 10^12
The standard free energy of formation of NO(g) is 86.6 KJ/mol at 298 K. What is the free energy of formation of NO2(g) at the same temperature?
R (298) In 1.6x10^12- 86.6x10^3
86.6x10^3 + R (298)
In 1.6x10^2
86.6x10^3 - R(298)
In 1.6x10^2
0.5[2(86x10^3) - R (298) In 1.6x1012]
A reaction has Keq = 0.020 at 300 K, and its Keq value increases with increasing temperature. What can be inferred about the values of ΔH*rxn and ΔS*rxn, assuming that they are independent of temperature?
I. ΔH°rxn <0
II. ΔS°rxn <0
II only
Neither I nor II
I only
Both I and II
How can a gas be made to conduct electricity?
by increasing temperature
by using low pressure and high voltage
by increasing volume
by increasing pressure and voltage
What is the slope of the linear equation used for the molar conductivity determination of strong electrolytes?
Kohlrausch coefficient
Ionization constant
Limiting molar conductivity
Reciprocal of limiting molar conductivity
In an isolated system...this reaction: Zn + 2H = H2 + Zn2+ is much more likely to take place than this: Zn + Cu2+ = Cu + Zn2+. Which explains this?
Nernst Law
First Law of Thermodynamics
Coloumb's Law
Second Law of Thermodynamics
What is the voltage of a circuit with 10 mA if series resistors A (2 kΩ) and B (1 kΩ) are in parallel with resistor C (0.5 kΩ)?
4.3V
9.3V
14.3V
20.3 V
How much silver will be deposited if 80 mA current was passed through for one hour?
0.15g
0.30g
0.45g
0.60g
Which of the following devices measure electrode potential?
electrometer
pyrometer
galvanometer
voltmeter
Which is an expression for the limiting molar conductivity of BaCl2?
Λm BaCl2 = (λBa2+) + λCl-
Λm BaCl2 = (λBa2+) + λCl2-
Λm BaCl2 = ΛmBa(NO3)2 + ΛmNaCl - ΛmNaNO3
Λm BaCl2 = ΛmBa(NO3)2 - 2ΛmNaCl - 2ΛmNaNO3
A Hithorf Cell initially contains 0.1 HCl. What will be the concentration of HCl in the middle of compartment after electrolysis
0M
0.1M
>0.1M
<0.1M
The cgs unit for surface tension is erg/cm^2. How many times is the value larger than SI
100
200
1000
2000
The energy between molecule between two phases is intermediate between that of the free molecule and that of the molecule in the bulk. Its potential energy would be reduced if it is moved into the bulk, thus molecules are under the influence of a force which tends to draw them into the bulk. This force is called __________.
Flux
Adhesive Force
Viscosity
Surface Tension
One millilliter of water is broken into droplets with radius of 10^-5cm The surface tension of water is 72.75 x 10^-3 N/m, what is the Gibbs free energy of the fine droplets relative to water
0.52 Cal
0.78 cal
1.12 cal
1.45 cal
Which of the following liquids will be the most viscous?
1-butanol
n-pentane
dimethyl ether
1-methylbutane
The velocity of the suspended particles in Brownian motion depends on
mass of the particle and density of the liquid
density and viscosity of the liquid
mass of the particle and viscosity of the liquid
mass of the particle and temperature of the liquid
Which of the following describes how purity affects the chemical properties of a substance?
Well-defined boiling point
Well-defined melting point
high conductivity
predictable products from reactions
Which of the following is TRUE at extremely high temperatures?
The chemical potential of solid, liquid and gas are all equal.
The chemical potential of gas is the lowest
Solid is the most stable phase
None of the above.
Which of the following is TRUE about the triple point of water
Us ≠ UL ≠ Uv
Us = UL ≠ Uv
Us = UL = Uv
Us ≠ UL = Uv
The system CaCO3: CaO: CO2 has [component(s), phase(s), variance(s)] values.
3,1,2
2,2,1
2,3,1
3,2,3
The melting point of water decreases with increasing pressure. Which is the best explanation for this observation?
Liquid water is denser than solid water at 0°C
Melting of ice is endothermic at 0°C
The vapor pressure of liquid water is lower than the vapor pressure of solid water at 0°C.
Solid and Liquid water cannot coexist at equilibrium at 0°C at pressures not equal to 1 atm
What is the boiling point of water in a pressure cooker at 2.0atm?
101°C
121°C
141°C
191°C
What will happen if liquid water is immediately transferred in a vacuum container?
It will freeze.
Noting, will happen
It will decompose
It will vaporize
Which of the following is TRUE for ideal solutions?
I. Δmix H = 0
II. Δmix S = 0
III. P solution = ∑Pi
IV. Δmix G = -R∑nilnxi
I only
I and III
II and III
I, III and IV
Which of the following does NOT indicate a negatively-deviating system after mixing?
Warming Effect
Expansion
Lower vapor pressure than ideal
Similar polarity of solute and solvent
At 10°C, the vapor pressure of a liquid is 3.21kPa while at 20°C it is 5.86 kPa, what is the heat of vaporization of the liquid?
10.1 KJ/mol
31.8 KJ/mol
41.5 KJ/mol
63.4 KJ/mol
The Henry's Law constant for carbon dioxide in water at 25°C is 30 atm/M. The concentration of dissolved gas in a vessel pressurized with 2 atm is ______.
1.5 M
0.067 M
0.15 M
0.0067 M
it means "easily melted".
azeotrope
eutectic
peritectic
plait
Refer to Figure 3.3, which of the following is TRUE?
The eutectic point is at approximately 1580°C
At 1600°C and XMg2SiO4 = 0.10, there is no solid Qz
At peritectic point, there is no liquid MgSiO3
At 500°C and XSiO2 = 0.1, fo-rich phase dominates
Which of the following statements is FALSE for very dilute aqueous solution
Activity coefficient approaches one
Activity approaches the concentration
Molarity approaches molality.
Van't hoff factor approaches 1.
Which solution will have the lowest freezing point each having equal concentration?
Ca(NO3)2
KCl
HF
All equal
Acetic acid that is 7.7% dissociated in 100mL of water has a boiling point of 100.23°C. How much acid is present?
2.50g
2.90g
2.70g
3.10g
Which statement best describes the variation of the reaction rate constant with temperature?
The rate constant does not change with temperature because it is an unvarying characteristic of the specific ration
The rate constant typically decreases with increasing temperature because fewer molecules are able to adopt the required orientation at higher temperature.
The rate constant typically increases with increasing temperature because increasing the temperature increases the fraction of collisions that result in reaction.
The rate constant typically increases with increasing temperature because most reactions become more favorable as the temperature increases.
The activated-complex theory (or transition state theory) assumes that an equilibrium exists between the ____________.
Activated complex and reactants only
Activated complex and products only
reactants and products only
reactants, products, and activated
The forward rate constant of a reversible reactions is 4x10^-7 Ms^-1 and equilibrium constant is 1x10 ^-2. What is the backward rate constant (Ms)^-1
4x10 ^-7 Ms ^-1
4x10 ^-11 Ms ^-1
4x10 ^-9 Ms ^-1
4x10 ^-5 Ms ^-1
If the elementary step A --> B has a reaction enthalpy of -50kJ and activation energy of 10 kJ. The activation energy for the reverse step B --> A is
10 kJ
40 kJ
50 kJ
60 kJ
For the reaction shown below, the rate of consumption of NOBr was -1.6x10 ^ -4 mol L^-1 s^-1. What would be the rate of the reaction in mol L^-1 s-1 ?
2NOBr --> 2NO + Br
-1.6 x 10^-4
8.0x10^-5
1.6 x 10^-4
3.2x10^-4
For a certain reaction A + B --> C, it was noted that when the initial concentration of A is doubled while B is held constant, the initial reaction rate doubles, and when the initial concentration of B is doubled while A is held constant, the initial reaction rate increases fourfold. What is the rate expression for this reaction?
rate = k[A][B]
rate = k[A][B]^2
rate = k[A]^2[B]
rate = k[A]^2[B]^3
What is the reaction order of the reaction given the following data
0
1
2
3
The gas phase decomposition of NOBr in the following reaction is second order with respect to NOBr with a half-life of 96 seconds. What is the percentage of NOBr reacted after 66 seconds? 2NOBr --> 2NO + Br2
40.74%
74.42%
59.26%
25.58%
Consider the proposed mechanism for the destruction of ozone in the stratosphere
03 + Cl --> ClO + O2
ClO + O3 --> Cl + 2O2
Cl- is a catalyst
O2 is an intermediate
Equal amount of Cl-1 and ClO- are present
The number of moles of O2 produced equals the number of moles of O3 consumed
Even though graphite is thermodynamically more stable than diamond at standard conditions, a diamond will not be converted into graphite over a span of thousands of years. Which explains this?
The ΔG for the change from diamond to graphite is greater than zero.
The ΔS for the change from diamond to graphite is less than zero
The change from graphite to diamond proceeds relatively faster
The change from diamond to graphite has very large activation energy.
What are the signs of ΔG, ΔH and ΔS of a spontaneous adsorption?
+, +, -
-,-,+
+, -, -
-, -, -
Which of the following is TRUE?
Freundlich isotherm is not applicable for multi-layer adsorption
The exponent of the Freundlich isotherm can be any positive vale
The fraction of the surface covered in the Langmuir isotherm is the q/qmax
None of the above.
What is the length (angstrom) of a molecule that has a molar mass of 285g/mol and a density of 0.85g/mL? it occupies an area of 0.205nm^2 in a close-packed surface film.
27Å
38Å
49Å
62Å
The volume ratio of a colloidal to a solute particle is closest to
0.001
1000
10
10^22
Which of the following is TRUE about gold number?
Its value decreases as the protective increases
Its value decreases as the protective decreases
It is the milligrams of gold sol needed to prevent coagulation of 10mL of the substance
It is the gramas of substance needed to prevent coagulation of 10mL standard gold sol.
Which of the following is TRUE
Heavier, more stable nuclei somewhat larger number of protons than neutrons.
Unstable nuclei do not spontaneously change to nuclei with stable configurations
Usually, lighter stable nuclei have equal numbers of neutrons and protons
Nuclei can never have an equal number of protons and neutrons
Control rods in nuclear reactors are commonly made of Boron and Cadmium because these two can _______.
absorb neutrons
emit neutrons
decrease the speed of the neutrons
increase the speed of the neutrons
N-13 will most likely undergo which decay
aplha decay
beta decay
positron emission
electron capture
For the radioactive decay of radium, 226, 88Ra --> 222 86Rn + 4,2He what is the Δ when 10.2g of radium decays? mass (amu) 4 2 He = 4.0015g, 222 86Rn = 221.9703g; 226, 88 Ra = 225.9771g
-2.2 x 10^7 KJ
-2.4x10^-4 KJ
2.2x10^7 KJ
5.3x10^-3 KJ
Br-82 has a half-life of 36 hours. A sample containing Br-82 was found to have an activity of 1.2x10^5 disintegrations in 5 minutes. How many grams of Br-82 were present in the sample, assuming no other radionuclide is present?
5.1x10^-14 g
18.4x10^-11 g
5.8x10^-9 g
1.1x10 -14 g
Uranium-235 is one of the most common fuels used in nuclear power plants. On the other hand, Uranium-238 cannot be used as a fuel in a nuclear power plant. which of the following best explains why Uranium-238 cannot be used as a fuel
Uranium-238 does not undergo radioactive decay.
Uranium-238 does not undergo fission easily enough to be used as a fuel.
There is not enough Uranium-238 in naturally occurring uranium to use it as a fuel.
Uranium-238 is not a naturally occuring isotope of uranium
Ca-41 undergoes radioactive decay by electron capture. Which statement(s) about its decay product is (are) correct?
I. The decay product is an isotope of Sc
II. The decay product has a slightly larger mass than Ca-41
Neither 1 nor II
I only
Both I and II
II only
A banana contains 600mg potassium, 0.0117% of which is radioactive K-40 if 1g of K-40 has an activity of 2.6262x10^5 Bq, what is the activity of the banana?
10.1
15.3
18.4
27.0
It is highly dependent on the moment of inertia and the angular velocity of the molecule
electronic energy
rotational energy
vibrational energy
nuclear energy
The harmonic oscillator is a good model for ________.
Molecular vibration
Molecular translation
Molecular rotation
Molecular diffusion
Which of these expressions describes the radius of a hydrogen electron in the Bohr model
(ε₀h2n2)/(4πme^2)
(4πε₀h^2n^2)/(me^2)
(4πme^2)/(ε₀h2n2)
ao
What is the eigenvalue of (f) = A sin(kx) if it is operated using Hamiltonian operator for a particle in a one-dimensional box?
A
K
-Ak
-k^2
For which one of the following species is it possible to solve the Schrodinger equation analytically and obtain an equation for its electronic energy levels?
He
H
H2
Li
Guys an halaba nga schrodinger equation ha back page
H anion
H2 molecule
He atom
He cation
Which helium wave function for excited states obeys the Pauli's exclusion principle?
[1s(1) 2s(2) + 2s(1) 1s(2)] [α(1) α(2)]
[1s(1) 2s(2) + 2s(1) 1s(2)] [β(1) β(2)]
[1s(1) 2s(2) + 2s(1) 1s(2)] [α(1) β(2) + β(1) α(2) ]
[1s(1) 2s(2) + 2s(1) 1s(2)] [α(1) β(2) - β(1) α(2) ]
How many angular nodes are there in a 4p orbital?
0
1
2
3
