PHYSICAL CHEMISTRY Flashcards by John Clavines Edradan

An ideal gas will only be considered in the
following operating parameters:

a. High Temperature, High Pressure
b. High Temperature, Low Pressure
c. Low Temperature, High Pressure
d. Low Temperature, Low Pressure

b. High Temperature, Low Pressure

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Which of the following is false regarding absolute
zero?

a. All molecules will stop moving
b. Absolute zero can be achieved
c. Temperature is 0K
d. Temperature is 0R

b. Absolute zero can be achieved

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For a real gas, what causes the deviation from the
ideal pressure at a molecular level?

a. Energy is lost for each collision against
the sides of the container
b. Energy is lost due to the collision of
molecules with one another
c. Intermolecular forces of attraction of the
molecules with one another
d. Molecules randomly hit the sides of the
wall with less force than usual

c. Intermolecular forces of attraction of the
molecules with one another

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When gas molecules collide, they experience
_____ collision.

a. Perfectly elastic
b. Imperfect elastic
c. Perfectly inelastic
d. Imperfect inelastic

a. Perfectly elastic

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Which of the following is false with KMT?

a. Gas molecules move in random motion
b. Due to collision of gas molecules with
each other, some kinetic energy is lost
c. The temperature of the whole system
does not change with time
d. The size of the molecules are negligible

b. Due to collision of gas molecules with
each other, some kinetic energy is lost

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The internal energy of an ideal gas depends on:

a. Volume
b. Absolute temperature
c. Pressure
d. Number of moles

b. Absolute temperature

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The state of an ideal gas is changed in a closed
path 1→2→3→4→1. Which of the following is
true about the work done on the gas?

| P  |    2  \_\_\_\_\_\_\_\_\_\_\_\_\_ 3
|       |                    |
|    1 |\_\_\_\_\_\_\_\_\_\_\_\_|4
|
|\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
                  V

a. W12>0, W23=0, W34<0, W41=0
b. W12<0, W23=0, W34=0, W41>0
c. W12=0, W23>0, W34=0, W41<0
d. W12=0, W23<0, W34=0, W41>0

d. W12=0, W23<0, W34=0, W41>0

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Which of the following is a characteristic of an
adiabatic process?

a. ΔU=0
b. W=0
c. Q=0
d. ΔV=0

c. Q=0

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A sample of an ideal gas has an internal energy of
U and is then compressed to ½ of its original
volume while the temperature stays the same.
What is the new internal energy of the ideal gas
in terms of U?

a. U
b. U/2
c. U/4
d. 2U

a. U

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Which of the following is not conserved in any
process?

a. Mass
b. Energy
c. Momentum
d. Entropy

d. Entropy

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An isentropic process is:

a. Isothermal and adiabatic
b. Reversible and isothermal
c. Reversible and adiabatic
d. Reversible and isochoric

c. Reversible and adiabatic

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Increasing the temperature of the cold reservoir
_____ the Carnot efficiency.

a. Increases
b. Decreases
c. Does not change
d. NOTA

b. Decreases

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If the entropy of a system decreases, the entropy
of its surroundings

a. Must always increase
b. Must always decrease
c. May increase or decrease
d. Not enough information to answer the
question

a. Must always increase

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Which of the following is not true?

a. (
𝜕𝐺
/𝜕𝑃)
𝑇
= 𝑉
b. (
𝜕𝐻
/𝜕𝑃)
𝑇
= 𝑉
c. (
𝜕𝐺
/𝜕𝑇)
𝑃
= −𝑆
d. (
𝜕𝐻
/𝜕𝑉)
𝑇
= −𝑆

d. (
𝜕𝐻
/𝜕𝑉)
𝑇
= −𝑆

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The amount of heat absorbed when CO2 gas
reacts with a solid CaO to form solid CaCO3 is
measured in a bomb calorimeter. The data
obtained give a direct measure of:

a. ΔU
b. VΔP
c. ΔH
d. Cp

a. ΔU

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Heat required to raise the temperature of 1lbm of
water by 1˚F.

a. Calorie
b. BTU
c. Specific heat
d. Heat capacity

b. BTU

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Which of the following statements is/are true?
1. The criterion of equilibrium at constant
temperature and pressure is dG=0.
2. For a reversible process, dS=dQ/T.

a. 1 only
b. Both 1 and 2
c. 2 only
d. None of the above

b. Both 1 and 2

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The general statement of the Third Law of
Thermodynamics is attributed to:

a. Nikolaus Otto
b. Jacobus Clapeyron
c. William Clausius
d. Walther Nernst

d. Walther Nernst

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The equilibrium intensive state of a system is
described by specifying the temperature,
pressure, and:

a. Mole fractions
b. Number of moles
c. Volume
d. Chemical potential

a. Mole fractions

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The fugacity of a real gas is equal to:

a. The pressure of an ideal gas which has
the same chemical potential as the real
gas
b. The pressure of a real gas which has the
same chemical potential as the ideal gas
c. The chemical potential of an ideal gas
which has the same pressure as the real
gas
d. The chemical potential of a real gas
which has the same pressure as the ideal
gas

a. The pressure of an ideal gas which has
the same chemical potential as the real
gas

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An adiabatic process is one in which the system
under investigation is thermally isolated so that
there is no exchange of heat with the surroundings. Thus, the work done on a closed
system in an adiabatic process is _____.

a. Equal to zero
b. Not equal to the exchange of heat with
surroundings
c. Equal to the increase in internal energy of
the system
d. Not equal to the increase in internal
energy of the system

c. Equal to the increase in internal energy of
the system

If enthalpy is defined as present in a constant
pressure process change of state, using the
relationship of ΔH=ΔU+ΔPV, where H is
enthalpy, U is the energy change in the system
and PV represents pressure and volume states,
determine the ΔU and ΔH of 1kg of water when
vaporized at constant temperature of 100˚C and
constant pressure of 101.35kPa. The specific
volumes of liquid and vapor water are 0.001041
and 1.67m3
/kg. An amount of 2257kJ of heat is
added to the water.

a. ΔU=2087kJ; ΔH=2257kJ
b. ΔU=2378kJ; ΔH=2221kJ
c. ΔU=2226kJ, ΔH=2378kJ
d. None of these

a. ΔU=2087kJ; ΔH=2257kJ

A certain gas confined in a cylinder by a piston,
where the initial pressure in the system is 7 bar
and the volume is 0.11 cubic meter. The piston is
held in place by latches and the apparatus is in
vacuum. Determine the change in energy when
the latches are removed suddenly and the gas
expands to double its initial volume and the piston
strikes the latches at the end of the process.

a. 11.54kJ
b. 0.77kJ
c. 0.59kJ
d. No change

d. No change

Define entropy.

a. Entropy is a function of the state of the
system and determines whether a
physical change or chemical reaction can
occur simultaneously in a closed system
b. Entropy is the opposite of enthalpy
c. Entropy determines the time required for
a reaction to proceed and complete
d. All of these

d. All of these

Determine whether the changes in entropy (ΔS) and enthalpy (ΔH) are positive, negative, or near zero. 1. Ethyl alcohol evaporating from glass container 2. A diatomic molecule dissociates into atoms 3. Charcoal is burned to form CO2 and water a. 1. ΔH>0, ΔS>0; 2. ΔH>0, ΔS>0; 3. ΔH>0, ΔS>0 b. 1. ΔH<0, ΔS<0; 2. ΔH>0, ΔS<0; 3. ΔH>0, ΔS<0 c. 1. ΔH>0, ΔS<0; 2. ΔH<0, ΔS>0; 3. ΔH>0, ΔS>0 d. 1. ΔH<0, ΔS>0; 2. ΔH<0, ΔS<0; 3. ΔH<0, ΔS<0

a. 1. ΔH>0, ΔS>0; 2. ΔH>0, ΔS>0; 3. ΔH>0, ΔS>0

Choose the process that occurs with a decrease in entropy. a. Freezing of water b. Boiling of water c. Dissolving salt in water d. Sublimation of dry ice

a. Freezing of water

A vessel of volume 22.4 dm3 contains 2 mol H2 and 1 mol N2 at 273.15 K. What is the total pressure inside the vessel? Assume ideal gas. a. 1 atm b. 2 atm c. 3 atm d. 4 atm

c. 3 atm

In an industrial process, nitrogen is heated to 500 K at a constant volume of 1 m3 . The gas enters the container at 300 K and 100 atm. Use the Van der Waal’s equation to determine the approximate pressure of the gas at its working temperature of 500 K. For nitrogen, a = 1.352 dm6 -atm / mol2 , b = 0.0387 dm3 /mol. a. 120 atm b. 140 atm c. 160 atm d. 180 atm

d. 180 atm

A perfect gas undergoes isothermal compression, which reduces its volume by 1.8 dm3 . The final pressure and volume of the gas are 1.97 bar and 2.14 dm3 , respectively. Calculate the original pressure of the gas. a. 10.5 bar b. 1.07 bar c. 750 torr d. 850 torr

b. 1.07 bar

At 100 ˚C and 1.6 kPa, the mass density of phosphorus vapor is 0.06388 kg/m3 . What is the molecular formula of phosphorus under these conditions? a. P b. P2 c. P3 d. P4

d. P4

A 1 dm3 glass bulb contains 1x1023 H2 molecules. If the pressure exerted by the gas is 100 kPa, assuming ideal gas, determine the temperature of the gas. a. 56.54 K b. 72.43 K c. 103.64 K d. 159.64 K

b. 72.43 K

5000 J of heat are added to 2 mol of an ideal monoatomic gas, initially at a temperature of 500 K, while the gas performs 7500 J of work. What is the final temperature of the gas? a. 200 K b. 300 K c. 400 K d. 500 K

c. 400 K

What is the final temperature of a sample of argon of mass 12 g that is expanded reversibly and adiabatically from 1 dm3 and 273.15 K to 3 dm3 ? a. 122 K b. 131 K c. 145 K d. 159 K

b. 131 K

A sample of 4.5 g of methane occupies 12.7 dm3 at 310 K. Calculate the work done when a gas expands isothermally against a constant external pressure of 200 torr until its volume has increased by 3.3 dm3 a. -79 J b. -150 J c. -126 J d. -88 J Calculate the work that would be done if the same expansion occurred reversibly and isothermally. a. -150 J b. -167 J c. -103 J d. -120 J

d. -88 J b. -167 J

(Nov. 2019 PBE) Applying the combined gas laws, determine the volume of 1 mol of Ne(g) in a flask at the temperature of 25 ˚C and a pressure of 1 atm. a. 12.2 L b. 18.6 L c. 32.21 L d. 24.51 L

d. 24.51 L

(Nov. 2019 PBE) In the combustion of 25 g of methane gas, what is the volume of oxygen required at 25 ˚C and 0.21 atm? a. 411 b. 298 c. 363 d. 521

c. 363

(Nov. 2019 PBE) Determine the volume of carbon dioxide in cubic feet occupied by 120 lb at a pressure of 1.5 atm. a. 750 b. 490 c. 560 d. 680

a. 750

(Nov. 2019 PBE) If 1 mol of an ideal gas is kept at 0 ˚C, during an expansion from 3.0 to 10.0 L, examine and calculate how much work is done as the gas during expansion. a. -2.2x10^4 J b. -5.4x10^3 J c. -7.8x10^4 J d. -2.7x10^3 J

d. -2.7x10^3 J

(Oct. 2021 PBE) In a gas mixture containing 100 mg/L of H2S gas at 25 ˚C and 1 atm, determine the partial pressure exerted by the gas. a. 0.071 b. 0.003 c. 0.101 d. 0.006

a. 0.071

Which of the following does not have a zero enthalpy of formation at 298.15K? a. Li(g) b. He(g) c. Hg(l) d. Br2(l)

a. Li(g)

Calculate the enthalpy change of the reaction (in kJ/mol). CS2(l) + 3O2(g) → CO2(g) + 2SO2(g) C(s) + O2(g) → CO2(g); ΔHF = -393.5 kJ/mol S(s) + O2(g) → SO2(g); ΔHF = -296.8 kJ/mol C(s) + 2S(s) → CS2(l); ΔHF = 87.9 kJ/mol a. -900 b. -1100 c. -1300 d. -1500

b. -1100

(Nov. 2019 PBE) Calculate the net and the gross heats of combustion for methane gas. a. -491 kJ; -998 kJ/mol b. -362 kJ; -731 kJ/mol c. -891 kJ/mol; -802 kJ/mol d. -598 kJ; -1120 kJ/mol

c. -891 kJ/mol; -802 kJ/mol

(Nov. 2019 PBE) If 5 g of methane gas is burned at constant pressure, determine the heat released in kJ if the change in entropy that accompanied the reaction is -890 kJ. a. -360.00 K b. -250.01 K c. -278.12 K d. -192.00 K

c. -278.12 K

(Oct. 2021) The standard molar enthalpy change is -905 kJ for the oxidation of ammonia, 4NH3(g) + 5O2 → 4NO(g) + 6H2O(g). Analyze and calculate the standard molar enthalpy of formation for ammonia based on the following standard enthalpies of formation: HF[NO(g)] = +90 kJ/mol; and HF[H2O(g)] = - 240kJ/mol a. -227 kJ/mol b. -500 kJ/mol c. -406 kJ/mol d. -692 kJ/mol

a. -227 kJ/mol

A block of iron weighing 3.6 kg at a temperature of 807 ˚C was inserted into a container containing 1 L of water at a temperature of 30 ˚C isolated from the environment. The cooling process of iron happens in two steps, the first phase the water is heated the boiling point and in the second stage the water evaporates. The phase continues until the temperature of the iron is equal to the temperature of the water. The final temperature of the water and the iron is 100 ˚C. The specific heat of solid iron is 0.45 J/g-K and the heat of vaporization for water is 2259.23 J/g. The energy given off by the iron block in MJ is nearest to: a. 1.1 b. 1.3 c. 0.7 d. 0.9 How much sensible heat was used by the water to get to its boiling point in J? a. 200,000 b. 300,000 c. 400,000 d. 500,000 The amount of water vaporized in grams in this process is nearest to: a. 200 b. 300 c. 400 d. 500 If the density of water at all temperatures is 1 g/mL, The amount of water left in the container in L is: a. 0.5 b. 0.6 c. 0.7 d. 0.8

a. 1.1 b. 300,000 c. 400 b. 0.6

A 2 kg open calorimeter at 100 ˚C has a heat capacity of 4 kJ/K. 100 g of ice at -10˚ C was placed inside the calorimeter. If CP of ice = 0.5 cal/g-K and latent heat of fusion is 80 cal/g, Calculate the final temperature in ˚C. a. 78 b. 82 c. 86 d. 90 Calculate the entropy change of the calorimeter in cal/K. a. -184 b. -92 c. -46 d. -24 Calculate the entropy change of the ice in cal/K. a. 200 b. 100 c. 60 d. 40 Calculate the entropy change of the universe in cal/K. a. 12 b. 14 c. 16 d. 18

b. 82 c. -46 c. 60 a. 12

Ethanol may be treated as an incompressible fluid at an appreciable pressure range. If the pressure is changed from 1 bar to 3 bar at 350 K, what is the change in the Gibbs free energy in J/g? The density of ethanol at this temperature is 800 kg/m3 . a. 0.25 b. 2.5 c. 25 d. 250

a. 0.25

What is the minimum work in BTU required to produce 20 lb of ice from water at 32 ˚F if the surrounding air is 85 ˚F and the latent heat of fusion of ice is 143.4 BTU/lb? a. 300 b. 310 c. 320 d. 330

b. 310

It is the property of a fluid that is caused by shearing effect of a fluid layer moving past another layer. a. Density b. Viscosity c. Flow d. Compressibility

b. Viscosity

A sphere of radius 5 mm and density of 1.1 g/cm3 falls at a constant velocity through a liquid of density 1 g/cm3 and viscosity of 1 cP. What is the velocity of the falling sphere in m/s? a. 1.36 m/s b. 2.72 m/s c. 5.45 m/s d. 10.88 m/s

c. 5.45 m/s

An Ostwald Viscometer is used to measure the viscosity of a monoatomic gas. The inlet and outlet pressures of the gas are 1.1 atm and 1.08 atm. What is the viscosity in μP of 100 mL of this gas measured at 300 K if it took 5 s for the gas to flow through a 0.5 m tube of 1 mm diameter? a. 0.5 b. 5 c. 50 d. 500

c. 50