WorksheetsORC - Unit 4 Part 2 Practice Exam 22/23
Total questions: 20
Worksheet time: 39mins
QT 4.1
An isolated system allows for the flow of …?
heat
kinetic energy
none of these
matter
QT 4.5
The volume of a piston in an internal combustion engine increases in volume by 100 ml
against a pressure of 20 atm. What is the work done?
(Conversion factor: 1 liter-atm = 100J)
200 J of work done on the system
200 J of work done by the system
2 J of work done on the system
2 J of work done by the system
QT 4.4
Which of the following statements is/are true concerning the first law of thermodynamics?
I) The internal energy (E) of the universe is conserved.
II) The internal energy of a system plus that of its surroundings is conserved.
III) The change in internal energy ( E) of a system and its surroundings can have the same sign.
I, III
I only
I, II, III
I, II
QT 4.6
A cell phone battery has a change in internal energy, ΔE, of 500 kJ as it powers a cell phone. If 50 kJ of that energy warms the hand holding the cell phone, how much work was done to watch a YouTube video?
+450 kJ
-450 kJ
-550 kJ
+550 kJ
QT 4.7
Dr. Laude explodes a gummy bear in a bomb calorimeter. The temperature increase for the 250 grams of water surrounding the calorimeter is 20 degrees. The bomb housing has a heat capacity of 250 J/℃. How much energy is in a gummy bear? (The heat capacity of water is 4 J/g℃)
250 kJ
25 kJ
20 kJ
200 kJ
QT 4.11
Which of the following is NOT TRUE about heats of formation for a compound?
All reactants and products must be one mole quantities.
The reactants in a formation reaction are elements in their standard states.
Standard conditions in a formation reaction are 1 atmosphere and 298K
Formation reactions produce a mole of product that can be in any state
QT 4.10
Calculate the ΔHrxn for the theoretical reaction of
C ===> 2A + B
Given
C ===> B + D ΔHrxn = 200 kJ
2A ===> D ΔHrxn = -200 kJ
0 kJ
400 kJ
-400 kJ
200 kJ
QT 4.11
What is the heat of reaction for the formation of hydrogen peroxide below given:
H2O(l) + ½O2(g) ===> H2O2(l)
the heat of formation of hydrogen peroxide, H2O2(l) , is -185 kJ/mole
the heat of formation of water, H2O(l) , is -285 kJ/mole?
-100 kJ/mole
Not enough information is given to solve the problem.
-185 kJ/mole
+100 kJ/mole
QT 4.13
Which of the following compounds has the greatest absolute molar entropy?
A mole of hexane (C6H14) in the gas phase
A mole of hexane (C6H14) in the liquid phase
A mole of cyclohexane (C6H12) in the gas phase
A mole of cyclohexane (C6H12) in the liquid phase
QT 4.13
Which one shows the substances in the decreasing order of their molar entropy?
H2O(l) >CO2(g) > Ne(g) > Ar(g)
CO2(g) > Ar(g) > Ne(g) > H2O(l)
CO2(g) > H2O(l) > Ne(g) > Ar(g)
H2O(l) > Ne(g) > Ar(g) > CO2(g)
QT 4.14
Consider the processes
I) NaCl(s) → Na+(aq) + Cl─(aq)
II) CaCO3(s) → CaO(s) + CO2(g)
III) H2O(l) → H2O(s)
Which entropy will increase as the process proceeds from left to right?
I only
I, II
III only
I, II, III
QT 4.14
Without performing any calculations, determine whether the entropy of the system increases or decreases in:
Cl2(g) + H2O(l) → HCl(aq) + HOCl(aq)
Decreases
Increases
Unable to determine
The entropy does not change
QT 4.15
Which of the following statements is not true concerning the second law of thermodynamics?
The entropy of the surroundings is determined by the entropy of the system
A perfect crystal at 0 K has an absolute entropy of 0
The number of microstates in the universe is always increasing
The entropy of the universe is always increasing
QT 4.16
What are the ΔSuniv, ΔSsys, ΔSsurr for H2O(s) → H2O(l) at -10℃? Hint: the first step is to ask whether the reaction is spontaneous.
+, ─, ─
─, ─, ─
─, +, ─
The universe is too large to make this determination
QT 4.15
A hydrogen balloon explodes at room temperature releasing 600 kJ of energy to the surroundings. What is the ΔSsurr?
-2 kJ/K
2 kJ/K
2 J/K
-2 J/K
QT 4.17
Why is there a temperature at which hydrogen balloons stop exploding spontaneously? Use the reaction below to assist with your reasoning.
2H2(g) + O2(g) ⟶ 2H2O(g)
That makes no sense. Hydrogen balloons should explode even more at higher temperatures.
Combustion of H2 gas has a negative entropy and therefore an upper limit for the temperature at which the reaction can occur
Combustion of H2 has a negative enthalpy and therefore an upper limit for the temperature at which the reaction can occur.
Combustion of H2 does work on the system and therefore an upper limit for the temperature at which the reaction can occur.
QT 4.17
What are the signs of ΔG, ΔH, and ΔS for water condensing at 105℃?
H2O(g) ===> H2O(l)
+, ─, ─
─, ─, ─
+, +, +
─, +, ─
QT 4.12
Using bond enthalpy data, calculate the changes in enthalpy for the following reaction.
CH4 (g) + 2 O2 (g) → CO2 (g) + 2 H2 O (g)
Various bond energies:
C-H 400 𝑘𝐽 ∙ 𝑚𝑜𝑙-1
O=O 500 𝑘𝐽 ∙ 𝑚𝑜𝑙-1
C=O 800 𝑘𝐽 ∙ 𝑚𝑜𝑙-1
O-H 450 𝑘𝐽 ∙ 𝑚𝑜𝑙-1
-800 𝑘𝐽 ∙ 𝑚𝑜𝑙-1
+800 𝑘𝐽 ∙ 𝑚𝑜𝑙-1
-350 𝑘𝐽 ∙ 𝑚𝑜𝑙-1
-500 𝑘𝐽 ∙ 𝑚𝑜𝑙-1
QT 4.12
Which of the following statements about bond energy calculations is NOT true?
They are a way to calculate heats of reaction
They do not consider intermolecular force interactions
The calculation involves summing the reactant bond energies and subtracting the
product bond energies
The table of bond energies includes multiple values for the same bond energy
QT 4.17
You are making a plaster of Paris cast of a footprint at a crime scene and notice that the
plaster of Paris has become quite warm when water is added. What would you predict as
the temperature dependence for the chemical reaction? The balanced equation is shown
below.
CaO (s) + H2 O(g) --> Ca(OH)2(s)
This reaction occurs at any temperature.
This reaction does not occur at any temperature.
This reaction is more likely to occur at higher temperature.
This reaction is more likely to occur at lower temperature.
