ch17-18
A standard electrochemical cell is constructed from an anode that has a standard reduction potential of -2.0V and a cathode that has a standard reduction potential of +0.5V. which of the following is the correct expression to calculate the standard cell potential?
+0.5+2.0
Ca_{(s)}+Mg^{2+}_{(aq)}->Ca^{2+}_{(aq)}+Mg_{(s)}, E^O=0.50V and Mg^{2+}_{(aq)}+2e^- -> Mg_{(s)}, E^O=-2.37V Using the standard cell potential given above and the standard reduction potential listed above, calculate the reduction potential of the 1/2 reaction Ca^{2+}_{(aq)}+2e^- -> Ca_{(s)}
-2.78V
Given that the standard potential for the 1/2 reaction Ca^{2+}_{(aq)}+2e^- -> Ca_{(s)} -s -2.87V, what is the standard potential for the 1/2 reaction 2Ca^{2+}_{(aq)}+4e^- -> 2Ca_{(s)}?
-2.87V
a reaction taking place at 100degC has an entropy change of 200J/K and an enthalpy change of -20kJ. Which of the following expressions would be used to calculate DeltaG under these conditions?
-20000-373*200
Which of the following electrochemical reactions will favor the formation of products at equilibrium?
.... 0.89V ; ...1.6V
Without regard to balancing oxygen and hydrogen atoms, identify the missing coefficients in the 1/2 reaction __ S_2O_8^{2-}_{(aq)}->___SO_4^2-_{(aq)}
1 ; 2
What are the 3 methods to determine equilibrium constants?
1. From concentration data: K=\frac{[C]^c[D]^d}{[A]^a[B]^b} ; 2. From thermochemical data: ln(K)=\frac{-DeltaG^O}{RT} ; 3. Electrochemical data: E^O=\frac{RT}{nF}*ln(K) or ln(K)=\frac{nFE^O}{RT}
Corrosion prevention methods
1. Galvanization (the coating of iron with zinc) ; 2. Cathodic protection: instead of coating the entire surface of the first metal with a second metal, the second metal is placed with the electrical contact with the first metal - attaching a magnesium stake to iron will corrode the magnesium instead of the irons and acts as a sacrificial anode
Place the following steps for balancing a redox reaction that occurs in acidic solution in the correct order. Start with the first step at the top of the list.
1. Write the unbalanced equation in ionic form ; 2. Separate the unbalanced reaction into half-reactions ; 3. Balance each 1/2 equation with regard to atoms. Add H_2O to each half-reaction as needed to balance oxygen, and add H^+ as needed to balance hydrogen ; 4. Balance the charges in each half-reaction by adding electrons here appropriate ; 5. Multiply the balanced half-reactions by the appropriate factors to set the number of electrons each side to be equal to each other ; 6. Add the two 1/2 reactions together and cancel any identical terms that appear on both sides.
Calculate the value of DeltaG for a action at 75degC whose enthalpy change is 50 kJ and whose entropy change is 100 J/K
15.2 kJ
Identify the missing coefficient to balance Mn in the following half-reaction (do not worry about balancing the oxygen atoms. Mn_2O_3->____MnO_2
2
Which of the following are true when the reactions below are added together? Reaction 1: 2BiO^++4H^++6e^- ->2Bi+2H_2O ; Reaction 2: 6H_2O->3H_2O_2+6H^++6e^-
2 moles of H^+ appear as a product ; 4 moles of H_2O appear as a reactant
When hydrogen and oxygen atoms are balanced in the following 1/2 reaction under acidic conditions, which of the following statements are correct? HClO_{(aq)}->Cl_{2(g)}
2 moles of H^+ appear as a reactant ; 2 moles of H_2O appear as a product
Which of the following 1/2 reactions could occur at the cathode of galvanic cell?
2H^+_{(aq)}+2e^- -> H_{2(g)} ; Ni^{2+}_{(aq)}+2e^- -> Ni_{(s)}
What is the spontaneous reaction that occurs when the following 1/2 cells are combined? Zn^{2+}_{(aq)}+2e- -> Zn_{(s)}, E^O=-0.76V and Na^+_{(aq)}+e^- -> Na_{(s)}, E^O=-2.71V
2Na_{(s)}+Zn^{2+}_{(aq)} -> 2Na^+_{(aq)}+Zn_{(s)}
Identify the number of electrons required to balance the following 1/2 reaction. Also indicate whether these electrons must appear as reactants or products. H^++PbSO_4->Pb+HSO_4^-
2e^- ; reactant
When hydrogen and oxygen atoms are balanced in the following 1/2 reaction under acidic conditions, which of the following statements are correct? TiO_{2(s)}->Ti_{(s)}
4 moles of H^+ appear as a reactant ; 2 moles of H_2O appear as a product
How many moles of electrons are transferred in the electrochemical reaction represented by the balanced equation 3Mn_{(s)}+2Au^{3+}_{(aq)}->3Mn^{2+}_{(aq)}+2Au_{(s)}
6
Which of the following options correctly describe the standard hydrogen electrode (SHE)?
A platinum electrode is immersed in a 1 M solution of aqueous HCl ; hydrogen gas at a pressure of 1 atm is bubbled through the solution
What is a spontaneous process?
A process that occurs under specified conditions without continuous input of energy
which statement correctly describes the relationship between the entropy and spontaneity of a process?
A reaction/process will be spontaneous if DeltaS_{sys}>0 and DeltaS_{surr}>0
Which of the following options correctly describe the shorthand notation used to represent an electrochemical cell?
A single vertical line in cell notation represents a phase boundary ; the anode is written first, on the left side of the cell notation
Which of the following statements about oxidation, reduction, and oxidizing/reducing agents are correct?
A species whose oxidation number increases is acting as a reducing agent ; a species that gains electrons is acting as a oxidizing agent ; a species that loess electrons is oxidized
Galvanic (Voltaic) Cell
A spontaneous chemical reaction which generates an electric current
If we were to solve for the cell potential of the following reaction, which 2 reactions would we first need to find in a standard reduction table? 2Ag^+_{(aq)}+Zn_{(s)}->2Ag_{(s)}+Zn^{2+}_{(aq)}
Ag^+_{(aq)}+e^- ->Ag_{(s)} ; Zn^{2+}_{(aq)}+2e^- -> Zn_{(s)}
Electrolytic Cell
An electric current which drives a non spontaneous reaction
For a chemical process, how is enthalpy change of the system (DeltaH_{sys}) related to the entropy change of the surroundings (DeltaS_{surr})?
An exothermic reaction will result in an increase in the entropy of the surroundings.
In a galvanic cell, electrons are generated due to the oxidation reaction at the _____, and flow through the external circuit toward the ____.
Anode ; cathode
The electrode at which the oxidation reaction occurs is called the ____, while the electrode at which the reduction reaction occurs is called the _____.
Anode ; cathode
The standard potential of an electrochemical cell is determined by subtracting the standard reduction potential of the ___ from the standard reduction potential of the ____. The 1/2 reaction at the cathode will be the 1/2 reaction whose standard reduction potential is more ______.
Anode ; cathode ; positive
After separating a redox reaction into its half-reactions, the next step in balancing is to ____.
Balance the number of atoms other than oxygen and hydrogen
Example of a galvanic cell is...
Battery
Based on the data shown, match each substance with its ability to act as an oxidizing agent; Br_{2(l)}+2e^- -> 2Br^-_{(aq)}, E^O=+1.07V ; Na^+_{(aq)}+e^- -> Na_{(s)}, E^O=-2.71V ; Zn^{2+}_{(aq)}+2e^- -> Zn_{(s)}, E^O=-0.763V
Br_2 — strongest oxidizing agent ; Na^+ — weakest oxidizing agent ; Zn — will not act as an oxidizing agent
In a galvanic cell, positive charges ions migrate from the salt bridge to the ____ compartment, while negatively charges ions migrate from the salt bridge to the _____ compartment.
Cathode ; anode
Identify the 1/2 reactions that occur at the cathode and the anode in the overall redox reaction Fe^{3+}_{(aq)}+Cu_{(s)}->Cu^+_{(aq)}+Fe^{2+}_{(aq)}
Cathode — Fe^{3+}_{(aq)}+e^- ->Fe^{2+}_{(aq)} ; anode — Cu_{(s)}->Cu^+_{(aq)}+e^-
The standard cell potential may be solved using the equation nE^O_{______} - E^O_{________}. Select all the options that will correctly complete the equation given.
Cathode, anode ; reduction, oxidation
Which of the following must be known in order to assess the spontaneity of a chemical reaction/physical process at a particular set of conditions?
Change in entropy ; change in enthalpy ; reaction temperature
Electrochemistry is the study of the relationship between ____ energy and ______ energy.
Chemical ; electrical
Standard hydrogen electrode (S.H.E.)
Chosen reference electrode
Electrochemistry...
Deals with situations where oxidation and reduction reactions are separated in space or time, connected by an external electric circuit
How is the change in free energy (DeltaG) of a chemical system related to work?
DeltaG represents the maximum useful work that a reaction can supply
Cell potentials and free-energy changes for cell reactions
DeltaG=-nFE or DeltaG^O=-nFE^O where n=number of moles of electrons transferred in the reaction and E=cell potential
Which of the following options correctly expresses the relationship between free-energy change and cell potential?
DeltaG=-nfE_{cell}
Under equilibrium conditions, the equation DeltaG=DeltaG^O+RTlnQ simplifies to which of the following?
DeltaG^O=-RTlnK
Match the values of DeltaG^O with associated equilibrium constants. (Note that all DeltaG^O values are rounded to 1 sig fig)
DeltaG^O=0 — K=1; DeltaG^O=+100kJ — K=3*10^{-18} ; DeltaG^O=-100kJ — K=3*10^{17}; DeltaG^O=-10kJ — K=5*10
Match each thermodynamic quantity with the information it provides about a given reaction.
DeltaG^O>0 — reactants are favored at equilibrium ; DeltaG>0 — reactions will occur spontaneously ; DeltaG<0 — reaction will be non-spontaneous ; DeltaG^O<0 — products are favored at equilibrium
Match the sign of DeltaG^O with the direction of the reaction that is favored for a system at equilibrium.
DeltaG^O>0 — reactants are favored at equilibrium ; DeltaG^O<0 — products are favored at equilibrium
Which of the following symbols denotes a standard free-energy change of reaction?
DeltaG^o_{rxn}
Match each free-energy term with its correct definition
DeltaG_{rxn} — the free-energy change for the reaction under any conditions ; DeltaG^O_{rxn} — the free-energy change for the reaction under standard conditions
a reaction is found to be spontaneous only above a particular temperature. Which of the following must be true?
DeltaH^O_{rxn}>0 ; DeltaS^O_{rxn}>0
Which of the following options correctly show how to calculate the entropy change of a system?
DeltaS=k*ln(\frack{W_f}{W_i}) ; DeltaS=S_f-S_i
With regard to species on a table of standard reduction potentials, the ______ rule states that any substance on the left hand side of a 1/2 reaction will react with any substance below it on the right hand side.
Diagonal
The standard reduction potential for the 1/2 reaction Mn^{2+}_{(aq}+2e^- -> Mn_{(s)} is -1.18V. What is the effect of the reduction potential of doubling all of the coefficients of the 1/2 reaction?
Doubling the coefficients has no effect on the reduction potential
Non spontaneous reaction dependent on E and DeltaG happens when
E<0 ; DeltaG>0 ; electrolytic cell
Equilibrium reaction dependent on E and DeltaG happens when
E=0 ; DeltaG=0 ; dead battery
Nerst Equation
E=E^O-\frac{0.0592V}{n}*log(Q) in volts at 25^OC
Spontaneous reaction dependent on E and DeltaG happens when
E>0 ; DeltaG<0 ; galvanic cell
Standard cell potentials and equilibrium constants
E^O=\frac{0.0592V}{n}*log(K) in volts at 25^OC
Match each cell potential with its implication for the extent of reaction at equilibrium.
E^O_{cell}>0 — products are favored at equilibrium ; E^O_{cell}<0 — reactants are favored at equilibrium
Coulomb (C)
Electric charge
The first law of thermodynamics states that _____ is always conserved.
Energy
In order to asses the spontaneity of a chemical reaction or physical process both the change in _______ and ___________ associated with the reaction or process must be known.
Enthalpy ; entropy
the second law of thermodynamics sates that the total _____ of the universe will ______ for any spontaneous process
Entropy ; increase
In order to balance the 1/2 reactions (below) to each other, what operation must be performed? Equation 1: 2H_2O->O_2+4H^++4e^- ; Equation 2: Ni^{2+}+2e^- ->Ni
Equation 2 multiplied by 2
In order to balance the 1/2 reactions (below) to each other, what operation must be performed? Equation 1: PtCL_4^{2-}+2e^- -> Pt+4Cl- ; Equation 2: Cr->Cr^{3+}+3e^-
Equation 2 multiplied by 2 ; equation 1 multiplied by 3
True/false: for a spontaneous redox reaction, the products are stronger oxidizing and reducing agents than the reactants
FALSE
True/false: for an element in its standard state, the standard entropy S^o is equal to 0 J/mol K
FALSE
the entropy change for a process is claculated from the equation DeltaS=S_{______}-S_{_________}
Final ; initial
The ______ law of thermodynamics states that _____ can neither be created nor destroyed
First ; energy
the Gibbs ____ energy change (symbolized by Delta____) is a measure of the spontaneity of a process, and of the useful energy available from it.
Free ; G
The standard hydrogen electrode (SHE) is assembled by immersing a piece of platinum in a 1.00 M acid (H^+) solution in the presence of 1.00 atm H_2 gas. Identify the role played by each component o this cell.
H^+_{(aq)} — reactant in reduction half-cell ; H_{2(g)} — product in reduction half-cell ; Pt_{(s)} — electrode
To which f the following 1/2 reactions must 2 electrons appear as products in order to balance the equation?
H_2+1OH^- ->2H_2O ; H_2O+PbO-.PbO_2+2H^+
When a redox reaction takes place in an acidic solution involves oxygen imbalance, oxygen should be balanced by adding _____ as needed, while hydrogen should be balanced by adding _____.
H_2O ; H^+
For the chemical reaction shown below, which of the following (unbalanced) reactions should be used the starting point for the reduction half-reaction? 2Na+2H_2O->2NaOH+H_2
H_2O->H_2
Match each symbol in the cell notation shown below with its correct meaning. Pb_{(s)} I Pb^+ (1 M) II Co^{3+} (1 M) I Co_{(s)}
I — phase boundary ; II — salt bridge ; Pb_{(s)} — anode ; Co_{(s)} — cathode
which of the following statements are correct about the meaning of the signs of DeltaG and DeltaG^O?
If DeltaG^O>0, the reaction favors reactants at equilibrium ; if DeltaG<0, the reaction will occur spontaneously
which statements about the relationship between Q, K, and DeltaG are correct?
If Q>K, the value of DeltaG will decrease as the reaction proceeds ; if Q<K, then the value of DeltaG<0
An exothermic reaction releases heat to the surroundings, causing a(n) ____ in the movement of the particles in the surroundings. The entropy of the surroundings will therefore _______.
Increase ; increase
the change in entropy for a given process can be calculated by subtracting the ______ entropy of the system from the ________ entropy of they system
Initial ; final
Standard potential of a cell
Is the same of the standard 1/2-cell potentials for oxidation at the anode and reduction at the cathode ; E_{cell}^O=E_{ox}^O+E_{red}^O
By the definition, if 1 coulomb of charge passes between 2 electrodes that differ in potential by 1V, 1 _______ of energy is released. This relationship is correctly expressed as V=_______ per ________
J ; J ; C
When a reaction is at equilibrium, the reaction quotient Q is always equal to ____ and DeltaG is equal to ______.
K ; 0
According to the diagonal rule, any species on the _______ of a given 1/2 cell reaction will react with a species on the ____ of any 1/2 cell reaction located below it. (Assume that the table of standard reduction potentials lists the most positive reduction potential at the top)
Left ; right
If a given process proceeds spontaneously toward the products, the value of the reaction quotient Q is ____ the equilibrium constant K, and DeltaG for the reaction will be _______.
Less than ; negative
When writing a spontaneous redox reaction from 2 1/2 reactions in a table of standard reduction potentials, the 1/2 reaction occurring at the anode will be the 1/2 reaction whose reduction potential in the table is _______ positive. In the spontaneous reaction, the direction of this 1/2 will be _____ its direction in the table.
Less, reversed from
Oxidation involves the _____ of electrons, while reduction involves the _____ of electrons.
Loss ; gain
The redox reaction below is spontaneous as written. Which statement about the relative roles and strengths of the components of the reaction is correct? Mg_{(s)}+2Cu^+_{(aq)}->Mg^{2+}_{(aq)}+2Cu_{(s)}
Mg^{2+} is the weaker oxidizing agent
In order to balance the 1/2 reactions (below) to each other, what operation must be performed? Equation 1: MnO_2+4H^++2e^- -> Mn^{2+}+2H_2O ; Equation 2: Cu+I^- ->CuI+e^-
MnO_2+4H^++2Cu+2I^- ->Mn^{2+}+2CuI+2H_2O
Match each half-reaction with the number and position of water molecules needed to balance it.
MnO_{2(s)}->Mn^{2+}_{(aq)} — 2, product side ; 2Cr^{3+}_{(aq)}->Cr_2O_7^-_{(aq)} — 7, reactant side ; H_2SO_{3(aq)}->HSO_4^-_{(aq)} — 1, reactant side ; VO_2^+_{(aq)}->VO^{2+}_{(aq)} — 1, product side
If a given reversible reaction has positive values for both DeltaH and DeltaS, the value of DeltaG will become ____ negative as temperature increases, and the formation of the ______ will be increasingly favored.
More ; products
In which of the following (unbalanced) 1/2 reactions will 1 mole of water appear as a reactant when oxygen atoms are balanced?
N_1O_5->2NO_3 ; Na->NaOH
The larger the equilibrium constant K for a reaction, the more ____ the value of DeltaG^O and the more the _____ are favored at equilibrium.
Negative ; products
Given the 2 1/2 reactions below, which reaction will be the reduction reaction in the spontaneous reaction that would occur between them? Cr^{3+}+3e^- -> Cr, E^O=-0.74V and Ni^{2+}+2e^- -> Ni, E^O=-0.28V
Ni^{2+}+2e^- -> Ni
Given the following reaction, classify each species according to its ability to act as an oxidizing/reducing agent. Ni^{2+}_{(aq)}+2e^- -> Ni_{(s)}
Ni^{2+}_{(aq)} — oxidizing agent ; Ni_{(s)} — reducing agent
Which of the following must be balanced in order to balance a redox reaction?
Number of atoms of each type ; overall charge
A spontaneous process...
Occurs under a given set of conditions
When predicting the spontaneous reaction between two different 1/2 cells, the reaction with the most negative cell potential will be the ______ reaction, while the reaction with the most positive cell potential will be the ____ reaction.
Oxidation ; reduction
If a substance causes another substance to be oxidized, that substance is a(n) ______ agent. Likewise, the substance that is oxidized in an electrochemical reaction is always the _____ agent.
Oxidizing ; reducing
A voltaic cell is constructed from the 2 1/2 reactions whose standard reductions potentials are shown. What reaction will occur at the anode? Pb^{2+}+2e^- -> Pb, E^O=-0.13V and Co^{3+}+3e^- -> Co, E^O=+1.57V
Pb->Pb^{2+}+2e^-
The measure of energy is used in electrochemistry is the cell ______ (E_{cell}), which is the difference in electrical potential between two electrodes. A common term for this diffuse in electrical potential is _______ force or emf.
Potential ; electromotive
Analytical electrochemistry
Potentiometry ; voltammetry
If a substance acts as a strong reducing agent, it will appear on a table of standard reduction potentials as the ____ in a 1/2 reaction with a ___ standard reduction potential.
Product ; negative
Consider the 1/2 reaction with the most negative standard reduction potential in a given table. The ______ in that 1/2 reaction will be the strongest _____ agent among the substances in the table.
Product, reducing
For a chemical reaction, DeltaS^O_{rxn}=\sum{nS^O(_______)}-\sum{nS^O(________)}
Products ; reactants
Based on the equation DeltaG=DeltaG^O+RTln(Q), match each range of Q values to the correct relationship between the magnitudes of DeltaG and DeltaG^O. (Recall that the sign indicates whether change is into (positive) or out of (negative) the system. Therefore, focus on the magnitudes of the values for the free energies, not their signs).
Q=1 — DeltaG=DeltaG^O ; Q<1 — DeltaG>DeltaG^O ; Q>1 — DeltaG<DeltaG^O
If a substance acts as a strong oxidizing agent, it will appear on a table of standard reduction potentials as the ____ in a 1/2 reaction with a ___ standard reduction potential.
Reactant ; positive
a reaction with a positive value of DeltaG^O will favor _____ at equilibrium, while a reaction with a negative value of DeltaG^O will favor ____ at equilibrium
Reactants ; products
The standard _____ potential for a 1/2 reaction is the voltage associate with the reduction reaction at an electrode when all solutes are at a concentration of 1 M and gases are at _____ atm of pressure.
Reduction ; 1
Standard potentials for electrochemical 1/2 reactions are expressed as ______ potentials. They measured at a standard temperature of _______degC
Reduction ; 25
Which of the following options correctly describes how to use a table of standard reduction potentials to write the reaction for the 1/2 reaction that occurs at the anode?
Reverse the appropriate reduction 1/2 reaction
Volt (V)
SI unit of electrical potential
Joule (J)
SI unit of energy
given the balanced chemical equation CH_{4(g)} + 2O_{2(g)} —> CO_{2(g)} + 2H_2HO_{(g)}, which of the following equations should be used to calculate the total entropy change for this? (States of matter have been omitted for simplification)
S[CO_2]+2(S[H_2O])-S[CH_4]-2(S[O_2])
Match each component of a galvanic cell with its correct description.
Salt bride — allows the balancing of charges between the two compartments ; anode compartment — where oxidation 1/2 reaction occurs ; cathode compartment — where the reduction 1/2 reaction occurs
which changes in state will result in an increase in the entropy of a substance?
Solid to vapor ; liquid to vapor ; solid to liquid
A(n) ________ process is one that will occur without a continuous input of energy under a given set of conditions.
Spontaneous
If DeltaG^O<0, the reaction is ______ as written; if K<1, the reaction is ______ as written
Spontaneous ; non spontaneous
in order to calculate the entropy change of a reaction using tabulated values, which of the following are necessary?
Standard entropies of all components of the reaction ; a balanced equation
Which of the following statements correctly describe standard electrode potentials?
Standard reduction potentials are measured for solutes at 1 M and gases at 1 atm ; by convention, standard electrode potentials are quoted as reduction potentials
In order to determine the spontaneity of a reaction or process, the entropy changes in both the _____ and _______ must be considered in order to evaluate DeltaS_{univ}
System ; surroundings
Electrochemistry
The area of chemistry concerned with the interconversion of chemical and electrical energy
Which of the following statements correctly describe tabulated standard electrode potentials?
The best oxidizing agents will be reactants in 1/2 reactions with the most positive cell potentials ; if E^O for a given 1/2 reaction is large and positive, the reaction favors the products from left to right as written
Which of the following best explains why the following chemical reaction is not balanced? Cu^{2+}_{(aq)}+Fe_{(s)}->Cu_{(s)}+Fe^{3+}_{(aq)}
The charge is not balanced
Faraday constant
The charge on 1 mol of electrons (96,500 C/mol e^-)
Anode
The electrode where oxidation occurs ; the electrode where electrons are produced ; is what anions migrate toward ; has a negative sign
cathode
The electrode where reaction occurs ; the electrode where electrons are consumed ; is what cations migrate toward ; has a positive sign
which of the following is a correct description of the third law of thermodynamics?
The entropy of a perfect crystalline substance is 0 at 0K
Electromotive force (emf) or cell potential (E) or cell voltage
The force or electrical potential that pushes the negatively charged electrons away from the anode (- electrode) and pulls them toward the cathode (+ electrode)
which of the following options correctly explain the impact of DeltaH_{sys} on the entropy change of the surroundings?
The lower the temperature, the greater the effect of DeltaH_{sys} on the entropy of the surroundings ; at high temperature, the enthalpy change of the system will have a relatively small effect on the entropy of the surroundings
Corrosion
The oxidative deterioration of a metal
Electrolysis
The process of using an electric current to bring about chemical change
As the reaction quotient Q increases, what is the effect on the spontaneity of the reaction?
The reaction becomes less spontaneous
Match the prediction of the spontaneity of a given process with the appropriate combination of DeltaH and DeltaS values
The reaction is always spontaneous if — DeltaH<0 and DetaS>0 ; the reaction is always non-spontaneous if — DeltaH>0 and DeltaS<0 ; the reaction is spontaneous only at low T if — DeltaH<0 and DeltaS<0 ; the reaction is spontaneous only at high T if — DeltaH>0 and DeltaS>0
Consider the chemical reaction K^+_{(aq)}+OH^-_{(aq)}->KOH_{(s)}, for which DeltaH^O=+57.7 kJ/mol and DeltaS^O=-12.7 J/K. Which statement correctly describes the effect of temperature on the spontaneity of this reaction?
The reaction is not spontaneous under any temperature conditions.
Which of the following options correctly describe the behavior of a reversible reaction for which both DeltaH and DeltaS<0?
The reaction will become less spontaneous as the temperature increases ; at low temperatures, DeltaG_{rxn}<0 ; the formation of the reactants will become increasingly favored as the temperature rises
Consider the chemical reaction 2SO_{3(g)} -> O_{2(g)}+2SO_{2(g)}, for which DeltaH^O=+198.4kJ and DeltaS^O=+187.9j/K. Which of the following statements correctly describe the effect of temperature on the spontaneity of this reaction?
The reaction will become more spontaneous as the temperature increases ; the reaction is spontaneous only at higher temperatures
Which of the following options correctly describe standard entropy?
The standard entropy of a substance is its absolute entropy at 1 atm ; the uits of standard entropy is J/mol K
Which of the following options correctly identify the abbreviation for cell potential and its units?
The unit of cell potential is the volt, symbol V ; the symbol for cell potential is E
Which of the following options correctly describe the units used to express electrical potential, charge, and electrical energy?
The volt is the unit for electrical potential ; electrical energy can be measured in joules
The cell potential of a galvanic cell is ______.
The voltage across the 2 electrodes
In the diagram, electrons flow from the ____ electrode to the _____ electron. Cations flow from the ____ cell to the ____ cell.
Zn ; Cu ; anode ; cathode
which of the following is an application of the second law of thermodynamics?
a gas expands because matter tends to spread out
Which of the following statements correctly describe the effects of temperature of the spontaneity of a reaction?
a reaction with a negative value of DeltaS will become less spontaneous with increasing temperature ; a reaction with a positive value of DeltaH will become more spontaneous with increasing temperature
For a table of standard reduction potentials that is listed with the most positive cell potentials at the top of the list, any species on the left of a given 1/2 cell reaction will react spontaneously with a species that appears on the right of any 1/2 cell reaction located ______ it.
below
the third law of thermodynamics states that a perfect ___ of a pure solid substance has _____ entropy at a temperature of 0 K.
crystal ; 0
The standard _______ electrode is used as a reference cell to determine standard reduction potentials. By definition, the reduction potential of this electrode is 0.00V.
hydrogen
1/2 cell potentials are ______ properties
intensive
A species acts as a(n) ______ agent if it gains electrons in a 1/2 reaction. Conversely, it could potentially act as a(n) ____ agent if it loses electrons in a 1/2 reaction.
oxidizing ; reducing
As listed in a table of standard electrode potentials, the reactants in the 1/2 reactions are potential _____ agents, while the products of the 1/2 reactions are potential ___ agents.
oxidizing ; reducing
If a substance gains electrons in a reaction, it is acting as a(n) ____ agent. If a substance loses electrons in a reaction, it is acting as a(n) _____ agent.
oxidizing ; reducing
In a table of standard reduction potentials, the reactants are a list of potential _____ agents, while the products are a list of potential ____ agents.
oxidizing ; reducing
The ____ law of thermodynamics states that a spontaneous process will result in an increase in the entropy of the universe.
second
The gibbs free energy change DeltaG allows us to determine the spontaneity of a process based on thermodynamic changes to the ____.
system only
Which of the following options correctly describe the Gibbs free energy change (DeltaG) of a system?
the free energy change for a process is a measure of the useful work it can provide ; DeltaG is a measure of the spontaneity of a process
which of the following statements correctly explain the increase in entropy that occurs when a substance changes from a solid to liquid, or liquid to gas?
the freedom of movement of the particles increases in the change of solid to liquid to gas ; the energy of the particles increases during these phase changes
Select which phase change, melting or vaporization, will have a greater increase in entropy for a given substance. In addition, select the statement(s) that explain(s) why.
the mobility of the particles increases much more when this phase change occurs ; vaporization of a substance
Which of the following are the focus of electrochemistry?
the relationship between chemical change and electrical work ; the interconversion of electrical and chemical energy
a given process will be spontaneous if the entropy change of the ____ for the process is greater than 0.
universe
The total free energy (DeltaG) for a given process represents the maximum amount of ________ that can be done by the process.
work
