CHEM TEST 4 MULTIPLE CHOICE:
Which reaction produces a decrease in the entropy of the system? CaCO3 (s)→CaO(s) + CO2 (g) 2C(s) + O2 (g)→2CO(g) CO2 (s)→CO2 (g) 2H2 (g) + O2 (g)→2H2O(l) e. H2O(l)→ H2O (g)
2H2 (g) + O2 (g)→2H2O(l)
A reaction that is not spontaneous at low temperature can become spontaneous at high temperature if Delta H is ____ and Delta S is ___. A. +,+ B. -,- C. +,- D. -,+
A
If Delta G for a reaction if greater than zero, then _____. A. K < 1 B. K = 1 C. K > 1 D. K = 0 E. More information is needed
A
What is the oxidation number of nitrogen in HNO3? A. +5 B. -1 C. +1 D. +3 E.+7
A
Which transformation could take place at the cathode of an electrochemical cell? A. HSo4- to H2SO3 B. MnO2 to MNO4- C. Mn2+ to MnO4- D. Br2 to BrO3- E. No to HNO2
A
Which element is oxidized in the reaction below? Fe^ 2 H Cr2O7^-2 --> Fe^ 3 Cr^ 3 H2O A. NO2 B. HNO3 C. H2O D. S E. Fe2S3
B
Consider a pure crystalline solid that is heated from absolute zero to a temperature above the boiling point of the liquid. Which of the following processes produces the greatest increase in the entropy of the substance? A. heating the liquid B. heating the gas C. heating the solid D. vaporizing the liquid E. melting the solid
D
One of the differences between a voltaic cell and an electrolytic cell is that in an electrolytic cell ______ A. a non-spontaneous reaction is forced to occur B. oxidation occurs at the cathode C. electrons flow toward the anode D. an electric current is produced by a chemical reaction E. O2 gas is produced at the cathode
D
The thermodynamic quantity that expresses the degree of disorder in a system is A. bond energy B. heat flow C. internal energy D. entropy E. enthalpy
D
Consider an electrochemical cell based on this reaction: 2H+ (aq) + Sn(s) --- Sn2+ (aq) + H2 (g) Which of the following actions would change the measured cell potential? A. increasing the pressure of hydrogen gas in the cathode compartment B. lowering the pH in the cathode compartment C. increasing the pH in the cathode compartment D. increasing the [Sn2+] in the anode compartment E. Any of the above will change the measured cell potential
E
The entropy of the universe is _______. A. constant B. the same as the energy, E C. zero D. continually decreasing E. continually increasing
E
When a system is at equilibrium: A. both forward and reverse processes have stopped B. the reverse process is spontaneous but the forward process is not C. the forward process is spontaneous is spontaneous but the reverse is not D. the forward and the reverse processes are both spontaneous E. the process is not spontaneous in either direction
E
Which of the following processes produces a decrease of the entropy of the system? A. dissolving sodium chloride in water B. sublimation of naphthalene C. boiling of alcohol D. explosion of nitroglycerine E. dissolving oxygen in water
E
With thermodynamics, one cannot determine
speed of the reaction
