When ignited, solid ammonium dichromate decomposes in a fiery display. This is the
reaction for a “volcano” demonstration. The decomposition produces nitrogen gas,
water vapor, and chromium(III) oxide. The temperature is constant at 25°C
Determine Suniv° (in kJ/mol K).
A) 7.66
B) 6.39
C) 84.3
D) 5.22
E) 6.03
Calculate the [H+] in a solution that has a pH of 8.73.
A) 1.9 x 10-9M
B) 5.4 x 10-6M
C) 8.7 x 10-9M
D) 9.4 x 10-1M
E) 7.2 x 10-1M
A wavelength of red light is measured at 655 nm. What is this measurement in cm?
A)6.55 cm C)6.55 x 10-5cm
B)0.00655 cm D)6.55 x 10-7cm
For which of the following reaction(s) is the enthalpy change for the reaction not equal
to DHf° of the product?
I.2H(g) –> H2(g)
II.H2(g) + O2(g) –> H2O2(l)
III.H2O(l) + O(g) –> H2O2(l)
A)I
B)II
C)III
D)I and III
E)II and III
Refer to the galvanic cell below (the contents of each half-cell are written beneath each
compartment):
The standard reduction potentials are as follows:
What is the value of cell?
A) -0.176
B) 2.836
C) 0.176
D) 0.676
E) 6.200
Which best explains the following trend?
Element b.p. (K)
He 4
Ne 25
Ar 95
Kr 125
Xe 170
A)London dispersion forces
B)dipole–dipole interaction
C)hydrogen bonding
D)Le Chatelier’s principle
E)none of these
The following questions refer to the reaction between nitric oxide and hydrogen
What are the units for the rate constant for this reaction?
A)L/mol·s
B)L2/mol2·s
C)mol/L·s
D)s-2
E)L-2
Which of the following are true at equilibrium for the reaction A D B?
I. [A] is no longer changing.
II. The overall rate of change of [B] is zero.
III. No new molecules of A are converting into B.
IV. The value of [B]/[A] is changing in time.
A) I, II, III
B) I, II
C) I, II, IV
D) I, IV
E) II, III
What is the pH for a buffer that consists of 0.45 M CH3CH2COOH and 0.10 M
CH3CH2COOK? Kaof CH3CH2COOH = 1.3 x 10-5
A)
Consider the following information about the diprotic acid, ascorbic acid. (H2As for
short, molar mass 176.1)
H2As HAs–+ H+pKa= 4.10 (Ka= 7.9×10-5)
HAs– As2-+ H+pKa= 11.79 (Ka= 1.6×10-12)
The titration curve for disodium ascorbate, Na2As, with standard HCl is shown below:
Which of the following is a major species present at point IV?
A) H2As
B) HAs–
C) As2-
D) H+
E) none of these
Identify the precipitate(s) formed (if any) in the following reaction in aqueous solution,
Fe(NO3)2+ (NH4)2CO3 –>
A)Fe2(CO3)3
B)FeCO3(s)
C)(NH4)2CO3(s)
D)NH4NO3(s)
E)No precipitate will be observed
What is the pH for a buffer that consists of 0.25 M CH3CH2COOH and 0.10 M
CH3CH2COONa? Kaof CH3CH2COOH = 1.3 x 10-5
A)
How many electrons are transferred in the balanced reaction (i.e., what will be the value
of n in the Nernst equation)?
A) 5
B) 6
C) 30
D) 22
E) 2
A certain complex ion has a distorted octahedral structure in which the ligands along
the plus and minus z axes are compressed (pushed in closer to the central metal ion).
The d orbital splitting diagram for this complex ion would be:
Calculate the mole fraction of NaCl in a solution prepared by dissolving 117 g NaCl in
1.15kg H2O.
For the reaction P4O10(s) + 6H2O(l) –> 4H3PO4(aq), what mass of P4O10must be
consumed if 3.71 ´ 1023molecules of H2O are also consumed?
The concentration of C after 10.0 minutes is
The initial rate of production of NO2for this reaction is approximately