Download 1) Which of the following correctly lists the atoms in order of

Chemistry 112
Exam 2, Form A
1) Which of the following correctly lists the atoms in order of increasing size (smallest to largest)?
a) F< K < Ge < Br < Rb
b) F < Br < Ge < K < Rb
c) F < Ge < Br < K < Rb
d) F < K < Br < Ge < Rb
e) F < Br < Ge < Rb < K
2). The first six ionization energies for an element are: 786 kJ, 1580 kJ, 3230 kJ, 4360 kJ, 21400 kJ,
and 25780 kJ. This element has __________ valence electrons.
a) 1
b) 2 c) 3 d) 4 e) 5
3). Consider the reaction: C2H5OH(l) + 3 O2(g) → 2 CO2(g) + 3 H2O(l). In this reaction, the reactant
C2H5OH is ______________ and contains C with _____________ oxidation number.
a) being oxidized, +2
b) the reducing agent, −2
c) being reduced, +4
d) the oxidizing agent, −2
e) the oxidizing agent, +4
4). The reaction, 4 Al(s) + 3 O2(g)→2 Al2O3(s) ∆H = −3351 kJ is __________ so heat is
________________ by the reaction.
a) endothermic, evolved b) endothermic, absorbed
c) exothermic, evolved
d) exothermic, absorbed
5). An X2+ ion has an excited electron configuration: [Ar]4s23d95p1. Identify the neutral element.
a) Ge
b) In
c) Ga
d) Zn
e) Cd
6).
A 5.0 mol gas sample at 1.0 atm is expanded at constant temperature from 10.0 L to 15.0 L. The
final pressure of the gas is _______atm.
a) 1.5
b) 7.5
c) 0.67
d) 3.3
e) 15
7). Give the total number of electron domains, the number of bonding domains, and the number of
lone pairs on Cl (central atom) in ClO2−.
a) four electron domains; two bonded atoms and 2 lone pairs
b) two electron domains, two bonded atoms and 2 lone pairs
c) two electron domains, two bonded atoms and 1 lone pairs
d) four electron domains; one bonded atom and 3 lone pairs
e) four electron domains, two bonded atoms, and 4 lone pairs
8) Consider four identical 1.00 L flasks containing the following gases each at 0°C and 1 atm
pressure: H2, O2, NH3, SO2. Which sample contains the most molecules?
a) SO2
b) H2
c) NH3
d) O2
e) same for all gases
9) The total number of moles of OH−ions in a mixture of 25.0 mL 0.300 M NaOH and 50.0 mL
0.200 M Ba(OH)2 is ____________. (Assume both substances completely ionize in water
solution.)
b) 7.53×1021
c) 0.0125
d) 0.0275
e) 0.0225
a) 1.36×1022
Exam 2, Form A
1
10) A sample of gas is in a closed container of constant volume and at constant temperature. You may
add 0.100 mol of any of the following gases: NH3, H2, CO2, or N2.
a) The pressure increases least for the addition of 0.100 mol H2.
b) The pressure increases more for the addition of 0.100 mol CO2 than for the addition of the same
amount of N2.
c) The increase in pressure will be proportional to the moles of gas added.
d) The increase in pressure will be proportional to the molar mass of the gas added.
e) The pressure will not increase as the conditions of the system are constant.
11) Each of three 1.0- L flasks contains 1 mole of gas at 298 K and 1 atm.
Flask 1 contains CO2
Flask 2 contains Ne
Flask 3 contains Cl2
Under these conditions,
a) the CO2 molecules have the greatest kinetic energy but the least velocity
b) the Ne atoms have the greatest kinetic energy but all of the molecules have the same
velocity
c) all of the gases have the same kinetic energy and the same velocity because the
temperature is the same
d) all of the gases have the same kinetic energy; Cl2 has the greatest velocity
e) all of the gases have the same kinetic energy; Ne has the greatest velocity
Work out the following problems and record your answers on the cover sheet. Hand in cover sheet.
1) An unknown acid reacts with NaOH according to the equation,
H2X(s) + 2 NaOH(aq) → 2 H2O(l) + Na2X(aq).
What is the molar mass of the acid if 22.4 mL of 0.0848 M NaOH is needed to neutralize 0.1846 g of
the acid?
2) Calculate the maximum heat evolved when 4.61 grams C2H5OH (46.0684 g/mol) and 9.24 g O2
(31.998 g/mol) are used in the reaction,
C2H5OH(l) + 3 O2(g) → 2 CO2(g) + 3 H2O(l)
∆H = −1367 kJ
3) An unknown liquid was vaporized in an experiment in order to find its molar mass. Calculate the
molar mass of this substance from the following recorded data:
Volume of the flask:
264 mL
Mass of empty flask 124.500 g
Barometric pressure
742.1 mmHg
Mass of flask + vapor of unknown 124.880 g
Room temperature
31.30°C
Exam 2, Form A
2
4) Several gases were put into the apparatus shown below. Calculate the total pressure of the gas
mixture when all of the stopcocks are opened and the gases are allowed to mix. (Assume that the
volumes of the connecting tubes are included in the given volumes.
CO2
3.00 L
1.00 atm
298 K
N2
2.00 L
2.00 atm
298 K
H2
2.00 L
1.00 atm
298 K
5) Automobile air bags use the decomposition of sodium azide as their source of gas for rapid
inflation:
2 NaN3(s) → 2 Na(s) + 3 N2(g) .
What mass of NaN3 (65.011 g/mol) is required to provide 40.0 L of N2 at 25.00°C and 763 mmHg?