practice questions- exam 2

Question 1

What is a unit of energy, but not the SI unit of Energy?

a. Joule
b. newton
c. pascal
d. watt
e. calorie

Answer 1

e. Calorie

Joule is the SI unit
Newton is a unit of force
Pascal is a unit of pressure

Question 2

Which is a unit of energy?
a. pascal
b. newton
c. joule
d. watt
e. ampere

Answer 2

c. Joule

Question 3

Chemical energy is
a. the kinetic energy resulting from violent decomposition of energetic chemicals.
b. the heat energy associated with combustion reactions.
c. the electrical energy produced by fuel cells.
d. the potential energy which resides in chemical bonds.
e. the energy living plants receive from solar radiation.

Answer 3

d. the potential energy which resides in chemical bonds.

Question 4

Which statement is true?
a. Molecules in gases possess kinetic energy since they are in constant motion while molecules in liquids and solids are not in constant motion and hence possess no
kinetic energy.

b. Molecules in gases and liquids possess kinetic energy since they are in constant motion, while molecules in solids are not in constant motion and hence possess no kinetic energy.

c. Molecules in gases, liquids, and solids possess kinetic energy since they are in constant motion.

d. Polyatomic molecules possess kinetic energy in the liquid and gaseous states since the atoms can move about in the molecule even if the molecule cannot move.

e. Since solids are rigid, their molecules do not possess kinetic energy unless the solid is melted.

Answer 4

c. Molecules in gases, liquids, and solids possess kinetic energy since they are in constant motion.

Question 5

A freshly baked pie is placed near an open window to cool. Which of the following statements best describes this situation?

a. The pie is the system and loses heat to the surroundings.
b. The pie is the system and gains heat from the surroundings.
c. The pie is the surroundings and gains heat from the system.
d. The pie is the surroundings and loses and gains heat to the system.
e. a and b, but not d.

Answer 5

a. The pie is the system and loses heat to the surroundings.

Question 6

A 500.0-gram sample of aluminum is initially at 25.0 °C. It absorbs 32.60 kJ of heat from its surroundings. What is its final temperature, in °C? (specific heat = 0.9930 J g 1 °C-1 for aluminum)

a. 40.4 °C
b. 64.7 °C
c. 25.1 °C
d. 89.7 °C
e. 90.7 °C

Answer 6

e. 90.7 °C

q=mc(delta)T

Question 7

A 350-gram sample of copper is initially at 77.0 °F. It absorbs 12.50 kJ of heat from its surroundings. What is its final temperature, to the nearest tenth of a degree?
(specific heat = 0.387 J g 1 °C-1 for copper)

a. 38.8 °C
b. 67.2 °C
c. 92.2 °C
d. 117.3 °C
e. 156.7 °C

Answer 7

d. 117.3 °C

q=mc(delta)T

C= (F - 32)/ (1.8)

Question 8

During an exothermic chemical reaction,

a. a system becomes warmer, and the chemical substances undergo an increase in potential energy

b. a system becomes warmer, and the chemical substances undergo a decrease in potential energy

c. a system becomes cooler, and the chemical substances undergo an increase in potential energy

d. a system becomes cooler, and the chemical substances undergo a decrease in potential energy

e. a system becomes warmer, and additional heat is gained from the surroundings

Answer 8

b. a system becomes warmer, and the chemical substances undergo a decrease in potential energy

• key word is during. think of an exothermic graph

Question 9

A bomb calorimeter consists of metal parts with a heat capacity of 950.0 J °C-1 and 8.50 × 102 grams of oil with a specific heat of 2.418 J g 1 °C-1. Calculate the amount of heat energy required, in kJ, to raise its tem¬perature from 25.00 °C to 31.60 °C.

a. 4.91 kJ
b. 11.9 kJ
c. 19.8 kJ
d. 20.8 kJ
e. 28.7 kJ

Answer 9

c. 19.8 kJ

q= qbomb + qsys

Question 10

When pure sulfuric acid is dissolved in water, heat is evolved. In a laboratory experiment to measure the molar heat of a solution of sulfuric acid, the following procedure was followed. To a calorimeter containing 3.00 × 102 g of water at 20.00 °C, 10.65 g of H2SO4, also at 20.00 °C was added. The tempera¬ture change, which was monitored by a digital thermometer with negligible heat capacity, ceased when it reached a temperature of 26.55 °C. If the specific heat of the mixture is 4.184 J g 1 °C 1, and the small heat capacity of the calorimeter is ignored, what is the heat evolved, per mole of sulfuric acid?

a. 27.4 kJ
b. 72.8 kJ
c. 78.4 kJ
d. 75.6 kJ
e. 292 kJ

Answer 10

c. 78.4 kJ

• add masses together

Question 11

An endothermic reaction is one in which there is

a. a positive value for the work done by the system (w > 0 joules)

b. a negative value for the work done by the system (w < 0 joules)

c. a negative value for ΔH (ΔH < 0 joules)

d. a positive value for ΔH (ΔH > 0 joules)

e. a negative value for ΔE (ΔE > 0 joules)

Answer 11

d. a positive value for ΔH (ΔH > 0 joules)

Question 12

In the course of measuring fuel content values, a reaction for the conversion of crude oil fuel into water and carbon dioxide is carried out in two steps
Crude fuel oil + oxygen → CO(g) + H2O
CO(g) + oxygen → CO2(g)
The net reaction taking place is simply, crude fuel oil + oxygen → CO2(g) + H2O. Actually, a large frac¬tion of the raw material is converted in one step, and the second step is just to catch the fraction that was just partially burned the first time. Anyway, for the overall or net process, which statement below is definitely always true?

a. ΔH is independent of the time interval between the two steps, but dependent on the frac¬tion which had to be converted in two steps.

b. ΔH is dependent on the time interval between the two steps, but dependent on the fraction which had to be converted in two steps.

c. ΔH is independent of the time interval between the two steps, and also independent of the fraction which had to be converted in two steps.

d. ΔH is dependent on the time interval between the two steps, but independent of the frac¬tion which had to be converted in two steps.

e. ΔH is independent of the time interval between the two steps but dependent on the time required for the completion of the entire process.

Answer 12

c. ΔH is independent of the time interval between the two steps, and also independent of the fraction which had to be converted in two steps.

Question 13

Given the reaction, 3A + 4B → 4C + 7D, and some standard enthalpies of formation:
A: +15.7 kJ mol-1 B: 86.4 kJ mol-1 C: 52.7 kJ mol-1 D: 71.6 kJ mol-1

What is the standard enthalpy of reaction, in kJ for the reaction shown?

a. -53.6 kJ
b. -413.5 kJ
c. -515.6 kJ
d. -853.6 kJ
e. -908.4 kJ

Answer 13

b. 413.5 kJ

(delta)H= H[products] - H[reactants]

Question 14

The thermochemical equation which is associated with, the standard enthalpy of formation, for HCl(g), is

a. H(g) + Cl(g) → HCl(g)
b. H2(g) + Cl2(g) → 2 HCl(g)
c. ½ H2(g) + ½ Cl2(g) → HCl(g)
d. H2(g) + Cl2(l) → 2 HCl(g)
e. ½ H2(g) + ½ Cl2(l) → HCl(g)

Answer 14

c. ½ H2(g) + ½ Cl2(g) → HCl(g)

(delta)H-formation 1 mole of molecule

Question 15

The thermochemical equation which is associated with, the standard enthalpy of formation, for glucose, C6H12O6(s), is

a. 6 C(s) + 6 H2O(l) → C6H12O6(s)
b. 6 C(s) + 12 H(g) + 6 O(g) → C6H12O6(s)
c. 6 C(s) + 6 H2(g) + 3 O2(g) → C6H12O6(s)
d. 2 C2H5OH(l) + 2 CO2(g) → C6H12O6(s)
e. 6 C(g) + 6 H2(g) + 3 O2(g) → C6H12O6(s)

Answer 15

c. 6 C(s) + 6 H2(g) + 3 O2(g) → C6H12O6(s)

carbon is a solid

Question 16

The thermochemical equation which is associated with, the standard enthalpy of formation, for urea, CO(NH2)2(s), is

a. CO(g) + 2 NH3(g) → CO(NH2)2(s) + H2(g)

b. CO(g) + 2 H2(g) + N2(g) → CO(NH2)2(s)

c. C(s) + O(g) + N2(g) + 2 H2(g) → CO(NH2)2(s)

d. C(s) + ½ O2(g) + N2(g) + 2 H2(g) → CO(NH2)2(s)

e. C(s) + ½ O2(g) + 2 NH2(g) → CO(NH2) 2(s)

Answer 16

d. C(s) + ½ O2(g) + N2(g) + 2 H2(g) → CO(NH2)2(s)

Question 17

0.600 L of 240 mM perchloric acid, HClO4(aq) was added to a high-quality constant-pressure calorime¬ter containing 0.400.0 L of 0.300 M KOH(aq). Both solutions have a density of 1.000 kg L-1 and a specific heat of 4.184 J g 1 °C-1. The calorimeter had a heat capacity of 950.0 J °C-1. The temperature of the entire system rose from 25.30 °C to 79.86°F. Calculate the heat of the reaction, in kJ, per mole of KOH(aq)

a. 54.76
b. 57.19
c. 51.19
d. 58.91
e. 59.19

Answer 17

a. 54.76

q= qbomb + qsys
* use liters to find grams
*divide energy by moles gotten from molarity

Question 18

The increase in atomic radius as one progresses within the alkali metal family from element Z = 3 to Z = 87 in the periodic table can be attributed to

a. the increase in the principal quantum number of the outermost occupied orbital in the atom

b. the decrease in the principal quantum number of the outermost occupied orbital in the atom

c. the increase in the effective nuclear charge being experienced by the electron(s) in the outermost occupied orbital in the atom

d. the decrease in the effective nuclear charge being experienced by the electron(s) in the outermost occupied orbital in the atom

Answer 18

a. the increase in the principal quantum number of the outermost occupied orbital in the atom

Question 19

Bromine tends to form simple ions which have the electronic configuration of a noble gas. What is the electron configuration of that noble gas?

a. 1s2 2s2 2p6 3s2 3p6 3d10 4p6
b. 1s2 2s2 2p6 3s2 3p6 4p6 4d10
c. 1s2 2s2 2p6 3s2 3p6 4s2 4p6
d. 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6
e. 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10

Answer 19

d. 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6

Question 20

Which bond is the most polar?

a.	H—C
b.	H—Cl
c.	H—P
d.	H—S
e.	H—Se

Answer 20

b. H—Cl

Question 21

The wavelength of an electromagnetic wave is

a. the number of complete oscillations or cycles over a distance of one meter.

b. the number of complete oscillations or cycles in a one second time interval.

c. the distance between successive maxima in the wave.

d. the number of complete oscillations or cycles over a distance of one centimeter.

e. the distance between a minimum and the nearest maximum in the oscillation

Answer 21

c. the distance between successive maxima in the wave.

Question 22

Which statement is true?

a. The line spectra of atoms consist of a series of white lines superimposed on a colored background.

b. The line spectra of atoms consist of a series of white lines superimposed on a dark background.

c. The line spectra of atoms consist of a series of colored lines superimposed on a dark background.

d. The line spectra of atoms consist of a series of dark lines superimposed on a white background.

e. The line spectra of atoms consist of a series of dark lines superimposed on a colored background.

Answer 22

c. The line spectra of atoms consist of a series of colored lines superimposed on a dark background.

Question 23

Which statement is true concerning Bohr’s model of the atom?

a. The model accounted for the absorption spectra of atoms but not for the emission spectra.
b. The model could account for the emission spectrum of hydrogen and for the Rydberg equation.
c. The model was based on the wave properties of the electron.
d. The model accounted for the emission spectra of atoms, but not for the absorption spectra.
e. The model was generally successful for all atoms to which it was applied.

Answer 23

b. The model could account for the emission spectrum of hydrogen and for the Rydberg equation.

Question 24

The definite energies associated with specific wavelengths in the emission spectrum of atomic hydro-gen suggest that

a. electrons have a smaller rest mass than photons

b. photons have a smaller rest mass than electrons

c. energy states in the hydrogen atom are quantized

d. atomic hydrogen is more stable and has a lower potential energy than molecular hydrogen

e. the potential energy of electrons in the atom can have any arbitrary value over a period of time, but the kinetic energy may only have certain specific values.

Answer 24

c. energy states in the hydrogen atom are quantized

Question 25

14. The visible region lines for the hydrogen spectrum when n = 2 in the Rydberg equation constitute the Balmer series. What is the wavelength of the light discharged, of the spectral line in the series for which n2 = 4?

a. 485.3 mm
b. 4.853 nm
c. 4.85 x 10-6 cm
d. 4.85 x 10-7 m
e. 485.3 km

Answer 25

d. 4.85 x 10-7 m

Question 26

18. A sodium lamp glows yellow: identical to a sodium atom’s line emission spectra. Which statement best describes this observation?

a. The wavelength of the light emitted is equivalent to the red light emitted by burning chromium.

b. The wavelength of the light emitted is equivalent to the energy emitted by the drop in shells by the electrons.

c. The wavelength of the light emitted is equivalent to the energy gained by the drop in energy shells by the electrons.

d. The wavelength of the light absorbed is equivalent to the energy gained by the drop in energy shells by the electrons.

e. The wavelength of the light absorbed is equivalent to the energy lost due to the drop in energy shells by the electrons.

Answer 26

b. The wavelength of the light emitted is equivalent to the energy emitted by the drop in shells by the electrons.

Question 27

Periodic trends: atomic radius, I.E, E.A, electronegativity,

Answer 27

atomic radius: increase right to left, increases going down
IE: increases left to right, increases going up
E.A: increases left to right, increases going up
electronegativity: increases left to right, increases going up