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Practice Final Exam Flashcards

1
Q

What is the coefficient for oxygen in the properly balanced equation for the combustion of propanol in oxygen gas to form carbon dioxide gas and water according to the equation:

C3H8O + O2 -> CO2 + H2O

A

9

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2
Q

Ammonia (NH3) is produced industrially using the Haber-Bosch process (1912) which combines nitrogen (N2) and hydrogen (H2) at high temperatures (500°C) and high pressures (200 atm). What is the theoretical yield of ammonia (NH3) that can be produced when a cylinder containing 50.0 kg of nitrogen gas (N2) is reacted with excess hydrogen gas (H2)?

A

60.8 kilograms (3570 moles)

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3
Q

Which of the following represents the net ionic equation of the combination of insoluble of aluminum hydroxide and a solution of hydrobromic acid?

A

Al(OH)3(s) + 3H+ -> Al3+(aq) + 3H2O(l)

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4
Q

30.0 mL of a sulfuric acid solution of unknown molarity is titrated against 27.3 mL of a standardized 0.55 M sodium hydroxide solution. What is the concentration of the sulfuric acid solution? Recall that sulfuric acid is a diprotic acid.

A

0.25 M H2SO4

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5
Q

A balloon containing 4.28 L of an unknown gas at 1.00 atm and 298 K has a mass of 16.90 g. The empty balloon has a mass of 2.24 g. What is the molar mass of the gas in the balloon?

A

83.8 g/mol

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6
Q

Calculate the average speed (root-mean-square speed) of a gas that has a molar mass of 1.73 × 10−2 kg / mol at a temperature of 39°C. The value for the gas constant, R, is 8.314 J / mol K. Also, remember that 1 J = 1 kg m2/s2, so 1 J / kg = 1 m2/s2.

A

671 m / s

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7
Q

In the field of thermodynamics, what are the surroundings?

A

everything other than the system

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8
Q

A coffee cup (or constant pressure) calorimeter contains 108.0 g of water at an initial temperature of 25.0°C. 118.7 g of tin metal at a temperature of 100°C is added. The final temperature in the calorimeter is 29.2°C. What is the molar heat capacity of the tin? The molar heat capacity of water is 75.4 J / (mol•°C). Assume that the heat capacity of the coffee cup is negligible.

A

26.8 J / (mol•°C)

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9
Q

Only the number of valence electrons has an influence on the chemical properties of an element.

A

false

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10
Q

As you move from the left to the right across the periodic table, which of the following is the trend?

A

Increasing ionization energy

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11
Q

Which of the following compounds is not expected to form:

A

NaCO3

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12
Q

The electron configuration of argon is 1s22s22p63s23p6.

How many valence electrons does argon have?

A

8

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13
Q

Which of the following is the correct Lewis dot structure of the ethoxide anion, [CH3CH2O]−?

A

-

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14
Q

What are the oxidation numbers for magnesium and oxygen (in that order) in the MgO molecule?

A

+2, −2

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15
Q

For London dispersion forces to be present, the molecule must have a permanent dipole moment.

A

false

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16
Q

When making home-made ice cream, table salt, sodium chloride, is mixed with ice to lower the temperature. Suppose 500 grams of salt are mixed with 8.0 liters of water to make a solution. What is the freezing point of this solution?

A

−3.98°C

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17
Q

Ink is composed of a solid dispersed in a liquid. Therefore, ink is a(n) _____.

A

sol

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18
Q

Using the following data for the reaction 2NO2(g) + F2(g) → 2FNO2(g), what are the values of m, n, and k in the rate law rate = k[ NO2 ]m [ F2 ]n?

A

m = 1, n = 1, k = 24 M −1 • s−1

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19
Q

The accepted mechanism for the reaction of methane (CH4) and chlorine (Cl2) to produce chloromethane (CH3Cl) is:

Based on this mechanism, what is the rate law for this reaction?

A

rate = k[Cl2]

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20
Q

What is the percent dissociation of a 0.20 M solution of the weak base methylamine? (NH2CH3 )?
(Kb = 4.4 × 10−4 )

A

4.7

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21
Q 
Reaction A (overall reaction):
HCOOH(aq) + NaOH(aq) <==> Na(HCOO)(aq) + H2O(l)

Reaction B:
HCOOH(aq) + H2O(l) <==> H3O+(aq) + HCOO-(aq)

Reaction C:
H3O+(aq) + OH-(aq) <==> 2H2O(l)

Reaction D:
HCOOH(aq) + OH-(aq) <==> H2O(l) + HCOO-(aq)

For equations B and C,
Ka = 1.8*10^-4 and Kw = 1 * 10^-14

Which statement about the intermediate reactions and this overall reaction is completely correct?

A

Reaction C is the reverse reaction of the autoionization of water. Koverall = Ka(1 / Kw ).

22
Q

You add 0.01 moles of normally insoluble silver chloride (AgCl) to 1 L of 0.800 ammonia (NH3). The following reaction occurs:
Ag+(aq) + 2NH3(aq) <==> Ag(NH3)+(aq)
Kf = 1.7*10^7

What is the equilibrium concentration of silver ion (Ag+)?

A

9.2 x 10^–10

23
Q

The greater the difference in electronegativity between two atoms, the more polarized the bond, and the more likely the bond will break heterolytically.

A

true

24
Q

Given the following reaction:

CH3NH2(aq) + H2O(l) <==> Ch3NH3+(aq) + OH-(aq)

Which species is the conjugate acid of methylamine?

A

CH3NH3+

25
Q

A Brønsted-Lowry acid is a molecule that can donate an electron pair.

A

false

26
Q

Which of the following statements about the leaving group is TRUE?

A

The weaker the base, the better it is as a leaving group

27
Q

Which of the following defines the entropy change (ΔS) for a system at equilibrium?

A

ΔS = q/T

28
Q

The reaction between hydrogen gas and oxygen gas to produce water is very exothermic, and equilibrium lies very far to the right. Which of the following describes ΔG for this reaction at equilibrium?

A

ΔG = 0 kJ/mol

29
Q

Which of the following is the properly balanced equation for the net ionic equation below in acidic solution?
MnO4-(aq) + CN-(aq) -> MnO2(aq) + OCN-(aq)

A

2H+(aq) + 2MnO4-(aq) + 3CN-(aq) -> 2MnO2(aq) + H2O(l) + 3OCN-(aq)

30
Q

Galvanized iron is iron with a layer of zinc coated on it. How does the galvanization protect the iron from corrosion?

A

Zinc primarily acts as a sacrificial anode, but is also capable of acting as a passivation agent.

31
Q

A semiconductor is able to conduct a current:

A

in both the conduction band and the valence band.

32
Q

How are the alkali metals generally isolated?

A

Reduction of the chloride salt by chemical or electrical means

33
Q

Which of the following is not a part of DNA?

A

Ribose

34
Q

Look at the two propanol molecules.

Which statement about these molecules is not correct?

A

In alcohol molecules with three or fewer carbons, the location of the OH group must be specified

35
Q

Which of these is an example of a solution?

A

pure air

36
Q

Which of these waves has the greatest amplitude?

A

-

37
Q

Which if the following is not a component of an s orbital?

A

angular nodes

38
Q

The bond length of a single bond is ___________ the bond length of a double bond.

A

greater than

39
Q

Which statement about valence bond theory is not true?

A

An atom with a filled valence shell is unstable and therefore very willing to form a covalent bond with another atom.

40
Q

Use the diagram for the predicted bonding orbitals in hydrogen fluoride, HF, and decide which of the following statements is not correct.

Assume the molecule is oriented along the z axis.

A

The degenerate pair of molecular orbitals are the fluorine 2px and 2pz.

41
Q

The Henry’s Law constant of nitrogen at 25°C in water is 8.57 × 104 atm. Calculate the number of moles of nitrogen that dissolve per kg of water for nitrogen at 2.0 atm.

Pgas = kHXgas

A

1.3 × 10^−3 mol

42
Q

Which statement about the reaction shown below is not correct?

CH4(g) + H2O(g) <==> CO(g) + 3H2(g)
(where Kp = 1.8*10^-7 (at 600K))

A

If you start with a system that is not at equilibrium and has no H2, adding more CH4 and H2O will avoid the formation of H2 at equilibrium.

43
Q

Suppose that you have a 43 mL solution of 0.23 M HCl that is being titrated with 0.17 M NaOH. You stop the titration after adding 27 mL of NaOH. What is the change in pH at this point?

A

0.48

44
Q

Which statement about a diprotic acid is not true?

A

A diprotic acid has at least two protons available whose Ka values are equal

45
Q

244 88 Ra -> 244 88 Ra + γ

Which of the following statements about this event is not correct?

A

In a gamma radiation emission, the parent element is different from the daughter element.

46
Q

You have a sample of bone collected from Nevada and you find that it contains strontium-90 and exhibits an activity of 2.5 Bq. How much strontium-90 was present in the bone when the animal died 45 years ago? (The half-life of 90Sr is 29 years.)

A

9.7 x 10^9

47
Q

Which statement about fission reactions is not true?

A

A fission reaction can produce a limited amount of CO2, which adds to the greenhouse effect

48
Q

All of the following are classes of binary hydrides except:

A

covalent hydrides

49
Q

How does treatment with carbon make metals (such as tungsten and iron) change their composition?

A

The carbon is able to collect in the intersticies of the metal lattice and provide a much more stable structure

50
Q

Which technique is used most often commercially in preparation of halogens?

A

electrolysis

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