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Quiz Session - Attempts With Random Questions

College Chemistry Exam Questions

Page 7 of 25

121.

It is easy to mix up the names of similar compounds. What are the names, in order, of the following nitrogen-containing ions:

NH4+, NO3-, NO2-, N3- 

  • Ammonium, nitrate, nitrite, nitride

  • Ammonium, nitride, nitrite, nitrate

  • Ammonium, nitride, nitrate, nitrite

  • Nitride, ammonium, nitrite, nitrate

  • Nitride, ammonium, nitrate, nitrite

Correct answer: Ammonium, nitrate, nitrite, nitride

Many sets of similar negative ions contain an -ate, -ite, and -ide. As a general rule, the largest ion ends in -ate, followed by -ite, followed by -ide. For example, SO42- = sulfate, SO32- = sulfite, and S2- = sulfide.

122.

Rank the following functional groups in terms of increasing bond order (from lowest to highest):

Alkane, Alkene, Alkyne

  • Alkane < Alkene < Alkyne

  • Alkane < Alkyne < Alkene

  • Alkyne < Alkane < Alkene

  • Alkene < Alkane = Alkyne

  • Alkyne < Alkene = Alkyne

Correct answer: Alkane < Alkene < Alkyne 

These are all carbon-containing compounds. An Alkane contains only single C-C bonds, while an Alkene is a double bond and an Alkyne is a triple bond.

123.

What does the van der Waals Equation do?

  • Correct for non-ideal properties of real gases

  • Quantify the effect of a solute on a solution's vapor pressure

  • Estimate osmotic pressure

  • Apply the Ideal Gas Law to the special case of noble gases

  • Explain several anomalous properties of water

Correct answer: Correct for non-ideal properties of real gases

The van der Waals Equation modifies PV=nRT to address two realities: gas molecules do occupy some space and do interact with each other. Though it is more accurate than PV=nRT, the adjusted equation is quite cumbersome to use, so for many purposes, PV=nRT is adequate.

124.

You want to remove an electron from an alkali metal using the least amount of energy possible. How should you choose which metal?

  • The alkali metal with the largest radius

  • The alkali metal with the lowest density

  • The alkali metal with the highest ionization energy

  • The alkali metal with the highest melting point

  • The alkali metal with the fewest protons

Correct answer: The alkali metal with the largest radius

The larger the radius, the more loosely held the valence electrons. Francium (the last alkali metal in the column) is, therefore, the easiest to ionize, while lithium is the most difficult (though still quite easy). All other trends lists actually point to the element requiring more, not less, energy to ionize.

125.

Osmosis is the diffusion of water through:

  • A semipermeable membrane

  • A permeable membrane

  • A capillary

  • A flexible opening

  • A channel

Correct answer: A semipermeable membrane

Osmosis occurs when water and solute appear on two sides of a semipermeable membrane. The membrane allows water to pass, but the solute cannot. Water, therefore, flows across the membrane in one direction or the other until there is equal solute concentration on both sides.

126.

Hydroxide (OH-) is generally insoluble unless paired with:

i. Pb2+

ii. Ba2+

iii. Sr2+

iv. Group I elements

v. Group II elements

  • ii., iii., and iv.

  • ii. and v.

  • i. and iii.

  • i., ii., and iv.

  • ii., iii., and v.

Correct answer: ii., iii., and iv.

It is useful to memorize these exceptions to general solubility rules. In addition, Ca(OH)2 is slightly soluble.

127.

When iron rusts or an apple browns, a reaction is occurring as a result of exposure to oxygen in the air. What are the roles of oxygen in this reaction?

  • Oxygen gets reduced but acts as an oxidizing agent

  • Oxygen gets oxidized but acts as a reducing agent

  • Oxygen gets reduced and acts as an acid

  • Oxygen gets oxidized and acts as a base

  • Impossible to say without knowing the other reactants

Correct answer: Oxygen gets reduced but acts as an oxidizing agent

This is a classic redox reaction: oxygen gas and another molecule both have oxidation states of 0 initially. Oxygen gains electrons from the other molecule (a metal or otherwise) and therefore gets reduced. Because oxygen removes electrons from another atom, oxygen is considered an oxidizing agent. This is not an acid-base reaction because it does not involve any transfer of protons.

128.

Consider this equation: Al + O2 -->  Al2O3

Which version is balanced appropriately?

  • 4Al + 3O2 -->  2Al2O3

  • Al + O2 -->  Al2O3

  • 2Al + 1.5O2 -->  Al2O3

  • 2Al + O2 -->  Al2O3

  • 8Al + 6O2 -->  4Al2O3

Correct answer: 4Al + 3O2 -->  2Al2O3

This uses the simplest possible whole number coefficients. When balancing equations, make sure that you have the same number of each element on both sides (in this case, 4 Al and 6 O) and that you have simplified the ratio of coefficients.

129.

What is the first step in balancing net ionic equations?

  • Write the half-reactions

  • Balance all atoms except for C, H, and O

  • Balance all atoms except for O and H

  • Balance O and H by adding H2O and H+ as needed

  • Add electrons to one side or the other to balance charge

Correct answer: Write the half-reactions

It is best to work with net ionic equations by considering their component parts: oxidation and reduction. Once you balance atoms and charge within the half-reactions, you can add the equations together for the final product.

130.

The following reaction is sometimes referred to as a "double displacement" reaction:

CaCl2 (aq) + 2 AgNO3 (aq) → Ca(NO3)2 (aq) + 2 AgCl (s)

What other type of reaction is it?

  • Precipitation

  • Redox

  • Synthesis

  • Single replacement

  • Neutralization

Correct answer: Precipitation

In this case, four soluble ions recombine in a way that creates an insoluble product, or precipitate. It is not, however, a redox reaction because none of the atoms change oxidation states.

131.

You have a mixture of uranium isotopes with mass 235 (U-235) and 238 (U-238), and you run the mixture through mass spectrometry. How will you tell the isotopes apart?

  • U-235 will be deflected further than U-238 on the photographic plate

  • U-238 will be deflected further than U-235 on the photographic plate

  • U-238 will arrive before U-235 at the photographic plate

  • U-235 will arrive before U-238 at the photographic plate

  • You won't be able to tell them apart because they still have the same charge

Correct answer: U-235 will be deflected further than U-238 on the photographic plate

In mass spectrometry, atoms with smaller mass are more affected by the magnetic field, causing their path to bend and land farther from center on the photographic plate. In contrast, atoms with larger mass are less affected by the field and travel on a straighter path. 

132.

Most names of binary compounds don't include any numbers (for example, "aluminum hydroxide," "barium oxide," etc.). So why is "iron(II) chloride" written with a number?

  • Iron has more than one possible oxidation state

  • Iron has more than one possible isotope

  • There are multiple types of the iron element

  • It is a remnant of an old nomenclature system but doesn't need to be written this way

  • It is a stylistic preference but doesn't need to be written this way

Correct answer: Iron has more than one possible oxidation state

Some metals (iron, copper, gold, tin, chromium, mercury, and lead) can form two or even three oxidation states. Since iron can form a 2+ or 3+ ion, the name "iron chloride" could indicate either FeCl2 or FeCl3. We, therefore, include the oxidation state of iron for clarification.

133.

What coefficients would balance the following equation?

__(NH4)3PO4 + __Pb(NO3)4 → __Pb3(PO4)4 + __NH4NO3

  • 4, 3, 1, 12

  • 4, 3, 1, 3

  • 1, 3, 1, 4

  • 8, 6, 1, 12

  • 1, 1, 1, 3

Correct answer: 4, 3, 1, 12

Since NH4 and NO3 consistently travel together, it is easiest to balance this equation by considering these as single units rather than accounting for N, H, and O separately.

134.

Balance the following chemical equation. What are the appropriate coefficients (in order)?

__Pb(OH)4 + __H2SO4 → __Pb(SO4)2 + __H2O

  • 1, 2, 1, 4

  • 1, 2, 1, 1

  • 1, 2, 1, 2

  • 2, 4, 2, 8

  • 1, 1, 1, 4

Correct answer: 1, 2, 1, 4

Though 2, 4, 2, 8 is technically balanced as well, chemical equations should always be written with the lowest possible coefficients (unless specified otherwise).

135.

The "alcohol" humans consume is ethyl alcohol or C2H6O. Which part of this molecule gives it the "alcohol" in its name?

  • Terminal -OH

  • Terminal -CH3

  • C-C single bond

  • C-O single bond

  • Content of two C atoms

Correct answer: Terminal -OH

An "alcohol" is an -OH group located off the carbon chain. The other part of this molecule's name, "ethyl," comes from having two C atoms.

136.

What is the net ionic equation for the following reaction?

AgNO3(aq) + KCl(aq) → AgCl(s) + KNO3(aq)

  • Ag+(aq) + Cl-(aq) → AgCl(s)

  • AgNO3(aq) + KCl(aq) → AgCl(s)

  • Ag+(aq) + NO3- (aq) + K+ (aq) + Cl-(aq) → AgCl (s) + K+ (aq) + NO3- (aq)

  • NO3- (aq) + K+ (aq) →  KNO3 (aq)

  • AgNO3 (aq) + K+ (aq) →  KNO3 (aq)

Correct answer: Ag+(aq) + Cl-(aq) → AgCl(s)

To write the net ionic equation, you can first write the total ionic equation by separating soluble ions into their constituent parts:

Ag+(aq) + NO3- (aq) + K+ (aq) + Cl-(aq) → AgCl (s) + K+ (aq) + NO3- (aq)

Then eliminate the spectator ions (those that are present on both sides of the equation, in this case K+ and NO3-).

137.

Carbon dioxide (CO2) is consumed in photosynthesis and used by plants to make glucose (C6H12O6, molecular mass 180 amu). This process involves the carbon in CO2 getting “fixed” onto a molecule within the plant, while the oxygen is ultimately released. Imagine that you have an apparatus that can measure the amount of CO2 consumed by a plant in a closed space. You record that a plant has consumed 10g CO2.

How much glucose do you think the plant has produced? Atomic masses: C = 12.01 amu, O = 16.00 amu.

  • 7.14g

  • 300g

  • 2.86g

  • 25.08g

  • 42.85g

Correct answer: 7.14g

Remember that you need to adjust the 10g CO2 to reflect the mass that is attributable to carbon only. Then, you can determine how much glucose can be produced with that amount of carbon:

(10g CO2) * (1 mol C / 42.01g CO2) * (1 mol C / 1 mol CO2) * (12.01g C / 1 mol C) * (1 mol glucose / 72.06g C) * (180g glucose / 1 mol glucose) = 7.14g glucose

138.

Assume that chlorine is neutral. It has 17 electrons and an atomic mass of 35. How many neutrons does chlorine have?

  • 18

  • 17

  • 35

  • 36

  • Impossible to say without knowing how much of the atomic mass is attributable to protons

Correct answer: 18

If chlorine is neutral, then it must have the same number of protons and electrons (17 of each). Since electrons have almost no mass, atomic mass is essentially the number of protons + neutrons. Therefore, there must be 35 – 17 = 18 neutrons.

139.

In H2O, what is the percentage of hydrogen by mass? Use approximated atomic masses: H = 1 amu, O = 16 amu.

  • 1/9

  • 1/8

  • 1/4

  • 1/18

  • 1/16

Correct answer: 1/9

The molecular mass of H2O = 1(2) + 16(1) = 18 amu. To find hydrogen's proportion of the mass, divide hydrogen's mass by the total molecular mass: 2/18 or 1/9.

140.

What forms in a reaction between a strong acid and a strong base?

  • Water

  • Acidic salt

  • Neutral salt

  • Basic salt

  • Depends on the specific acid and base

Correct answer: Water

Since both the acid and the base are "strong," they almost fully dissociate in solution. This yields H+ and OH- ions that combine to form water.

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