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Lesson: Prevention of Rusting

Worksheet • 20 Questions

Q1:

An electrochemical cell is constructed by connecting plates of iron and copper to a voltmeter and immersing the plates in separate salt solutions linked via a salt bridge. Ferroxyl indicator is added to each of the two solutions. Which of the following images best illustrates the colors of the solutions at the end of this experiment? Note that the salt bridges are omitted for clarity.

  • A
    V F erroxyl Indicator F e C u
  • B
    V F erroxyl Indicator F e C u
  • C
    V F erroxyl Indicator F e C u
  • D
    V F erroxyl Indicator F e C u
  • E
    V F erroxyl Indicator F e C u

Q2:

A steel vehicle is protected from rusting by spraying the exposed surface with a second metal.

What name is given to this process?

  • AGalvanization
  • BAlloying
  • CElectroplating
  • DPassivation
  • EPainting

What name is given to the protective metal layer?

  • ASacrificial anode
  • BElectrical insulation
  • CSacrificial cathode
  • DAlloy
  • EPassivating layer

Q3:

A steel can is protected by coating it with a layer of tin. Part of the steel surface is exposed through a scratch in the tin layer, as shown. How does the rate of rusting of the steel exposed by the scratch compare with that of uncoated steel?

  • AThe exposed steel rusts more rapidly than uncoated steel.
  • BIron in the steel reacts with tin to form a new protective layer, so no steel is exposed.
  • CThe exposed steel rusts but more slowly than uncoated steel.
  • DThe exposed steel does not rust, unlike uncoated steel.
  • EThe exposed steel rusts at the same rate as uncoated steel.

Q4:

Vehicle components are sometimes made of aluminum instead of steel in order to reduce the risk of oxidation.

Why is aluminum less susceptible than steel to oxidation?

  • AAluminum is protected by an unreactive oxide layer.
  • BAluminum forms cracks less easily than steel.
  • CAluminum is less reactive than steel.
  • DAluminum is protected by an unreactive carbonate layer.
  • EAluminum binds water less strongly than steel.

Which of the following is another advantage of using aluminum instead of steel in vehicle components?

  • AAluminum is less dense than steel.
  • BAluminum is less expensive than steel.
  • CAluminum is stronger than steel so it deforms less easily.
  • DAluminum has a higher melting point than steel.
  • EAluminum is harder than steel so it scratches less easily.

Q5:

An iron surface is protected from rusting by coating it with a sacrificial metal from a salt solution. Which process is responsible for the formation of the protective layer?

  • AReduction of dissolved metal ions by an electric current
  • BReaction of dissolved metal ions with atmospheric oxygen
  • CReaction of dissolved metal ions with the iron surface
  • DReaction of dissolved metal ions with surface iron oxides
  • EOxidation of dissolved metal ions by an electric current

Q6:

The diagram illustrates an iron plate that has been protected from rusting by galvanization of the exposed surface.

Identify the material usually present in the protective coating X .

  • AZinc
  • BOil
  • CTin
  • DPlastic
  • ECopper

When intact, how does the coating protect the iron plate?

  • AThe coating physically prevents oxygen and water from reaching the iron plate.
  • BThe coating traps rust to prevent it from flaking away.
  • CThe coating reacts with oxygen to prevent it from reaching the iron plate.
  • DThe coating binds water to prevent it from reaching the iron plate.
  • EThe coating reacts with rust to convert it back to metallic iron.

If the coating is scratched, how does it continue to protect the iron plate?

  • AThe coating is oxidized instead of the iron plate.
  • BThe coating cannot protect the iron plate if scratched.
  • CThe coating flows to fill the scratch.
  • DThe coating reacts with the exposed iron to form a rust-resistant alloy.
  • EThe coating absorbs water and expands to fill the scratch.

Q7:

Which of the following is the best definition of passivation?

  • AProtection of a metal surface by an unreactive oxide layer
  • BProtection of a metal surface by an unreactive oil layer
  • CProtection of a metal surface by a sacrificial material
  • DProtection of a metal surface by an electrical current
  • EProtection of a metal surface by an unreactive plastic layer

Q8:

The Statue of Liberty in New York City contains a copper skin wrapped around iron supports. Why is this design problematic?

  • ACopper is less reactive than iron, so it accelerates rusting of the iron support.
  • BCopper binds water more strongly than iron, so it accelerates rusting of the iron support.
  • CCopper cannot form an alloy with iron, so the iron support is exposed to rusting.
  • DCopper has a low tensile strength so it cracks easily, exposing the iron support to rusting.
  • ECopper develops a thick oxide layer, preventing it from acting as a sacrificial coating for the iron support.

Q9:

Iron may be protected from rusting by supplying the metal with an electric current. Why does this method lower the risk of rusting?

  • AThe supply of electrons converts iron ions back to metallic iron.
  • BThe supply of electrons causes the iron surface to become charged, binding oxygen molecules less strongly.
  • CThe supply of electrons converts oxygen to water, preventing it from acting as an oxidant.
  • DThe supply of electrons causes the iron surface to become charged, binding protective surface oxides more strongly.
  • EThe supply of electrons promotes the formation of a protective surface oxide layer.

Q10:

Which of the following is the best definition of galvanic corrosion?

  • AOxidation of a metal accelerated by the presence of a less reactive metal
  • BReduction of a metal accelerated by alloying
  • COxidation of a metal accelerated by the presence of a more reactive metal
  • DReduction of a metal accelerated by the presence of a less reactive metal
  • EOxidation of a metal accelerated by alloying

Q11:

Which of the following is not a method for lowering the rate of rusting?

  • AWelding
  • BGalvanization
  • CAlloying
  • DElectroplating
  • EGreasing

Q12:

Which of the following is not a useful property in protective oil coatings for moving steel components?

  • AHigh viscosity
  • BLow melting point
  • CLow volatility
  • DHigh hydrophobicity
  • ELow reactivity

Q13:

A steel oil pipeline is protected via an electrical connection to a buried block of sacrificial metal. Which diagram correctly illustrates the composition of the sacrificial metal and the direction of the electrical current?

  • A
  • B
  • C
  • D
  • E

Q14:

What is the main reason for preferring oil over plastic as a protective coating for a steel bicycle chain?

  • AOil can spread to maintain a uniform coating during movement of the chain.
  • BOil is less heavy than plastic so is less likely to impede the chain movement.
  • CThe oil layer reduces oxidation by acting as a sacrificial coating.
  • DOil is less likely to react with the steel chain.
  • EOil is less expensive than a plastic coating.

Q15:

Which of the following is not a useful property in protective plastic coatings for moving steel components?

  • ALow melting point
  • BHigh hydrophobicity
  • CLow weight
  • DHigh yield point
  • EHigh elasticity

Q16:

Which of the following metals could be used as a sacrificial coating on iron to prevent rust formation?

  • A A l
  • B P t
  • C S n
  • D C u
  • E P b

Q17:

Based on their positions on the reactivity series, and their densities, which of the following metals would produce the lightest sacrificial coating for a lead object?

  • AZinc
  • BIron
  • CNickel
  • DTin
  • ECopper

Q18:

Which of the following could not be used as a sacrificial metal to prevent corrosion of tin?

  • ALead
  • BIron
  • CMagnesium
  • DZinc
  • EAluminum

Q19:

Which term best describes the protective material used in cathodic protection?

  • ASacrificial anode
  • BHydrophobic layer
  • CSacrificial cathode
  • DAlloy
  • EPassivating layer

Q20:

Which of the following is not a useful property in sacrificial metal coatings for steel objects?

  • ALow reactivity
  • BHigh melting point
  • CHigh hydrophobicity
  • DLow density
  • EHigh tensile strength
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