Nagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy.

Lesson: Rusting

Worksheet • 17 Questions

Q1:

When an iron nail rusts, it reacts with oxygen and water in the air. What happens to the total mass of the nail?

  • AIt decreases
  • BIt increases
  • CIt stays the same

Q2:

Rusting of iron is an example of an oxidation reaction. The rate of rusting of iron in water varies with increasing salt concentration.

Which particles are removed from a metal during an oxidation reaction?

  • AElectrons
  • BNeutrons
  • CProtons
  • DHydrogen atoms
  • EOxygen atoms

How and why does the rate of rusting of iron in water vary with increasing salt concentration?

  • AThe rate increases because dissolved ions aid the movement of charge.
  • BThe rate increases because dissolved ions react with the metal atoms.
  • CThe rate decreases because dissolved ions react with dissolved oxygen.
  • DThe rate increases because dissolved ions aid the decay of metal nuclei.
  • EThe rate decreases because dissolved ions aid the ionization of water.

Which term best describes the role of the salt solution in the rusting process?

  • AElectrolyte
  • BAcid
  • COxidizing agent
  • DBase
  • EReducing agent

Q3:

Give a balanced chemical formula for the formation of the major iron oxide compound in rust.

  • A 4 F e + 3 O 2 F e O 2 2 3
  • B 3 F e + 2 O F e O 2 3 4
  • C 2 F e + O 2 F e O 2
  • D F e + O F e O 2 2
  • E 3 F e + O F e O 2 3 2

Q4:

Two moles of iron react with one mole of oxygen to produce a colored compound of uniform composition. All of the iron reacts and there are no other products.

What is the formula of the compound produced?

  • A F e O
  • B F e O 2
  • C F e O 2 3
  • D F e O 3 4
  • E F e O 3 2

What color is the compound produced?

  • ABlack
  • BWhite
  • CRed
  • DYellow
  • EGreen

The compound reacts with further oxygen to form a more stable material. What color is the new material?

  • ARed
  • BWhite
  • CBlack
  • DYellow
  • EGreen

Q5:

Two sealed iron tanks, 𝐴 and 𝐡 , contain identical volumes of water at room temperature. Tank 𝐴 contains water that was boiled before being placed in the tank, while the water in tank 𝐡 was not boiled. How and why does the rate of rusting differ between the two tanks?

  • AThe rate of rusting is lower in tank 𝐴 as boiling of water reduces the amount of dissolved oxygen.
  • BThe rate of rusting is higher in tank 𝐴 as boiling of water reduces the amount of dissolved salt.
  • CThere is no difference in the rate of rusting.
  • DThe rate of rusting is lower in tank 𝐴 as boiling of water reduces the amount of dissolved salt.
  • EThe rate of rusting is higher in tank 𝐴 as boiling of water increases the amount of dissolved oxygen.

Q6:

Acid rain is produced when sulfur dioxide in the atmosphere reacts with water to form sulfuric acid. Increasing the acid concentration in rain causes an exposed iron surface to rust more quickly. Which of the following is not a mechanism by which dissolved acid accelerates rusting?

  • AMetallic iron is made more soluble by a decrease in pH.
  • BHydrogen ions react with iron and oxygen to form iron ions.
  • CThe products of rusting are made more soluble by a decrease in pH.
  • DHydrogen ions react with protective surface coatings.
  • EDissolved ions increase the conductivity of water.

Q7:

When rust is formed on the surface of iron, it does not prevent further oxidation of the remaining metal. What is the main reason that rust does not behave as a protective coating?

  • ARust forms flakes that adhere weakly to the iron surface.
  • BRust forms a thin layer on the iron surface and is easily dissolved.
  • CRust reacts with metallic iron, catalyzing its own formation.
  • DRust accelerates oxidation by lowering the pH at the iron surface.
  • ERust accelerates oxidation by binding to water in the air.

Q8:

The density of iron is 7.87 g/cm3. When iron is oxidized during rusting, the density decreases to 5.24 g/cm3. By contrast, the density of aluminum is 2.70 g/cm3 and this value increases to 3.99 g/cm3 when the metal is completely oxidized.

What is the percentage change in volume when iron is converted completely to rust? Assume that no water is present at the end of the reaction.

What is the percentage change in volume when aluminum is completely oxidized?

Changes in volume during oxidation affect the amount of cracking caused by oxidation. How do the volume changes of iron and aluminum differ, and what effect does this difference have on the amount of cracking?

  • AAluminum expands less than iron when oxidized, so less cracking occurs.
  • BAluminum expands less than iron when oxidized, so more cracking occurs.
  • CUnlike iron, aluminum contracts when oxidized, so more cracking occurs.
  • DAluminum expands more than iron when oxidized, so less cracking occurs.
  • EUnlike iron, aluminum contracts when oxidized, so less cracking occurs.

Q9:

Vehicles on major roads are found to rust much more rapidly in cold wet countries when the temperature is below freezing. Which factor is most directly responsible for this effect?

  • ASalt
  • BpH
  • CTemperature
  • DOxygen
  • EHumidity

Q10:

What is the name of the most abundant oxide produced by the rusting of iron?

  • AIron(III) oxide
  • BIron(V) oxide
  • CIron(II) oxide
  • DIron(I) oxide
  • EIron(IV) oxide

Q11:

In which of the following environments would rusting of a steel plate occur most rapidly?

  • AOcean floor
  • BFrozen soil
  • CDesert
  • DRain forest
  • ERiver bed

Q12:

Iron(III) hydroxide is a key product of rusting in humid conditions. This solid material forms from dissolved F e 3 + ions, which in turn are formed from solid iron. The reactions involve water, hydrogen ions ( H ) + , and oxygen molecules. Each step of the reaction can be represented using a net ionic equation, which is balanced based on the total charge on the two sides of the equation being equal..

Including state symbols, give a balanced net ionic equation for the formation of F e 3 + ions from metallic iron and dissolved hydrogen ions and oxygen molecules.

  • A 4 F e ( ) + 1 2 H ( ) + 3 O ( ) 4 F e ( ) + 6 H O ( ) s a q a q a q l + 2 3 + 2
  • B 4 F e ( ) + 6 H ( ) + 3 O ( ) 4 F e ( ) + 3 H O ( ) s a q a q a q l + 2 3 + 2
  • C 2 F e ( ) + 4 H ( ) + O ( ) 2 F e ( ) + 2 H O ( ) s a q a q a q l + 2 3 + 2
  • D 4 F e ( ) + 1 2 H ( ) + 3 O ( ) 4 F e ( ) + 3 H O ( ) s a q a q a q l + 2 3 + 2
  • E 2 F e ( ) + 6 H ( ) + O ( ) 2 F e ( ) + 3 H O ( ) s a q a q a q l + 2 3 + 2

Including state symbols, give a balanced net ionic equation for the formation of iron(III) hydroxide from F e 3 + ions and water molecules.

  • A F e ( ) + 3 H O ( ) F e ( O H ) ( ) + 3 H ( ) 3 + 2 3 + s l s a q
  • B 2 F e ( ) + 3 H O ( ) 2 F e ( O H ) ( ) + 3 H ( ) 3 + 2 3 + s l s g
  • C F e ( ) + 3 H O ( ) F e ( O H ) ( ) + 6 H ( ) 3 + 2 3 + s l s a q
  • D F e ( ) + 6 H O ( ) F e ( O H ) ( ) + 6 H ( ) 3 + 2 3 2 s l s g
  • E 2 F e ( ) + 6 H O ( ) 2 F e ( O H ) ( ) + 3 H ( ) 3 + 2 3 2 s l s g

How many hydrogen ions are consumed in total when an atom of iron is converted to iron(III) hydroxide?

Iron(III) hydroxide can be dehydrated to produce a material containing no hydrogen atoms. How many water molecules are removed for every atom of iron in the material?

Q13:

Why does rusting affect iron more than aluminum?

  • AAluminum is protected by a surface oxide layer.
  • BAluminum oxides are less stable than iron oxides.
  • CAluminum is less reactive than iron.
  • DAluminum oxides are less soluble than iron oxides.
  • EAluminum binds to water less strongly.

Q14:

A thin 25.0 kg sheet of iron rusts in wet air containing excess oxygen. The iron is uniformly converted to a single material consisting of iron, oxygen, and water. The material contains 1 molecule of water for every 2 iron atoms reacted.

What mass of oxygen reacts with the iron during this process?

To 3 significant figures, what is the iron content of the product as a percentage of the total mass?

Q15:

Which of the following is not a role played by water when iron rusts in neutral water?

  • AWater reacts with iron to form hydrogen molecules.
  • BWater dissolves oxygen gas.
  • CWater dissolves iron ions.
  • DWater reacts with oxygen to generate hydroxide ions.
  • EWater is incorporated into the final solid material.

Q16:

A shiny iron nail will rust over time. As it rusts, what happens to the total mass?

  • AIt decreases
  • BIt increases
  • CIt stays the same

Q17:

A steel chain submerged in water is susceptible to rusting. What effect is observed if sodium chloride is added to the water to produce a saturated solution?

  • AThe steel chain rusts more quickly.
  • BThe steel chain reacts to produce a sodium-iron alloy.
  • CThe steel chain rusts less quickly.
  • DThe steel chain reacts to form a chloride salt.
  • ENo rusting takes place.
Preview