RUSTING

Corrosion of metal is a redox reaction

• Yes

• No

Rusting occur in the presence of

• oxygen

• water

• hydrogen

During rusting, iron undergoes oxidation to form

• water

• Hydroxide ion, OH^-

• Iron(II) ion, Fe²⁺

• Iron, Fe

which one is the correct equation for reduction during rusting?

• Fe --> Fe²⁺ + 2e

• 4OH^- --> O₂ + 2H₂O + 4e

• Fe²⁺ + 2e ---> Fe

• O₂ + 2H₂O + 4e ---> 4OH^-

The function of phenolphthalein is to detect the presence of

• Fe²⁺

• H₂O

• OH^-

• Fe

The function of potassium hexacyanoferrate(III) solution is to detect the presence of

• Fe²⁺

• H₂O

• OH^-

• Fe

When Iron in contact with magnesium, which one corrode first?

• Iron

• Magnesium?

Why Iron corrode first when in contact with copper?

• Iron is less electropositive than copper

• Iron is more electropositive than copper

How can we control metal corrosion?

• Alloying

• Galvanising

• Sacrificial protection

• Expose to sunlight

The correct formula for rust is

• Fe(OH)₂

• Fe

• Fe(OH)₃

• Fe₂O₃.xH₂O