Corrosion

Topic 10 - Using Resources
Written By Atheridge Tuition

Four test tubes are left for two weeks to investigate corrosion. Predict and explain the appearance of the nail in each tube after two weeks.

  • Tube 1: Pure iron nail exposed to air and water.

  • Tube 2: Pure iron nail submerged in boiled water with an oil seal layer.

  • Tube 3: Pure iron nail in dry air with a drying agent.

  • Tube 4: Stainless steel nail exposed to air and water.

[4 marks]

Visual Mark Scheme Breakdown

    • Water AND Oxygen

Minimalist graphic showing Iron (Fe) plus Water as a blue drop plus Oxygen as a circle with its formula giving Rust.

    • Tube 1 has both air and water.

    • The nail rusts.

    (1 mark)

Tube 1 with an iron nail inside water and exposed to oxygen. Text reads Rust? with a tick.

    • Boiled water removes dissolved oxygen.

    • Oil seal prevents any oxygen coming in.

    • No oxygen means NO rust.

    (1 mark)

Tube 2 with an iron nail inside boiled water and an oil seal. A water droplet indicates the nail is exposed to water. Text reads: Oil layer prevents oxygen. Boiled water removes oxygen. Rust? a cross.

    • Drying agent absorbs moisture.

    • No water means NO rust.

    (1 mark)

Tube 3 with a nail and drying agent. A circle with oxygen formula indicates the nail is exposed to oxygen. Text reads: Drying agent absorbs water. Rust? with a cross.

    • Tube 4 has a nail made from Stainless steel. So it contains chromium which does NOT corrode.

    (1 mark)

    Remember, the word rust is only for iron.

Tube 4 with stainless steel nail in water. Water droplet with water formula and circle with oxygen formula inside indicate presence of both. Text reads: Stainless steel does NOT corrode. Rust? with a. cross.
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