? 發問於 科學及數學化學 · 1 十年前

chem~~~~^^ ten marks !!!

essay

Protective coatings are commonly used for rust prevention. Discuss the underlying principle involved and describe THREE kinds of protective coating and their limitations, with reference to specific examples.

(You are required to give a paragraph-length answer. In this question, 8 marks will be awarded for chemical knowledge and 3 marks for effective communication.)

1 個解答

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  • 1 十年前
    最愛解答

    Protective coating is to coat the iron with sometihng to keep out the water and oxygen to prevent it rusts.

    Three kinds......

    1.Tin plating:It prevents the iron contact with air, but when the coating is destroyed, the rusting will occur, because tin is less reactive than iron.

    2.Zinc plating:It prevent the iron contact with air, but when the coating is destroyed, rusting still not occur, because zinc s more reactive than iron, so the zinc can do satisifical protection, the limitation is that zinc is poison.

    3.Coating with paint:It prevent the iron contact with air,it's a very cheap and simple way,but when the paint is scratched,the iron contact with air and start to rust.

    資料來源: 自己~
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