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Chemical equation for pickling of steel with acid

March 22, 2010

to whom it may concern:

I am doing a science project and I am wondering what the balanced chemical equation for "pickling" steel with hydrochloric acid is and what kind of reaction (eg. synthesis, single displacement etc.)

(grade10)

Bob B
student - Dundas, Ontario, Canada

Hi, Bob. Steel is very hot when melted, cast or rolled; and this hot steel will have reacted with oxygen in the air to form non-useful scales/rusts on its surface that must be removed. I would expect this scale to be all of the forms of iron oxides, so look up iron oxide and find at least two chemical forms. The steel is usually passed through "scale breaking" rollers that crack this scale in order to minimize what must be done chemically, and to give a lot of surface area and good penetration through the scale so that the HCl will dissolve it quickly. Then the steel is immersed in the HCl and the HCl dissolves the iron oxides to remove them. That process is called pickling.

Now that you have an understanding of what it's about, I'll leave you to write the reaction formulas for iron oxide and HCl, and let you name what kind of reaction it is. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 23, 2010