been helping a child with this project, it is not easy to find information at the library or on the web on this subject; any help these kids can be given is in need. Background info on what metals can be affected by what acids is next to impossible to find, and what those affects will be I can't find anywhere. ask.com, yahooeducation.com, and channel4.com have been of some help.Brandy T
- St. Louis, Missouri
You didn't mention what grade your child is in, but a good starting point might be a high school chemistry text. It will explain in detail exactly what acids are, how they work, and why. Most acids quickly dissolve active, light, metals like aluminum, magnesium, and zinc by putting the metal into solution as an ion. They will act more slowly on iron (steel). Most acids will remove tarnish from more noble metals like copper, by dissolving the oxides into ions, while not having the power to oxidize and dissolve the metal itself. Most acids will have no effect on gold (aqua regia, a mixture of hydrochloric and nitric acid, being the exception). Nitric acid is an oxidizing acid (both an oxidizer and an acid) and its effects are stranger--it will dissolve metals like copper, which simple acids won't; but it will not dissolve aluminum, which simple acids will.
For younger students, I personally don't see value in rote memorization of the effects of various acids on various metals -- they haven't yet had chemistry so they will not gain any insight. What the younger students should be learning (in my opinion, but who am I) is the "method" of doing science experiments and projects. And this is about forming a hypothesis, distinguishing between observation, guesses, and conclusions, keeping a lab book and writing everything down, never erasing a single word, and how to do research. For me or anyone to simply respond that such & such an acid will do so & so to such & such a metal doesn't seem to me to get to the heart of the desired learning experience.
If a science project would benefit from input by people involved in metal finishing, our readers usually leap cheerfully to help, and you'll see hundreds of examples on these pages! But it isn't within our power to clarify a homework assignment, to make up for a poor selection of books in the school library, or to answer homework questions for millions of students around the world. Further, teachers are constantly imploring us to: "Just tell the students to do their own homework!"
I couldn't agree with you more about the fact that kids try to take the easy way of finding answers. However, I have been to my local library for research questions only to find that the resources are out of date or do not go in depth enough. Then I was directed to go on line for answers. My son thought he hit a gold mine when he found all those responses and left them for me to read. I told him he had a wealth of info and to come read! He was looking for the effects of phosphoric acid on metals. His science project though stemmed from Coca-cola and the effects it had on various materials. So possibly the boy who originally asked the question might have had a broader topic. My son's teacher told him to look up acids and the effects they have on metals. That is how we got to this site.Suzy C
- Raymond, Maine
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September 21, 2008
What common acids (Lemon juice, vinegar, orange juice) will have the most effect on metals? I am a 6th grader and I am doing a science project and I have to ask a person or expert and I don't know where to go.David H
6th grade student - Apple Valley, California
September 24, 2008
Hi, David. Your question isn't tightly enough framed yet, because you haven't defined what you mean by "effect" (discolor? remove tarnish? corrode holes through? rust?) and you haven't yet specified the particular metals (for example, none of these will have any effect at all on gold).
But in general, vinegar or lemon juice will remove tarnish from copper, remove rust from steel, and corrode zinc. I don't know about orange juice