The finishing.com Hotline: Serious Education ... plus the most fun you can have in metal finishing. Ted Mooney, Webmaster
The Effects of Acid on different kinds of metal
I'm doing a science fair project on the affects of acid on different kinds of metal. I would like some information on this.
Thanks,Jake B. [last name deleted for privacy by Editor]
high school student - Meridian, Mississippi
Hi, Jake. You are posing the question rather vaguely, so it seems that you don't feel especially enthusiastic about this project yet and haven't yet been to the library on this. Your school or town librarian should be able to help find books for you on interesting science projects and on acid attack on metal. I think that is the first step.
If your library trip doesn't pique your curiosity about some specific aspect of this that you'd like to address, maybe the teacher will let you change the project to something you would enjoy more? Enthusiasm is key to a worthwhile project -- you have to be interested in learning the results.
For a "routine" project, pick some dilute common acids hopefully available in your high school lab like hydrochloric, sulfuric, phosphoric, acetic, and nitric; and pick some common metals like steel, zinc, copper, and aluminum. Conduct tests under the supervision of the chemistry teacher or lab assistant. Obviously these acids can be hazardous and this part of the project must be done in the lab; unfortunately, you can't put the acid on display on project night, but you can certainly display the corroded metal.
Later you can flesh this out the subject by searching the internet for hits containing both the acid name and the metal name. Good luck!
Ted Mooney, P.E. RET
Pine Beach, New Jersey
What Ted says makes sense. But YOU have to chose WHICH acid you want to write about.
Why? Because some acids attack some metals and others don't. And mixtures of acids can be very aggressive!
So start with, say, Hydrochloric (sometimes called Muriatic) or Sulphuric.
Go to GOOGLE and try to get data on corrosion resistance of metals on the acid of your choice. OK?
And to prove to your teacher wotta good pupil you are, mention Aqua Regia (King of Waters) which dissolves gold. What is it? Look it up, Jake !
- White Rock, British Columbia, Canada
(It is our sad duty to advise that Freeman passed away April 21, 2012. R.I.P. old friend).
Take it from a parent that has 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 [last name deleted for privacy by Editor]
- 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!"
Ted Mooney, P.E. RET
Pine Beach, New Jersey
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 [last name deleted for privacy by Editor]
- Raymond, Maine
Award Winning Science Fair Projects
Solar Energy Projects for the Evil Genius
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 [last name deleted for privacy by Editor]
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.
Cut some post-1982 pennies into tiny pieces to expose the zinc core and leave them in these three materials for a week and see what effect you discover. Good luck.
Ted Mooney, P.E. RET
Pine Beach, New Jersey
November 4, 2008
My son is also doing a science fair project using different pH's to see the effect they have on the rate of oxidation of copper and iron. We are removing the metals from their test tubes for 1/2 hr daily in order for the oxidation to occur. I'm just trying to verify that our results are correct thus far. It seems our iron isn't faring too well in the lower pH's but both the copper and the iron seem to be faring the best in the highest pH. Is this correct? Just trying to make sure we haven't goofed somewhere along the way.Sharon Kleszynski
- Manteno, Illinois
November 7, 2008
Hi, Sharon. Science is different than spelling or arithmetic; the object is not for your son to get the "right" answer like in spelling or arithmetic. The object is to learn how to form a hypothesis and to develop a test procedure that tends to confirm or disprove the hypothesis. You set up a test procedure, you honestly and accurately record your observations, and then you can try to understand and explain those observations. But your observations are non negotiable! You never ever change them even if the teacher and every other student got contrary results.
It is actually better if he doesn't know the results to expect, because then he won't be tempted to discount what he has seen, or repeat things until it turns out "right" due to some random event. If he feels pressure to get the "right" answer, he will be tempted to practice "junk science".
It really is important for him to understand the critical difference between things he has observed and his possible explanations for what he sees. Get a composition book =>
If he starts writing "... because the copper metal is being converted to copper sulphate", stop him -- because he didn't observe that, he is presuming that. He should save explanations of why until after the experiment is complete.
If he learns to clearly differentiate between what he has actually observed vs. people's theories for why it happened, the project has been a huge success. If he learns to fudge his observations just a little bit so it's easier to arrive at the popular conclusions, the project was a disaster. Best of luck!
Ted Mooney, P.E. RET
Pine Beach, New Jersey
August 2, 2009
I have recently done the same sort of thing.
I had to conduct an experiment which explored whether acids or bases had a larger effect on metals. I decided to conduct an experiment that tested corrosion.
I used un-galvanised steel, a very simple and cheap product. (I purchased small corrugated pieces in a packet from the hardware store).
The acids and bases that I used were simple household ones such as acids- vinegar, lemon juice. and bases- ammonia and shampoo.
This experiment, although simple as it is, provided excellent results that I was able to assess and discuss very successfully. It was also very cost-efficient and could be conducted in my own time because it wasn't dangerous. All of the materials were so easily accessed.
Household acids have a high corrosive affect on metals!
- Sydney, Australia
opinion! April 16, 2011
I stumbled across this page because I'm doing some research on dissolving powder coatings on metals without destroying the integrity of the substructure. The postings didn't really apply to my situation but I figured I would add my two cents to the subject. Ted, I agree with everything you have said and it is all completely true in my eyes. I graduated a couple years ago with a BS in Mechanical Engineering so I have had a decent amount of schooling. Learned a lot of great things, learned a lot of useless trivia, also forgot a lot.
I recently tried to soak a wheel in muriatic acid to dissolve the existing powder coating. Found out that I had committed a huge brain fart when I pulled the HOT wheel out of my smoking tub of acid. Completely forgot about how acids affects metal, especially strong acids like hydrochloric.
One experiment that has fascinated me ever since I saw it, was the separation of hydrogen and oxygen (electrolysis of water). It was done by the teacher my freshman year in high school because it was considered 'dangerous'. It wasn't dangerous, it was inspiring. I didn't learn testing procedure or how to list my observations correctly, what I learned was how to extract hydrogen and it stuck with me ever since. I agree that process and procedure is important to learn but they should be learned with experiments. Experiments are done because the end result is unknown and if that's what you are trying to do then you need to listen to everything Ted has mentioned above. If you are not testing for the unknown but instead demonstrating the awesome power of science then maybe a different approach should be considered. Seems like these postings were related to younger kids in elementary school. Kids in elementary school don't give a rats a** about proper procedure, they want to see cool things happen. Teachers should be spending their time and efforts trying to capture young minds and teach them science. Science has been around for a long time. There's no need to continuously derive how F=ma -- Newton did it a long time ago and it makes sense. Lets go with it. There's plenty of time to teach kids proper procedure in high school and college when their minds are more capable of handling dull subjects.
Here's my opinion for demonstrating the effects of acid. This should be done by an adult, an adult that knows what they are doing, or is at least capable of knowing how to handle when it goes bad. Take a tub of hydrochloric acid and put some steel in it and let the kids witness the power demonstrated by the acid on the wheel. Unfortunately I know for a fact, it's not a joking matter. I could have sent smoke signals with the reaction I had going on.
Go big or go home. Nobody cares how lemon juice changes the color of a penny, nor will the kid remember it 15 years later when he's dumping wheels into hydrochloric acid. Teach these kids real science. If you don't know science, but are instead hunting for answers on a website, then maybe you should do some learning before teaching today's youth. My best teacher in high school wasn't a teacher, he was a scientist. Luckily he knew how to communicate his knowledge in an acceptable manner. But let's also face the fact that some dogs just won't hunt. In other words, some kids aren't going to care no matter what.
- Wilmington, North Carolina, USA
Disclaimer: It is not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous; some names may be fictitious and some recommendations may be deliberately harmful.
If you need a product/service, please check these Directories: