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What causes vinegar to form less rust than water?
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Hello, thank you for listening. I'v read these questions and answers and none of them have told me anything I need to find out about my project that I'm doing. So far none of he questions or answers have anythingto do with what I'm about to ask. Why is the vinegar the one that causes less rust on the nail than the water. I know every thing about the oxidation and how that plays a major part in the water being the one that causes the more rust but, why does the vinegar the one that causes the least rust. I really don't get it because I've researched it and I still don't get it and the quetions and answers here haven't helped me a bit so I was wondering if u could help me out a little bit more. Is there something in the vinegar that causes less rust to form or what? please help try to get back to me a.s.a.p. thank you very much!
Mar I.science project - Staten Island , New York
First of two simultaneous responses -- ++++
Mar,
You spent a lot of time telling us what you know, but not much on what you're doing. So I'll make some assumptions. You had two completely identical nails. You poured some vinegar into a container and covered a nail. You did the same with some tap water.
It's hard to say for sure, without seeing your setup and being able to measure things, why you got more rust on the water nail, because all else being equal one would expect a more acidic solution to have a higher corrosion rate. However, the tap water probably had a lot of dissolved oxygen and the vinegar would have less. Most faucets aerate the water that comes out. Oxygen is crucial to the reactions that include the dissolution of iron, or of zinc if your nails were galvanized (meaning coated with zinc).
The electrons generated when iron corrodes have to go somewhere, and that somewhere is usually a reaction including oxygen. Depending on how full the containers were when you started, whether they were protected from or open to the atmosphere, the ease of getting oxygen into the solution would have varied. Hope that this helps some. You could try things over with water that has been boiled and then cooled without agitation, which will reduce its oxygen content. Also make sure that the nails are identical and have been cleaned identically.
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Paul Tibbals, P.E. |
Second of two simultaneous responses -- ++++
I'm impressed you know everything about oxidation! I know lots of people who know they don't know as much about it as they would like, so perhaps they can ask you! Seriously, the reason vinegar doesn't rust as much as water is because vinegar is acidic (acetic acid) and this dissolves the metal, along with its oxides, leaving a clean surface. Since the salts it produces dissolve in the vinegar, you often don't easily see them. On the other hand, water is not so acidic, so it corrodes, or rusts, the metal to form an oxide or hydroxide; with iron, this usually appears as a brown mess. To prove the point take two samples of iron and weigh them. Then put one of them into water and the other into vinegar. Leave the for a week and take them out. Carefully wash and dry them and then re-weigh them. Tell us what you find.
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Trevor Crichton R&D practical scientist The Pheasantries - Chesham, U.K. |