Why does vinegar and salt clean pennies?
William Rodriguez
Published Jan 18, 2026
The combination of vinegar (a weak solution of acetic acid), and table salt (sodium chloride) helps to dissolve the copper oxide, and also forms the blue copper(II) ion, which is soluble in water. The penny becomes shiny again!
How does vinegar and salt clean pennies?
Start by adding a quarter cup of white vinegar, or lemon juice, into a cup or glass. Mix a teaspoon of salt into the liquid by stirring until it is dissolved. Place your pennies at the bottom of the cup or glass so that they are not stacked on top of each other. Wait about five minutes and check your pennies.Is cleaning a penny with vinegar and salt a chemical reaction?
When the salt and vinegar are combined, they form a very small amount of hydrochloric acid. This acid removes oxidation from pennies. Removing the copper oxide is a chemical change. The copper molecules in the vinegar and salt solution settle on paper clips after a period of time, but wipe off easily.What happens when you soak pennies in vinegar?
The vinegar made its penny shiny. Pennies become dull over time as copper on the surface reacts with oxygen from the air. The two elements combine to form dark chemicals called copper oxides. The acetic acid in vinegar dissolves these chemicals and leaves the copper surface of the penny looking shiny.Why does Coke clean a penny?
The soda cleans the pennies because it contains phosphoric acid. Phosphoric acid breaks down the copper oxygen compound and causes a new layer of the copper to be exposed.Clean pennies with Vinegar and Salt
Why does a penny turn green in vinegar?
A penny is made of copper. The vinegar on the paper towel helps the copper in the penny easily react with the oxygen in the air to form a blue-green colored compound called malachite.Does Coca Cola clean coins?
Who would have thought that your favorite soda is also a great cleaning agent? Yes, that refreshing can of Coke that you like to drink by the pool can also clean coins. Coke's phosphoric acid can clean the oxides that cause tarnish and corrosion.Why do pennies turn black in vinegar?
As they are exposed to the environment, pennies become coated with a layer of copper oxide, making them look tarnished (with a dull, brown, dirty appearance). Copper oxide dissolves in a mixture of weak acid and table salt. Vinegar and lemon juice are both acids.What is the science behind cleaning pennies?
The oxygen in the air and the copper in the pennies form an oxide that coats the pennies and makes them look dirty. The acids (usually vinegar - acetic acid) break the copper oxide free from the penny.Why does vinegar dissolve copper oxide?
Copper atoms can combine with oxygen atoms from the air to make a molecule called copper oxide. The pennies looked dull and dirty because they were covered with copper oxide. Why did the vinegar and salt clean the pennies? Copper oxide dissolves in a mixture of weak acid and table salt-and vinegar is an acid.How long do you leave pennies in vinegar?
Let the pennies sit for 20-30 seconds.The vinegar and salt duo will act fast, so there's no need to leave them in for too long. As the pennies soak, you should be able to notice the dark colored tarnish and other gunk melting away from the copper before your very eyes.