Activity: Test Like An Alchemist
Can the solution mixture in the first lesson be saved and reused?
We haven’t tried keeping these solutions long-term, but there’s no reason why they shouldn’t last or be just as effective several weeks, or even months, down the road since they’re essentially cleaning and pickling solutions.
The one exception to this is the vinegar and salt solution students will use to soak the pennies overnight. Do not leave these pennies soaking long term or reuse this liquid. For the vinegar and salt solution for Station 3, you will need to make a new solution for each class.
However, if you want to prepare everything at once and have multiple containers, you could mix enough vinegar and salt solution ahead of time for all your classes, as long as it isn’t reused after the pennies have soaked in it.
The pennies didn't get shiny. Any suggestions?
Here are some tips that may help:
- Be sure to add the salt to the vinegar; it’s this combination that makes the experiment work.
- Pennies need to be brown, not blue-green. The blue-green color is a different type of oxidation that the vinegar and salt mixture won’t clean.
- Make sure you are using steel nails. If you’re not sure, you can check the package or product description, or ask a store clerk. We've also started using large steel nails since they are less expensive and tend to be regular steel. We've found that the pure steel nails tend to be longer in size, and typically are sold loose rather than in tubs or boxes. Some teachers have also had success with removing the zinc from a galvanized nail by soaking it in vinegar overnight, which could also be done as an additional experiment!
If I use paper clips instead of nails, and take them out of the solution in the morning and wipe them down, will they stay copper-plated until next week?
The paper clips should stay copper-plated, but be careful when wiping them down! It turns out that the copper is only a thin layer on the surface, so it could possibly be wiped off. If you're trying to dry the paper clips, gently pat them with a napkin or paper towel.
What can I use if I’m having trouble finding old pennies?
Our first suggestion would be to ask your students to check with their parents and bring in any old pennies they can find. Many teachers have had success in collecting enough old pennies this way!
If you and your students are unable to find pre-1982 pennies, copper washers can be a good alternative. The washers may not work very well for the first lesson, since they probably won’t be as dirty as the old pennies, but they should work well for the second lesson when they react with vinegar.
Will zinc-plated steel washers work?
Galvanized or zinc-coated nails or washers will work if you remove the galvanized coating first. We’ve found that you can do this by soaking them in vinegar overnight! After they have soaked overnight, rinse them and wipe them off to remove any residue. Then you can use these nails or washers for the copper nail experiment.