Easy⏱ time20 min$ cost2
Penny Cleaning Chemistry
A salt-and-vinegar bath strips tarnish off dull pennies and reveals an acid reaction at work.
Start building ↓
Result first
The build
Step 01
Mix the bath
Stir salt into vinegar until it dissolves.
Step 02
Dip a penny
Drop a tarnished penny in and swirl.
Step 03
Watch it shine
In seconds the dull layer lifts off.
Step 04
Compare
Rinse one penny but not another and watch what happens.
Working Principle
The vinegar's acid plus salt dissolves the dull copper-oxide layer, exposing the shiny copper underneath in seconds.
The science behind it
A closer look
Acid attacks the oxide tarnish; an unrinsed wet penny quickly grows blue-green copper compounds as it reacts with air.
Take it further
Variables to test
- 1 Leave a wet penny out — why does it turn green?
- 2 Compare lemon juice vs vinegar for cleaning.
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