Chemistry Experiments You Can Do at Home
How can I test the hardness of objects around my house?
- Materials science
Collect several materials of known hardness, examples include (numbers are based on the Mohs scale):
- Fingernail (2.5)
- Penny (3)
- Glass (typically 5.5-6.5)
- Quartz (7)
- Steel (typically 6.5-7.5)
- Sapphire (9)
You can also look for additional items from the list provided at the end of this experiment, or search online for additional objects that have been ranked on Mohs scale of hardness. Of course, you can also choose item of unknown hardness and determine their hardness in this experiment!
- Locate a specimen whose hardness you want to test. Note that you will be attempting to scratch the object, so don’t choose anything too valuable or anything you don’t want scratched!
- Select an object of known hardness from those you gathered, and try to scratch the surface of your sample by pressing it with a tip or edge of the object of known hardness. For example, let’s say you wanted to test a piece of wood. You could try to scratch it with a piece of quartz by pressing the edge of the quartz into the wood.
- Inspect your sample to see if you have made a scratch in it. You may need to feel the surface of the object with your finger to check thoroughly. If your object was softer than the sample of known hardness, there will be a scratch. If it was harder, then there will not be a scratch. Repeat the test a couple of times to verify the result.
- Continue performing the scratch test with various objects of known hardness, until you find two adjacent objects on your list, such as a fingernail (2.5) and a penny (3), in between which the hardness of your sample rests. You will know you’ve found this pair of objects on your list when the harder object of the pair does scratch your sample, while the softer one does not.
- Once you have found this place on the list, you can assert that the hardness of your unknown must lie between that of the two objects of known hardness on the list. For example, if a penny (3) scratches your object, and a fingernail (2.5) does not, your object must have a hardness between 2.5 and 3.
- Talc (1)
- Gypsum (2)
- Calcite (3)
- Fluorite (4)
- Platinum or iron (4.5)
- Apatite (5)
- Orthoclase (6)
- Quartz (7)
- Garnet (7.5)
- Hardened steel, topaz, emerald (8)
- Corundum (9)
- Diamond (10)