2007-03-13 08:04:33 · 7 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
In mineralogy, hardness commonly refers to a material's ability to penetrate softer materials. An object made of a hard material will scratch an object made of a softer material. Scratch hardness is usually measured on the Mohs scale of mineral hardness. Pure diamond is the hardest known natural mineral substance and will scratch any other material. Diamond is therefore used to cut other diamonds; in particular, higher-grade diamonds are used to cut lower-grade diamonds.
ref: http://en.wikipedia.org/wiki/Hardness
2007-03-13 16:27:41 · answer #1 · answered by Dr Dave P 7 · 0⤊ 0⤋
Hardness in water is caused by the presence of dissolved calcium and or magnesium salts. These cations form a gritty, insoluble precipitate called scum when soap is added to the water - most inconvenient and costly.
There are two types of hardness - permanent and temporary. Both are caused by dissolved calcium and or magnesium salts. The difference is that temporary hardness is caused by calcium and or magnesium hydrogencarbonate only. These are both unstable at high temperatures decomposing into the insoluble carbonates and blocking pipes in hot water systems. This is called scale and is often also found on heating elements of kettles. Permanent hardness is caused due to the presence of all other soluble calcium and or magnesium salts and does not cause problems with blocking pipes in hot water systems.
2007-03-13 20:17:27 · answer #2 · answered by D 1 · 0⤊ 0⤋
In terms of geology, it means how hard the rock is. It is measured by a scale that uses a certain set of known hardness, such as diamonds and your nails. If you can scratch the rock with it, the rock is softer.
If you are talking about hard water, that determines how man bubles you get from soap
2007-03-13 08:08:21 · answer #3 · answered by Jared P 5 · 0⤊ 0⤋
Hardness is the rating of a materials imperviousness to scratches and other indentations by another.
2007-03-13 08:08:49 · answer #4 · answered by non_apologetic_american 4 · 0⤊ 0⤋
hardness is an expression for things being tough and it may seem rought but honey in this world you gotta learn a few things...you'll figure it out sooner or later!
2007-03-14 17:45:24 · answer #5 · answered by Anonymous · 0⤊ 0⤋
Diamond is hardest surface i know.
2007-03-13 08:42:23 · answer #6 · answered by CLIVE C 3 · 0⤊ 0⤋
In what context?............I need more info
2007-03-13 08:07:42 · answer #7 · answered by ellietricitycat 4 · 0⤊ 0⤋