Questions tagged [materials]

Material is a general term for a chemical substance or a mixture of substances with certain, well defined physical properties.

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90
votes
8answers
50k views

Is toothpaste solid or liquid?

My teacher didn't answer this properly: Is toothpaste solid or liquid? You can't say toothpaste is a solid because solid material have a fixed shape but toothpaste doesn't. However, you can't say ...
18
votes
2answers
3k views

If you put two blocks of an element together, why don't they bond?

Say you have two lumps or blocks of an element, like lithium for example, say in the form of two bars. Why, when you bring the two bars together so that they touch each other, do they not instantly ...
3
votes
3answers
1k views

pH and materials selction [closed]

I working on the Navy study guide for their nuclear engineering programs and I am not a Chemist. Thus, I have come here to try and develop a better understanding of the subject matter. Why is pH ...
25
votes
3answers
13k views

Which is the densest gas known?

Which is the densest gas known to exist under normal "shirt sleeve" conditions: room temperature, one atmosphere, won't explode on contact with air, won't kill everyone in the building in trace ...
11
votes
3answers
4k views

Which materials/compounds expand in response to cold temperatures?

Which materials or compounds expand in response to cold temperatures? This material or compound should expand at a slow (but constant rate), from about 0–20 months when in the following temperature ...
27
votes
2answers
2k views

What makes Gorilla Glass more durable with each generation?

Gorilla Glass (GG) is one of the most recognizable brands of toughened glasses today, thanks to their marketing and widespread usage in various gadgets and automobile industry. According to Wikipedia,...
22
votes
2answers
35k views

Why does diamond conduct heat better than graphite?

Our teachers made us accept (without any explanation) that diamond conducts heat better than graphite. What is the reason behind this (alleged) fact?
24
votes
1answer
21k views

Why does sunlight cause colors to fade?

If you leave something outside, its colors seem to inevitably fade or bleach due to exposure. Is this due to UV absorption? What sort of mechanism causes this - is it that man-made dyes deform on a ...
16
votes
1answer
3k views

What material are heat bags made of?

I just bought a heat bag from store and it has special property. It is made up of transparent plastic bag and transparent unknown liquid inside when sold. There is a tiny circular metal piece in ...
12
votes
1answer
477 views

Jahn-Teller Metal : The new state of matter

Recently it came in the news that scientists have discovered a new state of matter called Jahn-Teller metal. I tried reading up on it but couldn't understand it clearly. Please explain in simple ...
4
votes
1answer
131 views

What is the limiting value of band gap that makes a material semiconductor?

What is the limiting value of band gap (in eV) that makes a material semiconductor? Or what is the value of band gap that separates insulator and semiconductor?
17
votes
2answers
1k views

Safety in handling of concentrated ammonium fluoride

I recently saw a protocol for extracting organic materials that are bound in the silica matrix formed by diatoms. The extraction protocol used 10 molar ammonium fluoride ($\ce{NH4F}$). I briefly ...
15
votes
1answer
565 views

What chemical characteristics give types of steel their properties?

I am a mechanical engineer, and just like everyone else I had classes on the crystal structure of metals, phase diagrams, and the various heat treatments. However, even after diving back into that ...
10
votes
2answers
747 views

Brass Instrument: Dezincification or just scrubbed off?

I do own a brass instrument (a trombone). The lacquer is damaged. I asked how to deal with it here. Now I learned that the brass contains zinc, and there is a corrosion process called "...
4
votes
1answer
857 views

How does salt dough work?

Sorry for coming in here with little chemistry knowledge and a pretty inane question, but my googling skills have completely failed to cut through the enormous combined output of the baking brigade ...
3
votes
1answer
209 views

What is some advance reference books about alloy that gives a lot historical background and applies a lot of theoretical equation or formulas

What is some advance reference books specifically about alloy that gives a lot historical background and applies a lot of theoretical equation or formulas with explanation? I seem to find nothing ...
3
votes
2answers
176 views

How do we determine if some metal will undergo passivation under suitable environment?

The passivity of certain metal fall in order: $\ce{Ti->Al->Cr->Be->Mo->Mg->Ni->Co->Fe->Mn->Zn->Cd->Sn->Pb->Cu}$ Can we predict the order of passivation ...
2
votes
3answers
2k views

Does crystalline glass exist?

As far as I know, glass is a non-crystalline amorphous solid. Does glass exist in crystalline forms? Or is it the definition of glass that it's non-crystalline, in which case my question is based off ...
2
votes
2answers
95 views

Looking for a chemical to calibrate a temperature sensor

The best method for calibration would be a bath filled with a chemical at its melting point with a solid/liquid composition. The constraints being that it must be hydrophobic and relatively non-...
1
vote
2answers
241 views

Chemistry Self Education [closed]

I want to learn chemistry. I did not have the benefit of studying it when I was in highschool, and I was always intimidated by it (I feel it's more rote memorization rather than understanding - I'm ...