# Tag Info

Accepted

### Is toothpaste solid or liquid?

Toothpaste is what is called a non-newtonian fluid, more specifically toothpaste is a Bingham plastic. This means that the viscosity of the fluid is linearly dependent on the shear stress, but with ...
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### Which "exotic salt" can lower water's freezing point by 70 °C?

I recently got a chance to attend a talk by someone who was working on developing analytical instrumentation on Mars. The interesting story is that the initial results by ion-selective electrode was ...
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### What is the pH of ice?

According to Martin Chaplin's Water Dissociation and pH: In ice, where the local hydrogen bonding rarely breaks to separate the constantly forming and re-associating ions, the dissociation constant ...
• 38.8k
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### Is there a cheap, safe liquid that evaporates EXOthermically around room temperature?

No such liquid, safe or otherwise, can exist. Evaporation is a strictly endothermic process in all cases. The change in state from liquid to gas is marked by the individual particles gaining enough ...
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### Is toothpaste solid or liquid?

Here's a genchem-level answer for a genchem-level question about the classification of matter: Toothpaste is a sol: a stable suspension of tiny solid particles in a liquid. When the toothpaste dries ...
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### How does water evaporate completely when at room temperature?

As your small percentage of molecules with high enough kinetic energy evaporates, the remaining liquid water cools down. But in doing so, it drains heat from its surroundings and thus stays at room ...
• 29.6k
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### A glass of water with ice-cubes in it. Where's the water the coldest; at the top or bottom?

Interesting question! A few things first: As the ice melts, it cools the water around it. Technically, the ice cube melts because the water cools down. This may sound ridiculous at first, but you ...
• 17.9k
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### What happens if you cool water in a container too small for it to freeze?

Good question. Let's assume the container is infinitely strong, non-deformable, and constant in volume. Let's also assume that cooling the water is an equilibrium process -- that way, we won't have ...
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### At what pressure will hydrogen start to liquefy at room temperature?

$\ce{H2}$ cannot be liquified at room temperature, whatever the pressure. Generally speaking, all gases can only be liquified when the temperature is under its critical value.
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### Molten vs Liquid

As you said, the meaning is exactly the same. Molten reduces the ambiguity, because you emphasize that you know, that it is solid substance at laboratory conditions and you heat it to become liquid (...
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### At what pressure will hydrogen start to liquefy at room temperature?

The critical temperature of Hydrogen is $\pu{32.938 K, resp. -240.21 ^{\circ}C}$. Above this temperature, it cannot be liquified. So to answer your question, you can get as high pressure as you can ...
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### Is toothpaste solid or liquid?

Here's the boring answer: Toothpaste is a mixture of some solids and some liquids. The question "is it solid or liquid?" makes sense when you're talking about a substance or a mixture with a single ...
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### Why does liquid water form when we exhale on a mirror?

Why do we have water vapors when our body temperature is also <100°C in the first place? At normal pressure, water boils at 100°C, meaning that bubbles of pure steam form under water. At lower ...

### Why does gas not liquify at a temperature above the critical temperature no matter how much pressure is applied on it? Why?

It really does liquefy. But it does not do so in exactly the same way as you see below the critical temperature and pressure. As an example, suppose you heat steam to 400°C and then compress it, ...
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