The force between two non-reacting atoms is approximately given by the Lennard-Jones potential , and this varies with the separation of the atoms something like this:. When the atoms are far apart there is a very slight attraction, but as soon as the atoms come into contact there is a strong repulsion and it's very hard to push the atoms any closer together.
Be cautious about taking this too iterally as atoms are somewhat fuzzy objects and don't have an exact size. Now back to your question. This means the average spacing between molecules is around 3nm.
The size of an oxygen molecule is very roughly they aren't spherical 0. That's way off to the right on the graph above, and it means the forces between them are low and it's very easy to push them together. This is why gases can be easily compressed. Now conside water. One mole of water 0. This is the point where the molecules start to repel each other stringly, and that makes it hard to push them closer together.
That's why water is not easily compressed. You ask about compressing a mixture of unreacted oxygen and hydrogen. This makes the spacing between oxygen molecules about 0. However a quick Google failed to find values for the bulk modulus of liquid hydrogen. So liquid water is about times denser then gas. When you compress liquid water together, the molecular forces become very strong stopping it from being compressed very much.
However, for a gas the molecules are so far apart that the forces are much smaller the main reason a gas can't be compressed is due to the kinetic energy of the molecules in the gas.
The basic model of a gas that individual gas particles don't interact. As in: there's enough space between molecules, such that they spend most of their time travelling in straight lines, without bumping into each other i.
Think of two bottles: One bottle is entirely full of water — you can't blow air into this bottle. Objectives Investigate the properties of liquids and gases. Describe the relationship between pressure and force.
Materials two identical bottles one-holed rubber stoppers or corks that fit tightly in the bottle necks glass, plastic or copper tubing that fits snugly through the hole copper tubing and a tube cutter can be purchased at a hardware store Key Questions Why does the water from the bottle spray you when you pull the straw out? What To Do Fill one bottle entirely with water and insert the stopper.
Fill the second bottle with water, leaving 5 or 6 cm of air at the top. The tubing should stick down into the water when you put the stopper in. Pick two student volunteers and give each one a bottle. They each blow as hard as they can into the straws.
Each water molecule can form up to four of these hydrogen bonds and, collectively, they give water a cohesiveness unique in liquids. This explains why water is a liquid on the surface of the Earth: the hydrogen bonds hold the molecules together in such a way that more energy than normal is needed to separate them, for example if you want to boil the liquid into a gas. They enable water molecules to pull each other through the tiniest blood vessels in your body — often working against the force of gravity — carrying oxygen and nutrients to parts that would otherwise be hard to reach.
All these things are possible because water is difficult to compress — the molecules attract each other and, in their natural state, tend to stay closer together than the molecules in other liquids. The harder something is to compress, the easier it is to move it around if you apply a pressure to one side of it. Water is not only attracted to itself but will stick to almost anything else it comes across.
It is the closest thing we have to a universal solvent, able to tear apart other compounds. Common salt, which is made up of crystals of sodium chloride, easily dissolves in water because the hydrogen bonds pull the sodium and chlorine atoms away from the crystal, leaving them to float freely through the liquid.
Water is such a good solvent, in fact, that it is almost impossible to find naturally in a pure state; even producing pure samples in the laboratory is difficult.
Almost every known chemical compound will dissolve in water to a small but detectable extent. Because of that, water is one of the most reactive and corrosive chemicals we know. That ability to interact with so many things is crucial for life. It means that water can dissolve a wide variety of nutrients and other ingredients and move them around our bodies.
Evolution has shaped these long, sophisticated molecules so that they have certain sections that easily mix with water, using hydrogen bonds, and other sections that shun water, like oil refusing to mix.
The billions of protein molecules inside your body only fold into the right shapes to do their jobs because their interaction with water nudges them into the correct three-dimensional formats. Think of a liquid and it will most likely be water.
Water is so common and so familiar that it is mundane: every day we drink it, touch it, wash with it, wet things, dry things, we boil it, freeze it and swim in it.
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