Anonymous
Anonymous asked in Science & MathematicsEarth Sciences & Geology · 9 years ago

Why does increasing the pressure on a solid or a liquid have little effect on its volume?

2 Answers

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• 9 years ago
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Because of the molecular structure in solids and liquids, they are considered incompressible. The molecules in gases are free to move around and there is a lot of empty space between the molecules.

The density of air is approximately 1.29 kg/m^3. The density of water is 1000 kg/m^3. The density of ice is approximately 900 kg/ m^3

The volume of the N2 and O2 molecules is about the same as the volume of H2O molecules. 1 mole of a gas at standard temperature and pressure occupies 22.4 liters. 1 mole of liquid H2O is 18 gram, which is 18 ml, which is 0.018 liter. 1 mole of frozen H2O is 18 grams, and the volume is 20 ml, which is 0.018 liter.

For liquid water, ratio of volume occupied = 22.4 ÷ 0.018 = 1244

OR

For ice, ratio of volume occupied = 22.4 ÷ 0.020 = 1120

1 mole of N2 and O2 molecules occupy 1244 times as much space as 1 mole of liquid H2O and 1120 times as much space as ice.

This means there is lot of EMPTY SPACE, between the molecules of N2 and O2 in the air. An air compressor does not compress the molecules, making the molecules smaller. The air compressor just forces the molecules closer together!

In most solids and liquids, there is not much empty space. So you can’t compress them.

• Thomas
Lv 7
9 years ago

Because their atoms are already close together, and if you try and push them even closer they strongly repel each other by electrostatic forces.

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