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Thermal Physics
Why a Gas Exerts a Pressure
Consider the molecules of a gas moving at random in a container, as shown below.
The molecules are continually colliding with each other and with the walls of the container. (On the diagram, only a few paths of molecules have been drawn because...it’s a bit tedious drawing them!) It is assumed that all collisions are elastic. (Consider what would happen if the collisions were not elastic.) When a molecule collides with the wall, a change of momentum occurs. The change in momentum is caused by the force exerted by the wall on the molecule. The molecule exerts an equal but opposite force on the wall. The pressure exerted by the gas is due to the sum of all these collision forces.
Why the Pressure Exerted by a Gas Increases as the Temperature Increases
If the temperature of the gas is increased, the average kinetic energy of its molecules increases. Therefore, the molecules hit the wall "harder" and also more frequently. The total force due to the collisions is greater. Therefore the pressure increases.
Links to:
The Kinetic Theory of Matter
Why the Temperature of a Gas Increases when it is Compressed
Distribution of Molecular Speeds
Thermal Physics Chapters Index
Return to top of page synthesis of potassium permanganate (KMnO4), a common chemical. Occasionally, potassium manganate and potassium permanganate are confused, but they are different compounds with distinctly different properties.
Contents [hide]
1 Structure
2 Synthesis
3 Reactions
4 Literature cited
5 Other references
6 External links
Structure[edit]
K2MnO4 is a salt, consisting of K+ cations and MnO42− anions. X-ray crystallography shows that the anion is tetrahedral, with Mn-O distances of 1.66 Å, ca. 0.03 Å longer than the Mn-O distances in KMnO4.[1] It is isostructural with potassium sulfate.
Synthesis[edit]
The industrial route entails treatment of MnO2 with air:
2 MnO2 + 4 KOH + O2 → 2 K2MnO4 + 2 H2O
The
Why a Gas Exerts a Pressure
Consider the molecules of a gas moving at random in a container, as shown below.
The molecules are continually colliding with each other and with the walls of the container. (On the diagram, only a few paths of molecules have been drawn because...it’s a bit tedious drawing them!) It is assumed that all collisions are elastic. (Consider what would happen if the collisions were not elastic.) When a molecule collides with the wall, a change of momentum occurs. The change in momentum is caused by the force exerted by the wall on the molecule. The molecule exerts an equal but opposite force on the wall. The pressure exerted by the gas is due to the sum of all these collision forces.
Why the Pressure Exerted by a Gas Increases as the Temperature Increases
If the temperature of the gas is increased, the average kinetic energy of its molecules increases. Therefore, the molecules hit the wall "harder" and also more frequently. The total force due to the collisions is greater. Therefore the pressure increases.
Links to:
The Kinetic Theory of Matter
Why the Temperature of a Gas Increases when it is Compressed
Distribution of Molecular Speeds
Thermal Physics Chapters Index
Return to top of page synthesis of potassium permanganate (KMnO4), a common chemical. Occasionally, potassium manganate and potassium permanganate are confused, but they are different compounds with distinctly different properties.
Contents [hide]
1 Structure
2 Synthesis
3 Reactions
4 Literature cited
5 Other references
6 External links
Structure[edit]
K2MnO4 is a salt, consisting of K+ cations and MnO42− anions. X-ray crystallography shows that the anion is tetrahedral, with Mn-O distances of 1.66 Å, ca. 0.03 Å longer than the Mn-O distances in KMnO4.[1] It is isostructural with potassium sulfate.
Synthesis[edit]
The industrial route entails treatment of MnO2 with air:
2 MnO2 + 4 KOH + O2 → 2 K2MnO4 + 2 H2O
The
Links: Jump up ^ Nyholm, R. S.; Woolliams, P. R. (1968). "Manganates(VI)". Inorg. Synth. Inorganic Syntheses 11: 56–61. doi:10.1002/9780470132425.ch11. ISBN 978-0-470-13242-5.