10TH GRADE · MOLECULAR KINETIC THEORY
Ideal gas and isoprocesses
Gas pressure, temperature, equation of state and gas processes.
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Basic Concepts
Basic MKT equation
Relationship between the pressure of an ideal gas and the concentration, mass and average energy of particle motion.
Macroscopic pressure arises from the many impacts of molecules against walls; it increases when there are more particles or they move faster.
Absolute temperature
Temperature on the Kelvin scale related to the average kinetic energy of particles.
The gas laws use only kelvins: absolute temperature is directly related to the average kinetic energy of the particles.
Ideal gas equation of state
Relationship between pressure, volume, temperature and amount of substance in an equilibrium ideal gas.
For a given amount of ideal gas, the parameters p, V and T cannot be changed independently: changing two determines the third.
Isoprocess
A gas process in which one of the state parameters remains constant.
Before choosing a law, you need to determine a constant parameter: temperature, pressure or volume. The type of connection between the remaining quantities depends on this.
Physical quantities
Mean square speed
The average value of the square of the particle velocity.
Unit: square meter per square second ·
Average kinetic energy of a particle
Average energy of translational thermal motion of a particle.
Unit: joule ·
Boltzmann's constant
Coefficient of connection between absolute temperature and particle energy.
Unit: joule per kelvin ·
Absolute temperature
Temperature measured on the Kelvin scale.
Unit: kelvin ·
Temperature Celsius
Temperature measured on the Celsius scale.
Unit: degrees Celsius ·
RMS speed
Root of the mean square of particle speed.
Unit: meter per second ·
Universal gas constant
Coefficient in the equation of state of an ideal gas.
Unit: joule per mole kelvin ·
Lesson formulas
Basic MKT equation
Gas pressure is determined by the concentration, mass and average energy of particle motion.
Average particle energy via velocity
The average kinetic energy of a particle is determined by its mass and the mean square of its velocity.
Average particle energy via temperature
The average energy of translational motion of a monatomic particle is proportional to the absolute temperature.
Ideal gas pressure
Pressure is equal to the product of concentration, Boltzmann's constant and absolute temperature.
Relationship between temperature scales
The numerical value of temperature in Kelvin is approximately two hundred seventy-three greater than the value in Celsius.
Temperature range
A change in temperature of one kelvin is equal to a change of one degree Celsius.
RMS speed
The root mean square velocity of particles increases with temperature and decreases with molar mass.
Clapeyron-Mendeleev equation
The product of pressure and volume is determined by the amount of substance and temperature.
Equation of state through density
The pressure, molar mass, density and temperature of an ideal gas are related by one equation.
Gas density through particles
The density of a gas is equal to the mass times the volume and the product of the mass of the particle and the concentration.
United Gas Law
For a constant quantity of an ideal gas, the ratio of the product of pressure and volume to temperature is constant.
Boyle-Mariotte law
At constant temperature, the product of pressure and volume is constant.
Condition: The temperature and amount of gas are constant.
Charles's Law
At constant volume, the ratio of pressure to absolute temperature is constant.
Condition: The volume and quantity of gas are constant.
Gay-Lussac's Law
At constant pressure, the ratio of volume to absolute temperature is constant.
Condition: The pressure and quantity of gas are constant.
Boltzmann's constant
Boltzmann's constant relates temperature to the energy of an individual particle.
Universal gas constant
The universal gas constant relates the macroscopic parameters of an ideal gas.
Related formulas
The same formulas in the reference, with symbols and units.
Tasks on the topic
Statements, answer options and the walkthrough.