For the solution of some physical tasks happens it is necessary to count gas pressure. At the same time both air and vapors of substance, and gas which is in a vessel can be mentioned in a task. How exactly to calculate gas pressure, depends on what parameters are set in a task.
It is required to you
- - formulas for calculation of pressure of gas.
Instruction
1. Find pressure of ideal gas with values of average velocity of the molecules, mass of one molecule and concentration of substance on formula P=⅓nm0v2 where n is concentration (in grams or moths on liter), m0 is the mass of one molecule.
2. If in a condition density of gas and average speed of its molecules is given, calculate pressure by formula P=⅓ρv2 where ρ — density in kg/m3.
3. Calculate pressure if you know temperature of gas and its concentration, using a formula P=nkT where k is Boltzmann's constant (mol k=1.38·10-23 · K-1), T — temperature on an absolute scale of Calvin.
4. Find pressure from two equivalent options of the equation of Mendeleyev-Clapeyron depending on the known values: P=mRT/MV or P=νRT/V where R is a universal gas constant (J/mol R=8.31 · J), ν — amount of substance in moths, V – gas volume in m3.
5. If in a statement of the problem the average kinetic energy of molecules of gas and its concentration is specified, find pressure by means of a formula P=⅔nEк where Ek is kinetic energy in J.
6. Find pressure from gas laws — isochoric (V=const) and isothermal (T=const) if pressure in one of states is given. At isochoric process the relation of pressure is equal in two states to the relation of temperatures: P1/P2=T1/T2. In the second case if temperature remains a constant, the work of pressure of gas upon its volume in the first state is equal to the same work in the second state: P1·V1=P2·V2. Express unknown size.
7. Calculate pressure from a formula of internal energy of ideal one-atomic gas: U=3·P·V/2 where U – internal energy in J. Otsyud pressure will equal: P=⅔\· U/V.
8. When calculating partial vapor pressure in air if in a condition temperature and relative air humidity are given, express pressure from a formula φ/100= to P1/P2 where φ/100 — relative humidity, P1 — the partial pressure of water vapor, P2 — the maximum value of vapors of water at this temperature. During calculation use tables of dependence of the maximum elasticity of steam (maximum partial pressure) on temperature in degrees Celsius.