Ideal consider gas in which interaction between molecules is negligible. Besides pressure, the condition of gas is characterized by temperature and volume. Ratios between these parameters are displayed in gas laws.
Instruction
1. Gas pressure in direct ratio to its temperature, amount of substance, and in inverse proportion to the volume of the vessel occupied by gas. As coefficient of proportionality serves the universal gas constant R approximately equal 8.314. It is measured in the joules divided into mol and into kelvin.
2. This situation forms mathematical dependence of P=νRT/V where ν – amount of substance (mol), by R=8.314 – a universal gas constant (J/mol • J), T is gas temperature, V – volume. Pressure is expressed in pascals. It can be expressed also in the atmospheres, at the same time to 1 atm = 101.325 kPa.
3. The considered dependence – consequence from Mendeleyev-Klapeyrona's equation (PV=m/M) • RT. Here m is the mass of gas (g), M – its molar weight (g/mol), and the fraction of m/M gives as a result amount of substance ν, or number of moles. Mendeleyev-Klapeyrona's equation is fair for all gases which are admissible to be considered ideal. It is the fundamental physical and chemical gas law.
4. Watching behavior of ideal gas, speak about so-called normal conditions – environmental conditions with most of which often it is necessary to deal in fact. So, normal conditions (N at.) assume temperature in 0 degrees Celsius (or 273.15 degrees on Calvin's scale) and pressure in 101.325 kPa (1 atm). The value what the volume of one is equal to asking ideal gas under such circumstances is found: L/mol Vm=22.413. This volume is called molar. Molar volume – one of the main chemical constants applied in the solution of tasks.
5. It is important to understand that with a constant pressure and temperature the gas volume also does not change. This remarkable postulate is formulated in the law of Avogadro who claims that the volume of gas is directly proportional to number of moths.