So, gas compression by external force causes its, and expansion of gas is followed by its cooling. This phenomenon to a certain extent takes place always, but sharply I sweep up when the exchange of warmth with surrounding bodies is minimized because such exchange can compensate change of temperature to a greater or lesser extent.
Comparing the values received thus a and the volume of the air locked in a tube And, we will be convinced that at increase in volume of some mass of air in number of times its pressure in as much time, and vice versa. Air temperature in a tube at experiences can be considered invariable.
Usually change of pressure is caused by both reasons at once: both change of volume, and change of temperature. But it is possible to carry out the phenomenon so that at change of volume temperature will change is insignificant a little or at change of temperature volume practically remains invariable. We at first will also be engaged in these cases, having made previously still the following remark.
Increment of pressure of some mass of gas at a on 1 ° the which this mass of gas had at a temperature of 0 °C makes a certain part an of that. If to designate pressure at 0 °C through P, the gas pressure to.prirashcheniye when heating on 1 °C is ar.
Now we will slowly lift a tube of Century. We will see that mercury in both tubes will rise, but is not identical: in a tube In mercury level all the time will be higher, than in And. If to lower a tube In, mercury level in both knees goes down, but in a tube In decrease it is more, than in And.
Determination of density of gas can be carried out so. Let's weigh a flask with the crane twice: once having pumped out from it whenever possible completely air, having at times filled a flask with the studied gas up to the pressure which has to be known. Having divided a difference of scales into the flask volume which should be defined previously, we will find gas density under existing conditions. Then, using the equation a of gases, we will easily find gas density under normal conditions of dn. Really, we will put in a formula (1 P2 == Rn, V2=vn, T2=tn and, having increased numerator and a denominator
For definition of Cv it is necessary to heat the gas placed in the closed vessel. Expansion of the vessel when heating can be neglected. When determining Cp to heat the gas placed in the cylinder closed loading on which remains invariable.