Instruction

1

Gas, whatever its composition, has three main parameters: mass, volume and density. Most tasks operate on the so-called ideal gas, so they must rely only on those given in the values of mass, pressure, temperature. For example, in the problem statement can be specified nitrogen gas N2 with a temperature of 60 degrees, a pressure of 30 kPa and a mass of 0.05 g. Knowing these three parameters and the composition of the gas, by the equation Mendeleev-Clapeyron possible to find its volume. It is necessary to adapt the equation as follows:

pV=mRT/M.

By further transformation formulas, find the volume of nitrogen:

V =mRT/pM.

In this case the molar mass M can be found in the table of D. I. Mendeleev. The nitrogen in it is equal to 12 g/mol. Then:

V=0,05*12*8,31*333/30*12≈4,61.

pV=mRT/M.

By further transformation formulas, find the volume of nitrogen:

V =mRT/pM.

In this case the molar mass M can be found in the table of D. I. Mendeleev. The nitrogen in it is equal to 12 g/mol. Then:

V=0,05*12*8,31*333/30*12≈4,61.

2

If a known volume under normal conditions, and the amount under other conditions is required, apply the laws of Boyle and Gay-Lussac:

pV/T=pнVн/T.

In this case, the transform formula is as follows:

pV*T=pнVн*T.

Hence the volume V is equal to:

V=pнVн*T/p*T.

The index n means the value of a parameter under normal conditions.

pV/T=pнVн/T.

In this case, the transform formula is as follows:

pV*T=pнVн*T.

Hence the volume V is equal to:

V=pнVн*T/p*T.

The index n means the value of a parameter under normal conditions.

3

If we consider the volume of gas from the point of view of thermodynamics, it is possible to notice that gases can act forces by which changing the volume. The gas pressure constantly, which is typical for Isobaric processes. In such a process the volume changes from one value to another. They may be designated as V1 and V2. In terms of the number of tasks describes some gas under the piston in the vessel. During the expansion of the gas piston moves a distance dl, with the result that the work is carried out:

A=pdV=p(V2 -V1).

This formula relates the change of the gas volume and work. As you know, if given final volume V2, it is possible to find the initial volume V1:

V1=pV2-A/p.

A=pdV=p(V2 -V1).

This formula relates the change of the gas volume and work. As you know, if given final volume V2, it is possible to find the initial volume V1:

V1=pV2-A/p.

4

Finally, the easiest way to find the volume of gas on the basis of two different physical parameters - mass and density. If the conditions specified gas with a certain density and mass, its volume should be calculated according to the formula:

V=m/ρ.

Each gas has a specific density, as well as any solid or liquid substance. Therefore, finding the volume of gas in the first place it is necessary to consider this option.

V=m/ρ.

Each gas has a specific density, as well as any solid or liquid substance. Therefore, finding the volume of gas in the first place it is necessary to consider this option.

# Advice 2: How to find a job gas

The working

**gas**is carried out while changing the volume. That is when the quantity**of gas**moves the nodes of the heat engine, whether internal combustion engine or a bullet in the barrel of the gun. In various processes**of gas**is calculated differently.You will need

- - pressure gauge;
- thermometer.

Instruction

1

If the working

**gas**is carried out in the Isobaric process (at constant pressure), in order to find the**working****gas**using a manometer, measure the pressure**of gas**. Then measure its volume before executing the operation and after. Find the change in volume**of gas**, subtracting from the final value to the initial one. Then find the product of the pressure**of the gas**to change its volume. This will be the work**gas**at constant pressure A=p•ΔV.2

For a perfect

**gas**to calculate**work**at a constant pressure by applying the equation of Clapeyron-Mendeleev. Find**a job****gas**by multiplying its mass by the number 8,31 (universal gas constant) and the temperature change in operation. The result, divide by the molar mass**of gas**A=m•R•T/M. in the calculations note that if the work is done by the gas (it expands), then it is positive. If the work is performed on the gas (it is held by outside forces), then the work is negative.3

If the work is done by the isothermal expansion (when temperature is constant), find the change in the volume of

**gas**and its temperature. To find**the work****gas**, multiply its mass by the number 8,31 (universal gas constant) and the temperature in carrying out the work. The result, divide by the molar mass**of the gas**. The number you multiply by the natural logarithm of the ratio of final and initial volumes**of gas**A=m•R•T•ln(V2/V1)/M.4

In General, to find

**work****gas**take the integral of a function of pressure by volume. The boundaries of the integral from the initial to the final volume ∫pdV. If there is a schedule of the process gas in the coordinates (V,p), as a rule, it is a straight line, find the area of a trapezium bounded laterally by lines perpendicular to the axis of V the points V1 and V2, bottom axis V, and the top graph of the function. In more complex cases, searched the area of the curvilinear trapezoid.Useful advice

If volume of gas does not change, the work is not performed.