Therefore, to calculate the molar mass of air, it is necessary to know the mass of the gas - m, the temperature - T, the gas pressure - P, and the volume it occupies. Complete gas removal from the vessel is almost impossible: even with the best modern engineering toolbox. There is another way of determining M, in which it is not necessary to achieve complete removal of the gas from the vessel - it is enough to change its mass slightly.
Let a vessel with volume V contain gas of mass m1 under pressure P1 and at temperature T. The equation of state for this gas will take the form:.
We pump out part of the gas from the vessel without changing its temperature. After evacuation, the mass of gas in the vessel and partial pressures will decrease. Let us denote them, respectively, m2, P2, and rewrite the equation of state:.
This expression allows you to determine - M. If the change in the mass of the gas, in pressure, the temperature, the volume is known. In this work, the investigated gas is air, known as a mixture of nitrogen, oxygen, carbon dioxide, argon, water vapor, and other gases.
The above formula is also suitable for determining the M mixture of gases. In this case, the found value of M is a certain average or effective molar mass of the gas mixture. The molar mass of a mixture of gases air , you can theoretically calculate. This method is suitable because the relative content and molar mass of each of the gases included in the mixture are known. The formula looks like this:.
You convert from "fraction" to "percent" by multiplying by The units of mass measurement used don't make a difference, as long as the top and bottom of the ratio use the same units: EXAMPLE: A stream contains 20 g of oxygen gas, 70 g of nitrogen, 5 g of helium, and 5 g of hydrogen.
Find the mass and mole fractions, mass and mole percent compositions. First, you need to find the mass of each component given , the total mass add them up.
You'll also need to calculate the moles of each component divide mass by molecular weight and the total moles. Now you have everything you need to calculate the composition fractions.
The fraction results can be checked by adding them up -- they must equal 1. Multiply the fractions by to get the percent composition. A concentration unit often seen in environmental usage is parts per million or ppm. It is the grams of solute in 1 million grams of solution.
PPM or ppb is a special kind of mass fraction. Aug 22, Explanation: This is a fun question. Hobbs table can be seen here on Google Books dry air is composed of: Nitrogen: Related questions How do you calculate the atomic mass of carbon? How are atomic mass and mass number different? How do you calculate atomic mass from isotopic composition? Cookies are only used in the browser to improve user experience.
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