Chemistry

# What is the mole fraction of oxygen gas in air?

234 ###### 2014-11-20 18:48:23

The mole fraction of Oxygen = 21/100= .21

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## Related Questions You need to distinguish between oxygen gas and atmospheric oxygen. Oxygen gas is 16 grams per mole, while atmospheric oxygen (O2) has twice the amount of oxygen and, therefore, weighs 32 grams. The chemical equation for hydrogen gas and oxygen gas combining to form water is as follows: 2H2 (g) + O2 (g) ---&gt; 2H2O (l). This means that for every 1 mole of oxygen gas reacting, two moles of hydrogen gas are needed. So if 0.50 moles of oxygen gas react to form one mole of water, then one mole of hydrogen gas was used. There are always ONE mole of gas in 22,4 L gas of any kind (even gaseous mixtures like air) at stp.So 68.5 (L) / 22.4 (L/mole) = 3.06 mole gas in 68.5 L (at STP) 3.120 grams oxygen gas (1 mole O2/32 grams)(6.022 X 1023/1 mole O2) = 5.871 X 1022 atoms of oxygen gas ------------------------------------------------ 38 grams oxygen gas (1 mole O2/32 grams)(6.022 X 1023/1 mole O2) = 7.2 X 1023 molecules of oxygen gas ------------------------------------------------- Like a pressure, but with non-ideality Use as a pressure Fugacity = mole fraction of gas * total pressure Mole fraction of CO2 in atmosphere? 383 ppmv find the mole fraction on each: Mole fraction gas (X) = moles of gas (X) / total moles of all gases Then use this formula: Pi = X Pt Where Pi = partial pressure of gas i X = mole fraction of gas i Pt = total pressure of all gases How do you calculate the total pressure?Is it just the total number of moles?Or do you need to convert it to Pascals? Oxygen: 32 g/mole O2 Carbondioxide : 44 g/mole CO2 ( = 12 + 32) One mole of each (= any) gas has the same volume, 22.4 L (at Standard T and p) 16 grams or 32 grams, depending on what you're looking at.The mass of one mole of oxygen atoms is about 16 grams, but oxygen gas exists as a molecule (O2) so 1 mole of (O2) is 32 grams. Oxygen gas is composed of diatomic O2 molecules. From the periodic table, the atomic weight indicates that the molar mass of oxygen atoms is 16.0g/mole. The diatomic molecule O2 has twice the molar mass as oxygen atoms, and its molar mass is 32g/mole. For any gas, at most temperatures and pressures, the number of particles in a given volume is the same (based on the Ideal Gas Law -- see the Related Questions to the left for more information). The density is defined as the mass divided by volume, and therefore the density of a gas depends only on the mass of the particles. Since molecular oxygen is heavier than the average weight of air, which is largely composed of molecular nitrogen (which is lighter) and molecular oxygen, then oxygen is denser than air.Based on the composition of air (see the Related Questions to the left), the average molecular weight of air is 28.97 grams per mole (which is dominated by the molecular weight of N2, which is 28.0134 g/mole because the atmosphere is nearly 80% N2). The molecular weight of oxygen, O2, is 32.0 grams per mole which is just slightly heavier. Therefore, oxygen is just slightly more dense than air, but not by much. In comparison, the molecular weight of helium, He, is only 4.003 g/mole, which is much lighter than air!~air is made up of nitrogen, oxygen, argon, and carbon dioxide The volume of one mole of oxygen can be estimated by the ideal gas law. In this case, you will use V = nRT/P, where n is the moles of gas, R is the ideal gas constant, T is the temperature in kelvin, P is the system pressure.

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