What is the molecular weight of air?

Answer 1

28.96 g / mol

What a fun question this is.

Dry air is made up of the following, per table 5.1 on page 155 of Atmospheric Science: An Introductory Survey by John M. Wallace, Peter V. Hobbs (table viewable here on Google Books):

78.084% nitrogen, 20.946% oxygen, 0.934% argon, and 0.03% carbon dioxide

These add up to 78.084 + 20.946 + 0.934 + 0.03 = 99.994% (trace amounts of other gases make up the remaining material, 100 - 99.994 = 0.006%).

One mole of gas at standard temperature and pressure takes up 22.4 liters, so these percentages are percentage volume. However, since the volumes cancel out, that is really unrelated to the question at hand.

The weights of atoms and molecules are:

Remember that nitrogen is 14.0067 x 2 = 28.0134 g/mol, oxygen is 15.9994 x 2 = 31.9988 g/mol, argon is 39.948 g/mol, and carbon dioxide is 44.01 g/mol.

Since we are aware of the composition percentage, we can use that information to determine each component's weight:

Argon: (0.934 / 100) x 39.948 = 0.373 g/mol; Carbon dioxide: (0.03 / 100) x 44.01 = 0.013203 g/mol; Nitrogen: (78.084 / 100) x 28.0134 = 21.8739 g/mol; Oxygen: (20.946 / 100) x 31.9988 = 6.7025 g/mol

These equal 21.8739 + 6.7025 + 0.373 + 0.013203 = 28.96 g/mol when added together.

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Answer 2

The molecular weight of air, which is a mixture of gases primarily composed of nitrogen (N2) and oxygen (O2), is approximately 28.97 grams per mole (g/mol).

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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