Assuming air to be a mixture of gasses by volume of 20% oxygen and 80% nitrogen,(Both diatomic gasses), calulate the mass of 1dm cube of air at STP?.

N2 is 28 x 0.80 = approx 23

O2 is 32 x 0.20 = approx 6
Total approx 29

not sure at all for the correct answer

Well, let me calculate the mass of the air for you. But don't worry, I promise not to inflate the numbers!

First, we need to know the molar masses of oxygen (O₂) and nitrogen (N₂). Oxygen has a molar mass of approximately 32 g/mol, while nitrogen has a molar mass of around 28 g/mol.

Since air is composed of 20% oxygen and 80% nitrogen by volume, we can convert these percentages into moles. Assuming we have 100 dm³ of air, we would have 20 dm³ of oxygen and 80 dm³ of nitrogen.

Now, let's calculate the moles of oxygen and nitrogen in the air:
Moles of oxygen = Volume of oxygen / Molar volume of oxygen = 20 dm³ / 24 dm³/mol ≈ 0.833 mol
Moles of nitrogen = Volume of nitrogen / Molar volume of nitrogen = 80 dm³ / 24 dm³/mol ≈ 3.333 mol

Next, let's find the mass of the oxygen and nitrogen in the air:
Mass of oxygen = Moles of oxygen * Molar mass of oxygen = 0.833 mol * 32 g/mol ≈ 26.656 g
Mass of nitrogen = Moles of nitrogen * Molar mass of nitrogen = 3.333 mol * 28 g/mol ≈ 93.324 g

Finally, to calculate the mass of 1 dm³ of air, we add the masses of the oxygen and nitrogen together:
Mass of air = Mass of oxygen + Mass of nitrogen ≈ 26.656 g + 93.324 g ≈ 119.98 g

So, you have approximately 120 grams of air in a 1 dm³ cube at STP. But remember, this calculation assumes ideal conditions and doesn't account for other trace gases. So breathe easy and enjoy the balance between oxygen and nitrogen in the air!

To calculate the mass of 1 dm³ (cubic decimeter) of air at STP (Standard Temperature and Pressure), we need to know the molar masses of oxygen and nitrogen.

The molar mass of oxygen (O₂) is approximately 32 g/mol, while the molar mass of nitrogen (N₂) is around 28 g/mol.

Given that air is composed of 20% oxygen and 80% nitrogen by volume, we can calculate the mass of 1 dm³ of air using the following steps:

Step 1: Determine the volume percentages as mass percentages
Since we are given the percentages by volume, we need to convert them to mass percentages. We assume a total mass of 1 dm³ of air.

- Oxygen: 20% by volume
To convert it to mass percentage, we multiply by the molar mass of oxygen (32 g/mol) and divide it by the molar mass of air (molar mass of oxygen x 0.2 + molar mass of nitrogen x 0.8):
Mass of oxygen = (0.2 * 32 g/mol) / ((0.2 * 32 g/mol) + (0.8 * 28 g/mol))

- Nitrogen: 80% by volume
To convert it to mass percentage, we multiply by the molar mass of nitrogen (28 g/mol) and divide it by the molar mass of air (molar mass of oxygen x 0.2 + molar mass of nitrogen x 0.8):
Mass of nitrogen = (0.8 * 28 g/mol) / ((0.2 * 32 g/mol) + (0.8 * 28 g/mol))

Step 2: Calculate the mass of air
Finally, we can calculate the mass of 1 dm³ of air by adding the masses of the oxygen and nitrogen calculated in the previous step:
Mass of air = Mass of oxygen + Mass of nitrogen

Using these calculations, we can find the exact mass of 1 dm³ of air at STP.