Question

PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEASE HELP PLEWSE HELP PLEASE HELP ANYBODY!!! CHEMISTRY DUE IN 5 MINUTES!! DIMENSIONAL ANALYSIS
How many moles of O2 are in the sample of 3.6 kilograms of air if 21% of the air is oxygen, O2, by mass?

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Answer 1

Answer:

23.6 moles

Explanation:

From the question given above, the following data were obtained:

Mass of air = 3.6 Kg

Mass percentage of O₂ = 21%

Number of mole of O₂ =?

Next, we shall convert 3.6 Kg of air to grams (g). This can be obtained as follow:

1 kg = 1000 g

Therefore,

3.6 Kg = 3.6 Kg × 1000 / 1 kg

3.6 Kg = 3600 g

Next, we shall determine the mass of O₂ in the air. This can be obtained as follow:

Mass of air = 3600 g

Mass percentage of O₂ = 21%

Mass of O₂ =?

Mass of O₂ = 21% × 3600

Mass of O₂ = 21/100 × 3600

Mass of O₂ = 756 g

Finally, we shall determine the number of mole of O₂ in the sample of air. This can be obtained as follow:

Mass of O₂ = 756 g

Molar mass of O₂ = 2 × 16 = 32 g/mol

Number of mole of O₂ =?

Mole = mass /Molar mass

Number of mole of O₂ = 756 / 32

Number of mole of O₂ = 23.6 moles

Thus, the number of mole of O₂ in the

sample of air is 23.6 moles