Question

air consists of about 78.6% nitrogen, 20.9% oxygen, and 0.04% carbon dioxide. if we assume sea - level pressure of 760 mm hg, what is the ( p_{o_2} )?
multiple choice
159 mm hg
597 mm hg
3.7 mm hg
0.3 mm hg

Explanation:

Step1: Determine the formula for partial pressure

The partial pressure of a gas ($P_{gas}$) in a mixture is given by $P_{gas}=P_{total}\times \text{percentage of gas (in decimal)}$.

Step2: Convert the percentage of oxygen to decimal

The percentage of oxygen is $20.9\%$. To convert it to a decimal, we divide by $100$, so $20.9\%=\frac{20.9}{100} = 0.209$.

Step3: Calculate the partial pressure of oxygen ($P_{O_2}$)

We know that $P_{total}=760\space mm\space Hg$. Using the formula $P_{O_2}=P_{total}\times0.209$, we substitute the values: $P_{O_2}=760\times0.209$.

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Answer:

159 mm Hg