Air entering the lungs ends up in tiny sacs called alveoli. It is from the alveoli that oxygen diffuses into the blood. The average radius of the alveoli is \(0.0050 \mathrm{~cm}\) and the air inside contains 14 percent oxygen. Assuming that the pressure in the alveoli is 1.0 atm and the temperature is \(37^{\circ} \mathrm{C},\) calculate the number of oxygen molecules in one of the alveoli.

Short Answer

Expert verified
Provided that all calculations are done, the obtained number of oxygen molecules in one alveolus should be found by concluding step 4.

Step by step solution

01

Convert temperature to Kelvin

For calculations involving the ideal gas law, it is necessary to use temperatures in Kelvin. The Celsius-to-Kelvin conversion formula is \(K = C + 273.15\). Applying this conversion to our temperature, we find that the temperature in Kelvin is \(37^{\circ} \mathrm{C} + 273.15 = 310.15 \mathrm{K}\)
02

Calculate the volume of an alveoli

Alveoli have a spherical shape, so their volume can be calculated using the formula \( V = \frac{4}{3} \pi r^3 \), where r is the radius. Substituting the given radius \( r = 0.0050 \mathrm{~cm} = 0.000050 \mathrm{~m} \) , the volume of one alveolus becomes \( V = \frac{4}{3} \pi (0.000050^3) = 5.24 \times 10^{-10} \mathrm{~m^3}\)
03

Calculate the number of moles of oxygen in the alveolus

We know from the ideal gas law that \( n = \frac{PV}{RT} \), where P is the pressure (in this case 1.0 atm converted to N/m^2 is 101325 N/m^2), V the volume calculated in Step 2, T the temperature in K from step 1, and R the ideal gas constant (\( 8.314 N \cdot m / mol \cdot K\) ). Remember that the mole we find represents all the air in the alveolus, but we are only interested in the oxygen, which makes up 14% of this air. Thus, we need to multiply this result by 0.14 to find the moles of oxygen in an alveolus.
04

Calculate the number of molecules in a mole

We can find the number of molecules from the number of moles because 1 mole of any substance contains Avogadro's number of molecules ( approximately \(6.022 \times 10^{23}\) molecules). Therefore, multiplying the number of moles by Avogadro's number, we obtain the number of oxygen molecules in an alveolus.

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