Q. 8.70 - An Introduction to General, Organic, and Biological Chemistry

Question

An airplane is pressurized with air to $650 mmHg$.$(8.7)$

a. If air is $21\%$ oxygen, what is the partial pressure of oxygen on the plane?

b. If the partial pressure of oxygen drops below $100 mmHg$. passengers become drowsy. If this happens, oxygen masks are released. What is the total cabin pressure at which oxygen masks are dropped?

Step-by-Step Solution

Answer

a. On the plane, the partial pressure of oxygens is $136.5 mmHg$.

b. The total cabin pressure when oxygen masks are dropped is $476.2 mmHg$.

Part (a) step 1: Given Information

We need to find the partial pressure of oxygen on the plane.

Part (a) step 2: Simplify

Here,

Total pressure $P_{total}=650 mmHg$ 

 the total pressure is the sum of all partial pressures.

$21\%$ oxygen, it means partial pressure of oxygen $=21\%\left(P_{total}\right)$

$=\left(\frac{21}{100}\right)\times 650=136.5 mmHg$

Part (b) step 1: Given Information

We need to find the total cabin pressure at which oxygen masks are dropped.

Part (b) step 2: Simplify

Now, finding the total pressure $P_{total}$:

 the total pressure is the sum of all partial pressures.

$21\%$ oxygen means partial pressure of oxygen $=21\% \left(P_{total}\right)$

$P_{total}=\left(\frac{100}{21}\right)\times 100 mmHg=476.2 mmHg$