A breathing mixture used by deep-sea divers contains helium, oxygen, and carbon dioxide What is the partial pressure of oxygen at $101.4$ $kPa$ if $P_(He)$ = $82.5$ $kPa$ and $P_(CO2)$ = $.4$ $kPa$ ?

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Answer 1 · 2016-02-22T01:43:51

The partial pressure of oxygen in the mixture is 18.5 kPa.

The total pressure is the sum of the partial pressures of the given gases.

$P_"Total"=P_"He"+P_"CO2"+P_"O2"$

Rearrange the equation to isolate $P_"O2"$ , substitute the given values into the equation and solve.

$P_"O2"=P_"Total"-(P_"He"+P_"CO2")$

$P_"O2"=101.4"kPa"+(82.5"kPa"+0.4"kPa")$

$P_"O2"=18.5"kPa"$

Answer 2 · 2016-02-22T01:45:29

The total pressure of $101.4$ $kPa$ is made up of the sum of the partial pressures of the three gases, so $P_(O2)=101.4-82.5-0.4=18.5$ $kPa$ .

In a little more detail, the total pressure is the sum of the partial pressures of the gases present:

$P_("tot")=P_(O2)+P_(He)+P_(CO2)$

We want to know the partial pressure of oxygen, $P_(O2)$ , so we rearrange:

$P_(O2)=P_("tot")-P_(He)-P_(CO2)$

Substituting in the known values gives the answer shown above.

A breathing mixture used by deep-sea divers contains helium, oxygen, and carbon dioxide What is the partial pressure of oxygen at 101.4101.4 kPakPa if P_(He)P_(He) = 82.582.5 kPakPa and P_(CO2)P_(CO2) = .4.4 kPakPa?