# A mixture of "N"_2, "O"_2. and "CO"_2 has a total pressure of "740 torr" In this mixture, the partial pressure of "N"_2 is "120 torr" and the partial pressure of "O"_2 is "400 torr". What is the partial pressure of "CO"_2 ?

Feb 24, 2018

$\text{220 torr}$

#### Explanation:

From Dalton's Law of Partial Pressures, the total pressure of a mixture of gases is the sum of the partial pressures of each gas.

Therefore, the partial pressure of ${\text{CO}}_{2}$ is

$\text{740 torr " - " 120 torr " - " 400 torr = 220 torr}$

Feb 24, 2018

$220 \text{torr}$

#### Explanation:

According to Dalton's Law of Partial Pressures,

${P}_{\text{total}} = \Sigma {P}_{i}$, or ${P}_{\text{total}} = {P}_{1} + {P}_{2} + \ldots . {P}_{n}$

Here, we can write the above as:

${P}_{\text{total}} = {P}_{{N}_{2}} + {P}_{C {O}_{2}} + {P}_{{O}_{2}}$

Here,

${P}_{\text{total"=740"torr}}$

${P}_{{N}_{2}} = 120 \text{torr}$

${P}_{{O}_{2}} = 400 \text{torr}$

Inputting, we get:

$740 = 120 + 400 + {P}_{C {O}_{2}}$

$740 = 520 + {P}_{C {O}_{2}}$

${P}_{C {O}_{2}} = 220 \text{torr}$