A mixture of N2, O2, and CO2 has a total pressure of 928. torr. In this mixture the partial pressure of N2 is 31.0 cm Hg and the partial pressure of O2 is 4.00 dm Hg. What is the partial pressure of the CO2 (in torr)?
Ptotal = pN2 + pO2 + pCO2
You have only one unkinown; solve for that. However, note that the units are not the same. Since you want pCO2 in torr (mm Hg), I suggest you change the others to mm Hg.
To find the partial pressure of CO2 in torr, we need to calculate the moles of each gas in the mixture first.
1. Convert the given partial pressures to torr:
- Partial pressure of N2 = 31.0 cm Hg = 31.0 torr
- Partial pressure of O2 = 4.00 dm Hg = 4.00 * 10 torr = 40.0 torr
2. Use Dalton's Law of Partial Pressures to calculate the partial pressure of CO2:
- Dalton's Law states that the total pressure of a mixture of gases is equal to the sum of the partial pressures of the individual gases.
- Total pressure = partial pressure of N2 + partial pressure of O2 + partial pressure of CO2
Given:
- Total pressure of the mixture = 928 torr
- Partial pressure of N2 = 31.0 torr
- Partial pressure of O2 = 40.0 torr
To find the partial pressure of CO2:
- Partial pressure of CO2 = Total pressure - (Partial pressure of N2 + Partial pressure of O2)
- Partial pressure of CO2 = 928 torr - (31.0 torr + 40.0 torr)
Calculating:
- Partial pressure of CO2 = 928 torr - 71.0 torr
- Partial pressure of CO2 = 857 torr
Therefore, the partial pressure of CO2 in the mixture is 857 torr.