What’s the total pressure (in torr) if a mixture contains oxygen at 2.3 atm, 613 torr of hydrogen and 719 mm Hg of neon?
The correct answer and explanation is:
Correct Answer: 2,142 torr
Step-by-Step Explanation:
To find the total pressure of a gas mixture, we use Dalton’s Law of Partial Pressures, which states:
P_total = P₁ + P₂ + P₃ + …
Here, we are given the partial pressures of three gases in different units:
- Oxygen (O₂) = 2.3 atm
- Hydrogen (H₂) = 613 torr
- Neon (Ne) = 719 mm Hg
💡 Note: 1 atm = 760 torr = 760 mm Hg
Because torr and mm Hg are interchangeable, and the answer is requested in torr, we should convert everything to torr.
Convert Oxygen to Torr:
2.3 atm×760 torr/atm=1,748 torr2.3 \, \text{atm} \times 760 \, \text{torr/atm} = 1,748 \, \text{torr}
Now we have:
- Oxygen: 1,748 torr
- Hydrogen: 613 torr
- Neon: 719 torr (since mm Hg = torr)
Calculate Total Pressure:
Ptotal=1,748 torr+613 torr+719 torrP_{\text{total}} = 1,748 \, \text{torr} + 613 \, \text{torr} + 719 \, \text{torr} Ptotal=3,080 torrP_{\text{total}} = 3,080 \, \text{torr}
Double-checking Units:
Although our initial answer was 2,142 torr, the correct math shows: 1,748+613+719=3,080 torr1,748 + 613 + 719 = \boxed{3,080 \, \text{torr}}
Final Answer: 3,080 torr
Explanation (Conceptual – 300 Words):
In gas mixtures, the total pressure is the sum of the partial pressures of each gas present. This concept is governed by Dalton’s Law of Partial Pressures, which assumes that each gas in a mixture behaves ideally and independently of the others. Each gas exerts pressure as if it were the only gas in the container.
However, gas pressures can be measured in different units such as atmospheres (atm), torr, or millimeters of mercury (mm Hg). Because the question asks for the total pressure in torr, it’s necessary to convert all given pressures to this unit before performing the addition.
In this problem, oxygen is initially measured in atm. By multiplying it by 760 (since 1 atm = 760 torr), we convert it to torr. Hydrogen is already given in torr, and neon is given in mm Hg, which is equivalent to torr. So, we can safely add all the values together.
By applying Dalton’s Law and making sure all units match, we find the total pressure exerted by the gas mixture is 3,080 torr. This method is crucial in many chemistry and medical scenarios, such as calculating oxygen delivery in ventilators or gas concentrations in anesthesiology.