N₂O (laughing gas) is used as an anesthetic. A dentist has a 2.00 L flask of N₂O at a pressure of 1.00 atm and a 3.00 L flask of nitrogen gas at 2.00 atm that are separated by a valve. What is the pressure in the flasks when the valve is opened, and the gases mix together? Both flasks are at the same temperature, and the temperature does not change when the gases mix.

Question

Quizplus · Accepted Answer

Before the valve is opened, the gases are at different pressures and occupy different volumes. However, since they are at the same temperature, we can use the ideal gas law to find the number of moles of each gas: n(N₂O) = (P × V)/(R × T) = (1.00 atm × 2.00 L)/(0.0821 L·atm/mol·K × 298 K) ≈ 0.096 mol n(N2) = (P × V)/(R × T) = (2.00 atm × 3.00 L)/(0.0821 L·atm/mol·K × 298 K) ≈ 0.145 mol When the valve is opened, the gases mix together and the total volume becomes 5.00 L. However, the total number of moles of gas remains constant. Therefore, we can use the total number of moles and the total volume to find the new pressure: n(total) = n(N₂O) + n(N2) ≈ 0.241 mol P(total) = (n(total) × R × T)/V(total) = (0.241 mol × 0.0821 L·atm/mol·K × 298 K)/5.00 L ≈ 1.60 atm Therefore, the pressure in the flasks when the valve is opened and the gases mix is 1.60 atm. The correct answer is C.

N2O (Laughing Gas) Is Used as an Anesthetic

N₂O (Laughing Gas) Is Used as an Anesthetic