Asample of h2 gas (2.0 l) at 3.5 atm was combined with 1.5 l of n2 gas at 2.6 atm pressure at a constant temperature of 25 °c into a 7.0 l flask. the total pressure in the flask is atm. assume the initial pressure in the flask was 0.00 atm and the temperature upon mixing was 25 °
c.

For this system, we use Dalton's law of partial pressures where the total pressure of a gas mixture is said to be equal to the sum of the partial pressures of the gases. The partial pressure of each gas would be calculated by the product of the mole fraction and the original pressure of the gas. We do as follows:

Total pressure = x1P1 + x2P2
Total pressure = (2.0 / 7.0 )(3.5) + (1.5/7.0)(2.6)
Total pressure = 1.56 atm