Mixtures of helium and oxygen are used in scuba diving tanks to help prevent "the bends". For a particular dive, 27.7 L of oxygen gas at 25.0°C and 1.51 atm, and 7.54 L of helium gas at 25.0°C and 2.97 atm were pumped into a tank with a volume of 6.00 L at 25.0°C. Calculate (in atm): 1. the partial pressure of oxygen 2. the partial pressure of helium 3. the total pressure in the tank at 25.0°C. A cylinder of compressed gas rolls off a boat and falls to the bottom of a lake. Eventually it rusts and the gas bubbles to the surface. A chemist collects a sample of the gas with the idea of trying to identify the gas. The wet gas collected occupies a volume of 275 mL at a pressure of 711 torr and temperature of 28.0°C. The vapor pressure of water at 28.0°C is 0.0372 atm. 1. Calculate the volume (L) that the gas occupies after it is dried (the water vapor removed) and stored at STP. 294.82L The phrase "wet gas" indicates that water vapor is also present in the sample. Remember to take the vapor pressure of water into account by subtracting it from the total pressure given in the problem. Treat this as a two condition problem, that is, use: P1V1/n1T1 = P2V2/n2T2 Notice that the moles of gas are constant between the wet and dry samples (n1=n2). Next, rearrange and simplify the two condition equation to solve for the volume of the dry gas (V2). (STP conditions are 760 torr, 273 K and 1 atm = 760 torr) Submit Answer Incorrect. Tries 1/99 Previous Tries The mass of the dry gas is 202 mg. A fragment of the tank indicates that the gas is a monoatomic element. 2. Write out the full name of the gas.