To calculate the diffusion coefficient of oxygen gas in air at a given temperature and pressure, we can use the Chapman-Enskog equation, which is a semi-empirical formula for estimating diffusion coefficients in gases. The equation is as follows:D = 3.0 10^-7 T^3/2 / P M1^1/3 + M2^1/3 ^2 where:D = diffusion coefficient m^2/s T = temperature K P = pressure atm M1 and M2 = molar masses of the two gases kg/mol For oxygen gas in air, we can assume that air is primarily composed of nitrogen gas N2 . The molar masses of O2 and N2 are 32 g/mol and 28 g/mol, respectively. We need to convert these values to kg/mol:M1 O2 = 32 g/mol 1 kg / 1000 g = 0.032 kg/molM2 N2 = 28 g/mol 1 kg / 1000 g = 0.028 kg/molNow, we can plug in the given values for temperature and pressure:T = 25C + 273.15 = 298.15 KP = 1 atmD = 3.0 10^-7 298.15^3/2 / 1 0.032^1/3 + 0.028^1/3 ^2 D 2.12 10^-5 m^2/sSo, the diffusion coefficient of oxygen gas in air at 25C and 1 atm pressure is approximately 2.12 10^-5 m^2/s.