The tunnel is 12 km long with a cross-section of 38 m2 and runs both ways for a total of 1000 cars per hour with an average petrol consumption of 12 dm3 /100 km. Petrol has an average density of 0. 75

The tunnel is 12 km long with a cross-section of 38 m2 and runs both ways for a total of 1000 cars per hour with an average petrol consumption of 12 dm3 /100 km. Petrol has an average density of 0. 75 kg/dm3 and contains 14% by weight. hydrogen. There is twice as much CO2 by volume in the exhaust gas as there is CO. The pressure in the tunnel is approx. 1 atm and a temperature of 290 K. Estimate the time after which, if the ventilation fails, the CO content of the tunnel will rise to the toxic limit of 0,8 ‰ vol.