A compressed gas cylinder of H2 containing 25 l at 200,000 kPa of pressure is emptied due a leak in a gas chromatography laboratory, with the following dimensions: 5 m long, 4 meters wide and 2.5 m height. Calculate the % oxygen and hydrogen in the atmosphere of the laboratory after the leak. If the lower explosive limit (LEL) of H2 is 4%, is there a risk of explosion?

Question

A compressed gas cylinder of H2 containing 25 l at 200,000 kPa of pressure is emptied due a leak in a gas chromatography laboratory, with the following dimensions: 5 m long, 4 meters wide and 2.5 m height. Calculate the % oxygen and hydrogen in the atmosphere of the laboratory after the leak. If the lower explosive limit (LEL) of H2 is 4%, is there a risk of explosion? 
Taking into account the apparent volume of gas once expanded.