A mixture of air and methanol vapour is fed to a converter in which the following reactions take place:

CH OH O HCHO H O 3 2 2 2 1 + ® + 3 2 CH OH ® HCHO + H

In addition, some methanol is completely oxidised to CO₂ and water. 25% of the methanol feed leaves the converter unreacted. After condensation of the unreacted methanol, formaldehyde (HCHO) and water vapour, the gas stream contains: 17% H2, 75% N₂ and 3% O₂ & 5% CO₂ by moles.

Calculate a) the ratio of air to methanol in the feed

b) the yield of formaldehyde from methanol (moles HCHO/mole CH₃OH feed)