Stoichiometry help #8

Question

Methanol, CH₃OH, is an important industrial compound that is produced from the following (unbalanced) reaction.

CO(g) + H₂(g) —> CH₃OH(g)

What mass of each reactant would be needed to produce 725.0 kg of methanol?

CO

__ g

H₂

__ g

Answer 1

First balance the equation:

CO +2H₂ -> CH₃OH

Now we need to recognize the relationships in this reaction equation. How are these compounds related? Mols? Mass? Reactions represent mols of compounds used and produced. So before we can even start, we have to get our given information into mols. For ease of calculation, I will be using kilomols, kmols.

75kg CH₃OH / 32 kg/kmol = 22.66 kmols of CH₃OH

To calculate how much is consumed we need to figure out how many mols are needed for each reagent.

CO:

1 kmol CO/1 kmol CH₃OH * 22.66 kmol CH₃OH = 22.66 kmol CO needed

H₂:

2 kmol H₂/1 kmol CH₃OH * 22.66 kmol CH₃OH = 45.32 kmol H₂ needed

Now we simply use the molar mass of each compound to determine the mass needed.

CO:

22.66 kmol CO * 28 kg CO/kmol CO = 634.38 kg CO

H₂:

45.32 kmol H₂ * 2 kg H₂ / kmol H₂ = 90.64 kg H₂