Answer:
since you only need 11 grams of propane to produce 36 grams of water you can divide 273.6 by 36. This gives us 7.6 which would be our "unit rate". We can then multiply 7.6 by 11 grams, which gives us 83.6.
So the answer is 83.6 moles of propane.
I hope this answers your question(s). Have a good weekend!
