1. The problem statement, all variables and given/known data I was doing a gas law stoichiometry problem - https://scontent-b-mia.xx.fbcdn.net/hphotos-prn2/v/1395119_10201040722401960_650319510_n.jpg?oh=e9741ad3f8f73c8bda9bf689ae17e5a8&oe=52834E47 2. Relevant equations Pressure is proportional to the number of moles. We can convert pressure to moles. 2.4 moles of CO and 4.5 moles of O2 react to form CO2. The balanced equation is 2CO + O2 --> 2CO2. 3. The attempt at a solution The limiting reactant is oxygen. With 4.5 moles of oxygen only 2.25 moles of carbon dioxide can be formed. Even though oxygen is a limiting reactant, this does not imply that oxygen is completely consumed, correct? I somehow had the misconception that limiting reactants were completely consumed, so I incorrectly calculated the final pressure as the pressure of the carbon dioxide generated (2.25 atm) added to the pressure of whatever carbon monoxide remained (0.15 atm, since 2.25 moles of CO was used). I thought of an analogy - imagine a car. There must be a certain ratio of fuel and oxygen. Fuel is the limiting reactant in a flooded engine. THERE IS STILL FUEL. Although fuel is limiting, it doesn't mean there is 0 fuel. There simply way too much oxygen for the fuel to combust. (ETA: I googled flooded engines and I'm still not completely clear on which is in excess but either way, it's clear that one component - either fuel or oxygen - is preventing a car from starting up; that one component is limiting, but neither is 0. Not a car mechanic here!) So ... two things really. Is my work and reasoning correct? Also, where may this misconception that the limiting reactant is completely spent have come from? ---- ETA: googling "limiting reactant completely consumed" (https://www.google.com/search?q=lim...limiting+reactant+completely+consumed&spell=1) seems to yield reinforcements of my misconception: So ... is the LR completely consumed?