Uncle Sherm wrote:MarcusAurelius wrote:practice moar
did you get a schaum's outline for your courses?
I will now. I wanted to wait and see how useful the books were before I spent any more. Definitely need one for the Chem class. This is general chemistry for engineers, but the professor thinks we should be able to work out how much of something is produced in a reaction, even if he doesn't provide the entire equation for us to balance (for example, the last quiz question was "burning 3 moles of butane creates 1.5 moles of CO2, so what is the % yield of CO2?"). Basically If you aren't able to do this in 10 minutes or less, you don't pass the class. To do that problem, you have to know that Butane burns with Oxygen, and in addition to CO2, it produces H2O. Then you can balance the equation, and then do the stoichiometry, and then figure the % yield. That was the first of two questions on a pop quiz 3 weeks into class. We had 20 minutes to answer both questions.
the combustion of hydrocarbons represent a standard reaction- should be in the first few chapters of your textbook. one of the handful you should generally know for gen chem (which is more about concepts than memorization - nomenclature aside).
CxHy + (x+[y/4])O2 -> xCO2 + (y/2) H2O
if you want to save some time manually balancing that reaction, use the coefficient relationships above. might have to multiply all the coefficients by 2 if you end up with something that ends in 0.5 (when the number of hydrogens in your hydrocarbon is odd, for example).