Help! I’m having a really hard time in Chemistry right now and my teacher is going way too fast. I’m unable to retain nearly all of the rules for Stoichiometry dimensional analysis. Is there an easier way to remember this? Thank you!
In: Chemistry
Stoichiometry is making sure that each reaction is balanced on both sides. So if you were burning natural gas (methane, CH*_4_*) with oxygen (O*_2_*), you would need to burn one molecule of methane with two molecules of oxygen:
CH*_4_* + 2O*_2_* -> CO*_2_* + 2H*_2_*O
You must have the same number of atoms of each element coming into the reaction as leaving the reaction.
Dimensional analysis is a way of looking at the units of a reaction/process to make sure that you are properly converting them around. If 1000 g is equal to 1 kg, then you can write a fraction using the two units: (1 kg)/(1000 g), or (1000 g)/(1 kg). Then you can multiply any number by this fraction in order to convert the units and account for the conversion factor. The fraction itself doesn’t chance the value of the original number, since the numerator and denominator are equal: X/X = 1, and you can multiply anything by 1 without changing it.
So if you were trying to find the weight in pounds of 330 mL of gasoline, you could multiply the volume (330 mL) by the density of gasoline (0.755 g)/(1 mL) by the conversion factor between pounds and grams (1 lb)/(453.59 g). If you multiply/divide that all out correctly, you get 330 * 0.755 / 453.59 = 0.549 lb, about half a pound of gasoline.
Latest Answers