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I haven't totally gotten a grip back on how to compare reactants in order to determine which one is limiting, anyone have any tips? I understand we have to compare how many moles of each with respect to the equation, but I do not fully get how to reason through that.
Once you convert each of the reactants to moles, you can just choose one of the reactants and use the mole ratio from the balanced equation to find the amount of moles that are required of the other reactant. If the number of moles calculated of the second reactant is less than the amount given in the problem, that means it is excess, so the first reactant is limiting. If the number of moles calculated is greater than the amount given, then the second reactant is limiting because that means there is not enough of the second reactant to complete the reaction.
One trick I learned was to calculate the amount in moles of each reactant. Then, divide by that reactant's coefficient that is given in the balanced equation. The reactant with the lower ratio is the limiting reactant.
For determining limiting reactants the key is conceptualizing what is actually happening by looking at the coefficients. When a reaction has 2 reactants with coefficients of 1 and 2 for example and let's just say a single product with a coefficient of 2 what's really happening every time we run this hypothetical reaction is no different than a simple recipe for making bread. For a simple bread lets just say we take 1 cup of flour and 2 eggs and every time we run this reaction we end up with 2 loaves of breads; this is the same as what we're doing when we're finding the limiting reactant. We're determining in this example whether we would run out of eggs first or flour and whichever runs out first is our limiting reactant. So, in an actual problem given certain amounts of reactants the best thing to do first is convert everything to moles, then with each amount divide the amounts found by their respective coefficients and whichever number is the smallest is the limiting reactant.
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