Here in this example question, it says, how many grams of H₂O are produced when 12.3 grams of H₂ reacts? Alright. So we know that they're giving us information on one compound in a balanced equation and asking for information on another. We know that is the definition of stoichiometry. So we're going to have to utilize the stoichiometric chart in some way to solve this problem. Now, if we follow the steps, it says step 1, map out the portion of the stoichiometric chart you will use. From the question, they're giving us 12.3 grams of H₂. Since that's a value they're giving to you, that represents our grams of given. So we're going to start at grams of given, which is just grams of H₂, and we're going to convert those grams into moles of given, so moles of H₂. Now in the same question, they're asking us to find the grams of H₂O. Since we don't know they're asking us to find it. This represents our grams of unknown. So that tells me I have to go from moles of given and find a way to get to grams of unknown. Now at this point, to go from moles of given, I have to go to moles of unknown and that is where it's required to do the job. So we're going to go from moles of given to moles of unknown. And then finally, we go from moles of unknown to grams of unknown. This is the path that we're going to take to answer this question. So let's go to step 2. It says convert the given quantity into moles of given. And if a compound is set to be in excess, then just ignore it. In this question, they don't say anything as being in excess, so we don't have to worry about this, next line under step 2. Later on, we'll come into situations where we're told something is an excess. Excess, and in that case, we just simply ignore it. Alright. So we're going to take our given quantity, which is 12.3 grams H₂, and we're going to convert it into moles of given. Grams of H₂ go on the bottom, and 1 mole of H₂ goes on top. H₂ has in it 2 hydrogens, and according to the periodic table, each one weighs 1.008 grams, so that's 2.016 grams. Grams here cancel out and I'll have moles of H₂ which comes out to 6.1012 moles of H₂. So I've just gone from grams of H₂ to moles of H₂. At this point, we have to do the jump. So going to step 3, it says to do a mole to mole conversion in order to convert moles of given into moles of unknown. So we take that 6.1012 moles of H₂. To get rid of moles of H₂, I put them on the bottom. What am I looking for? I'm looking for my unknown. My unknown is water, so I need to find moles of H₂O. Now remember, to go from moles of given to moles of unknown, that's called the jump, and we do a mole-to-mole comparison. The equation says that for every 2 moles of H₂, I have 2 moles of H₂O. So for every 2 moles of H₂, I have 2 moles of H₂O. So here, moles of H₂ cancel out, and now I have moles of H₂O. So that's 6.1012 moles of H₂O. Now finally, if necessary, convert the moles of unknown into the final desired units. Sometimes they may ask us to just find the moles of our unknown, and in that case, we'd stop. For this particular question though, they're not asking us to find moles of water, they're asking us to find grams of water. So an additional step is required. So 6.1012 moles of H₂O. Gotta get rid of moles of H₂O, so one mole of H₂O on the bottom. How many grams of H₂O do we have on top? H₂O is composed of 2 hydrogens and one oxygen. Hydrogen, according to the periodic table, is 1.008 grams. Oxygen is 16 grams. This is 2.016 grams, and this is 16 grams, so the complete mass of H₂O is 18.016 grams. So we plug that here. Moles of water cancel out, and now I'm finally gonna have grams of water. So here we're going to multiply those out, so that's 109.9 grams of H₂O. Now technically within this question, 12.3 has 3 significant figures. So technically we should write this in 3 significant figures as well. So in scientific notation that will come out to 1.10 × 10² grams of H₂O. So this would be our final answer for this stoichiometric question. So remember, if we are given the amount of a compound within a balanced equation and asked to find another, we're dealing with stoichiometry, which means you have to utilize the stoichiometric chart in order to find your final answer.