Percent Yield Example 1

Jules Bruno
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Here are example, Question says Consider the following balanced chemical reaction. So we have two moles of C six h six reacting with moles of oxygen gas to produce 12 moles of carbon dioxide gas, plus six moles of water as a liquid. It says. If a 2.6 g sample off see 686 reacted with excess oxygen to produce 1.25 g of water. What is the percent yield of water? All right, they want us to determine the percent yield. We know percent yield equals actual over theoretical times 100. If we read back on the question, they're telling me that I produced to 5 g of water. How can I determine if I produced something or made something made product? The only way I would know for sure is if I did the reaction in real life and obtain that amount. That 1.25 g represents our actual yield. So, really, what we have to do is calculate our theoretical yield. Remember, our theoretical yield can be determined by using store geometry, So if we look here, it says, step one map out the portion of the stoke geometric chart you will use well, excess, remember, Means we ignore. They're telling me that I have to 0.6 g of this reacted. That's the amount that gave to me. So that represents my grams off given. So the map that I'm gonna have to work out is grams of given Convert that into moles of given. Then I'm gonna have to convert. Those moles are given two moles of unknown. What's are unknown? Well, to figure out the units that I need, remember, your theoretical yield must have the same units as your actual yield. Our actual yield is in grams per of water, so we have to go all the way to grams of water. So we're gonna have here moles of unknown, which is water, and then finally end here in grams of unknown. Yeah. All right, so that's the story. Metric chart. At least a portion of it that we need to utilize to get our theoretical yield. All right, so we're gonna take the given quantity and change it into moles of given. We have to 6 g of benzene. We have six carbons and six hydrogen. When you look on the periodic table and take their atomic masses out of the six carbons out of the six hydrogen, you'll have a combined mass of 78.108 Gramps per one mole off. See 686 Next we're going to say here, Step three joy. Multiple comparison to convert moles of given into moles of unknown. To do that. Remember, we look at the coefficients of the balanced equation. We're gonna go for moles of C six h 62 moles of water and in our balance equation, it is a 2 to 6 ratio. Then it says, if necessary, convert the moles of unknown into desired units into the final design units. Since our actually yielded using grams of water are theoretical, yield needs to go to grams of water. One mole of water taken into account the two hydrogen and one oxygen. It has a combined mass of 18.16 g. Then if we multiply everything out and divide the what's on the bottom, we get 1.799 g of water. This year represents our theoretical yield. So plug that in tow. Our answer and then stop five We're already doing it. We're plugging in the actual yield and the theoretical yield, and that will help us to find our percent yield. So 1 to 1.25 divided by 1.799 times times 100 gives me 69.48% as my percent yield for this particular question. So just remember, parts of this are pretty familiar. They're incorporating things we've learned about stoke geometry and limiting re agents. And now just tacking on actual yield with that information were able to find our percent yield for this particular question.