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Problem 127

Citric acid (right) is concentrated in citrus fru…

04:07
University of Maine
Problem 126
Answer

$\mathrm{m}\left(\mathrm{SiF}_{4}\right)=3,4 \mathrm{g}$


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Video Transcript

given a picture of a chemical reaction, we can write a balanced equation based on what the reactant and products are. So if we look at this picture and we see that the gray represents silicon and the blue is hydrogen, this is a molecule of S I h four. The purple is nitrogen and there are two together combined with four florins which are green. These react to make a new compound with silicon in it with the four Florence plus nitrogen and two and hydrogen. And so then we can balance it, noticing that everything is balanced except for the hydrogen. So we needed to hear. So this is the balanced equation. If each little molecule represents 1.25 moles of reacted 1.25 times 10 to the minus two moles there are three of them. That means we're starting with 3.75 times 10 to the minus. Two moles of S I age for you see the same for the other reactor. If each molecule represents 1.25 moles but there are three of them in the picture. We're starting off with 3.75 times 10 to the minus two No rules, the other reactant and to ask for. And so the question is, how much of this product should be formed or the theoretical yield? So because we have reacted quantities of both reactions, the limiting re agent problems. So we start off moles of reactant, which we can then find our mole of product using the coefficients from the balanced equation seven grams using the molar mass, we'll use our balanced equation and molar mass. Whichever reactant produces the smaller quantity of product is the amount that's produced and we call that are theoretical yield. So 3.75 times 10 to the minus two moles s I H four balanced equation tells me that I should produce one mole S I F. Four for every one mole of S I H four where I should produce the same amount of moles. I find the Moeller math by adding up mass of silicon plus four florins, mrs 104 0.77 grams for every more, or I'll produce 3.90 grams using the other quantity of reacted. We should see that we'll get the same amount product because the ratio is again a 1 to 1 ratio. So in this case, there's no limiting re agent, and the theoretical yield is 3.90 grams of silicon tetra fluoride. Our percent yield is how much we actually get over how much we should have produced. So if we know the percent yield is 86% or 860.86 this is our actual yield. How much we got over 3.90 solving for X 3.40 grams.

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