Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: blondeface03 on March 07, 2017, 10:35:20 AM
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To make pepperoni pizza, you require the following ingredients: 1 crust, ½ can of sauce, 2 cups of cheese and 40 slices of pepperoni.
You have 5 crusts, 2 cans of sauce, 10 cups of cheese and 120 slices of pepperoni. Assuming you make the most pizzas you can with the given ingredients, identify all TRUE statements:
1) There will be excess cheese --- True!
2) There will be excess pepperoni
3) The theoretical yield of pizzas is 5
4) Cheese is the limiting reagent
5) There will be excess crust
6) Sauce is the limiting reagent
7) The theoretical yield of pizzas is 2
8) Pepperoni is the limiting reagent
9) There will be excess sauce
10) The theoretical yield of pizzas is 4
11) The theoretical yield of pizzas is 3
12) Crust is the limiting reagent
I'm having a hard time understanding this question beyond #1
Any help is gladly needed!
Thank-you all for your time!
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Not all of these statements can be true. For example 1 and 4 cannot both be true, nor can 10 and 11 both be true. I think a good place to start is to define what a limiting reagent is and what theoretical yield is. Next you should write a balanced equation for making a pizza based upon the first sentence.
EDT
I think that this problem is a good one for introducing students to concepts such as limiting reagent and theoretical yield, as well as a good way to show how units cancellation can be used in a systematic way in problem solving.
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One way to approach the problem is to go through each ingredient one by one and assume each is the limiting reagent, then calculate final yield of pizzas and the amount of other ingredients necessary. For example, if you assume crust is the limiting reagent, you will make five pizzas using 2.5 cans of sauce, 10 cups of cheese, and 200 slices of pepperoni. Obviously, you do not have all of these ingredients, so crusts cannot be the limiting reagent, so you move onto the next ingredient and repeat the procedure.
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Repeating what others have said, but in a different way,3,7,10,&11 can't all B true. Find out which one is true, answer that one as true, answer the others as false, and stop being daunted by this list. You can do #1, bit no others? They all ask the same question.