M.7

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shevanti_kumar_1E
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M.7

Postby shevanti_kumar_1E » Sun Oct 25, 2020 5:27 pm

For M.7 Solid boron can be extracted from solid boron oxide by reac- tion with magnesium metal at a high temperature. A second prod- uct is solid magnesium oxide. (a) Write a balanced equation for the reaction. (b) What mass of boron can be produced when 125 kg of boron oxide is heated with 125 kg of magnesium? I am confused on what the limiting reactant is.

When I did my calculations Mg seemed to be the LR but I checked the back of the book and I think it used B2O3 as the LR to get the answer.

Izamary Marquez 2H
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Re: M.7

Postby Izamary Marquez 2H » Sun Oct 25, 2020 6:22 pm

Once you have your equation for the reaction balanced out, you need to look at the ration of one molecule to the other (if there's two i.e this case). Then, once you solve for the actual amount, whichever one limits the ratio it should have is the limiting reactant.

Eliot Kagan 2G
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Re: M.7

Postby Eliot Kagan 2G » Sun Oct 25, 2020 6:43 pm

The LR for this problem would be Mg because the weight of 3 Mg's are greater than the weight of B2O3. The book seems to also use Mg as the LR so you may have done your calculations wrong.

lwon Dis2I
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Re: M.7

Postby lwon Dis2I » Mon Oct 26, 2020 7:59 pm

The book seems to use B2O3 as the LR because it uses that reactant to solve for the mass of boron produced.

Problem:
Solid boron can be extracted from solid boron oxide by reaction with magnesium metal at a high temperature. A second product is solid magnesium oxide. (a) Write a balanced equation for the reaction. (b) What mass of boron can be produced when 125 kg of boron oxide is heated with 125 kg of magnesium?

I got magnesium as the limiting reactant so I thought we should be using that to solve for the mass of boron produced, not B2O3.

Can someone please clarify what I did wrong or what I am misunderstanding?
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Sami Siddiqui 1J
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Re: M.7

Postby Sami Siddiqui 1J » Mon Oct 26, 2020 10:04 pm

lwong Dis1L wrote:The book seems to use B2O3 as the LR because it uses that reactant to solve for the mass of boron produced.

Problem:
Solid boron can be extracted from solid boron oxide by reaction with magnesium metal at a high temperature. A second product is solid magnesium oxide. (a) Write a balanced equation for the reaction. (b) What mass of boron can be produced when 125 kg of boron oxide is heated with 125 kg of magnesium?

I got magnesium as the limiting reactant so I thought we should be using that to solve for the mass of boron produced, not B2O3.

Can someone please clarify what I did wrong or what I am misunderstanding?


I'm getting that answer, too. I think the book picked out the incorrect limiting reactant. I checked the amount of product both of these reactants would make and also checked the stoichiometric ratios among the reactants and found Mg to be the limiting reactant. I think this error is actually on the textbook's editors if anything.

Sami Siddiqui 1J
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Re: M.7

Postby Sami Siddiqui 1J » Mon Oct 26, 2020 10:07 pm

Eliot Kagan 1A wrote:The LR for this problem would be Mg because the weight of 3 Mg's are greater than the weight of B2O3. The book seems to also use Mg as the LR so you may have done your calculations wrong.


In the textbook answer document provided on Sapling, I notice that it uses B2O3 as the limiting reactant. Using that as the limiting reactant would project a quantity of Boron that is simply too high for this reaction.

Sami Siddiqui 1J
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Re: M.7

Postby Sami Siddiqui 1J » Mon Oct 26, 2020 10:12 pm

Never mind, I didn't scroll down far enough on the document. It, indeed, shows Mg as the limiting reactant.


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