How much MgO is formed when 10 kg of Mg reacts with 10 kg kg of O2

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Discussion Overview

The discussion revolves around a chemistry homework problem regarding the formation of magnesium oxide (MgO) from the reaction of magnesium (Mg) and oxygen (O2). Participants explore the steps necessary to determine the amount of MgO produced when 10 kg of Mg reacts with 10 kg of O2, focusing on concepts such as limiting reagents and stoichiometry.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant presents the balanced chemical equation for the reaction: 2Mg + O2 → 2MgO, and asks for guidance on the next steps to calculate the mass of MgO produced.
  • Another participant suggests starting by calculating the number of moles of Mg and O2, and emphasizes the importance of identifying the limiting reagent to determine the maximum yield of MgO.
  • A question is raised about how the problem is identified as a limiting reagents scenario.
  • A response clarifies that the differing weights of Mg and O2 imply that they will not produce equal amounts of MgO, highlighting the need to consider the limiting reagent.
  • It is noted that determining the limiting reagent is essential for calculating yield unless specific conditions are met, such as having only one reactant or being informed about the limiting reagent.

Areas of Agreement / Disagreement

Participants generally agree on the necessity of identifying the limiting reagent in this reaction to calculate the yield of MgO, but there is no consensus on the specific calculations or methods to be used.

Contextual Notes

The discussion does not resolve the specific calculations needed to determine the amount of MgO produced, nor does it clarify the assumptions regarding the purity of the reactants or the conditions of the reaction.

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Homework Statement


How much MgO is formed when 10 kg of Mg reacts with 10 kg kg of O2

The Attempt at a Solution



The balanced equation is:

2Mg + O2 [tex]\rightarrow[/tex] 2MgO

What do I do next? Do I find how many grams of MgO is produced by 10 kg of Mg and add it to the amount of grams that is produced by 10 kg of O2?
 
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First, you should find out the number of moles of Mg and O2 that you start with. Next, you need to figure out which is the limiting reagent (i.e. which reactant runs out first). For example, if you start with 4 moles of Mg and 4 moles of O2, you can only make 4 moles of MgO because you run out of Mg before you use up all of the oxygen.
 


How did you know it's a limiting reagents problem?
 


Because 10kg of Mg and 10kg of O2 will not produce the same amount of MgO in that reaction; 2 mol Mg and 1 mol O2 dont' have the same weight.
 


Whenever you need to figure out the yield of a reaction, you will always need to figure out which reagent is limiting unless 1) there is only 1 reactant or 2) they tell you which reactant is limiting (or which reactants are in excess).
 

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