What is the Correct Reacting Mass of Mg and Cl2 to Produce 119g of MgCl2?

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In summary, the conversation is about a chemistry question involving the production of magnesium chloride. The correct amount of magnesium chloride produced is 95g, but the multiple choice answers do not include this option. Attempt 1 suggests using 100g of CL2 instead of 71g, resulting in 133.8g of magnesium chloride. Attempt 2 suggests that the problem may be with the test itself. The expert concludes that the correct answer is 134g and there may be an error in the question.
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CWatters
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Homework Statement



Trying to help my son with this chemistry question.

Question.png

Homework Equations


Given in the problem statement

The Attempt at a Solution


We think we have the first part right:

24g of Magnesium is one mol.
One mol of CL is 35.5g but we need one mol of CL2 so 2*35.5=71g
Then by conservation of mass 24+71=95g of Magnesium Chloride.

We definitely have a problem is with the last part of the question...

The multiple choice answers are 396g, 119g or 100g

Attempt 1:
100g of CL2 is used instead of 71g so we scaled up the magnesium as follows:
24 * 100/71 = 33.8g
So now the amount of magnesium chloride produced should be 100g+33.8g = 133.8g. But that's not an option.

Attempt 2

The problem doesn't actually mention changing the magnesium. In that case the amount of Magnesium chloride produced would be unchanged at 95g and some of the Chlorine would remain unreacted. But 95g isn't a valid answer either.

Discussion

396g seems way too high to be the answer. 100g is obviously wrong if 100g of Chlorine alone is used. So 119g seems like the most likely answer but how?
 
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  • #2
Your calculations are correct - 134 g is a right answer. There is something wrong with the test.
 
  • #3
Thanks. I worked out that if it had said 100g of magnesium instead of chlorine then the output would be 396g so perhaps that's the error in the question.
 

1. What is the chemical equation for the reaction between Mg and Cl2?

The chemical equation for the reaction between Mg and Cl2 is:
Mg + Cl2 → MgCl2

2. What is the molar ratio of Mg to Cl2 in this reaction?

The molar ratio of Mg to Cl2 in this reaction is 1:1. This means that for every 1 mole of Mg, 1 mole of Cl2 is needed for the reaction to occur.

3. How do the masses of Mg and Cl2 affect the reaction?

The masses of Mg and Cl2 directly affect the amount of product formed in the reaction. The amount of product increases as the masses of Mg and Cl2 increase, as long as the reactants are in the correct ratio.

4. Why is the reaction between Mg and Cl2 an example of a synthesis reaction?

The reaction between Mg and Cl2 is an example of a synthesis reaction because it combines two or more substances to form a more complex compound. In this case, Mg and Cl2 combine to form MgCl2.

5. What is the limiting reactant in a reaction between Mg and Cl2?

The limiting reactant in a reaction between Mg and Cl2 is the reactant that is completely used up during the reaction, limiting the amount of product that can be formed. In this reaction, the limiting reactant would be whichever reactant is present in the smallest amount, as it will be completely used up first.

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