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

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SUMMARY

The correct reacting mass of magnesium (Mg) and chlorine gas (Cl2) to produce 119g of magnesium chloride (MgCl2) is determined through stoichiometric calculations. One mole of magnesium weighs 24g, while one mole of Cl2 weighs 71g. The total mass of reactants needed to achieve the desired product mass of 119g is 95g, which does not match any of the multiple-choice answers provided. The most plausible answer, based on the calculations, is 119g, although the question may contain an error regarding the quantities of reactants.

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  • Understanding of stoichiometry in chemical reactions
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  • Ability to perform basic algebraic calculations
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Homework Statement



Trying to help my son with this chemistry question.

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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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Your calculations are correct - 134 g is a right answer. There is something wrong with the test.
 
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.
 

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