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stoichiometry

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Maradona:
hi, im new and i need a little help...


The question

Zn + 2HCL --> ZnCl2 + H2



i have 2 questions on this.

If you had 100 grams of each reactant, which reactant would run out first?

How many grams of zinc chloride would you expect to make?


If able, please explanation would help.


Thanks,
Maradona

mike:
You must first calculate the number of moles (n) of Zn and HCl.

n=m/M

n is number of moles
m is mass
M is molecular weight

The number of moles will tell you which will run out first (this is called the "limiting reagent").

The number of moles of the limiting reagent will also be the number of moles of the product, ZnCl2, so you calculate the mass (m) of ZnCl2 produced by:

m=nM (from above)

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