Answer is
24.6
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Steps to help solve:
Step 1: Create a balanced equation for this synthesis reaction.
Here is a tip to help you get started N2 + H2 -> NH3 (*Don't forget to balance both sides*)
Step 2: Use Stoichiometry to convert the given mass of your first reactant(N2) to mass of your product(NH3). (grams to moles, moles to moles, moles to mass)
Step 3: Use Stoichiometry to convert the given mass of your second reactant(H2) to mass of your product(NH3). (grams to moles, moles to moles, moles to mass)
Step 4: Compare the two product values(from steps 2 & 3) to find out which value is larger(this will be your excess reactant) & which reactant is smaller (this will be your limiting reactant).
Step 5:Once you determine which reactant is limiting, use that mass of your product calculated as your theoretical yield.
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hope this helps :)