Answer:

Explanation:
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In this case, since the undergoing chemical reaction is:

We first need to identify the limiting reactant given the masses of nitrogen and hydrogen:

It means that only 0.647 moles of ammonia are yielded, so the resulting enthalpy change is:

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The number at the bottom of each element on the periodic table represents the weight and or atomic weight.
Before you begin titration, drops of indicator are added to the Erlenmeyer flask. This happens when preparing to measure pH change.