Question

What is the number of grams of NH3 produced when 25.0 g of N2 is reacted with exccess H2?
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Emely P. asked • 03/10/20

N2 + H2 → NH3 How many grams of ammonia are produced when 25 grams of hydrogen gas react with nitrogen gas?

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William W. answered • 03/10/20

TUTOR 5.0 (751)

BS in Mechanical Engineering with 35 years experience

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Step 1: Write a balanced chemical reaction equation

For N2 + H2 → NH3 we have two nitrogens on the left so we need two on the right, meaning we need to add a "2" coefficient in front of NH3 like this: N2 + H2 → 2NH3 . Now we have six hydrogens on the right so we need six on the left meaning we would need to write a "3" coefficient in front of the H2 like this:

N2 + 3H2 → 2NH3

Step 2: Turn the 25 g of hydrogen gas (H2) into moles by using the molar mass. The molar mass of hydrogen is 1.008 g/mole. so for H2 it is 1.008(2) = 2.016 gram/mole:

12.4008 moles

Step 3: Use the molar ratios to find the moles on ammonia produced

The balanced chemical reaction equation says that for every 3 moles of H2 there are 2 moles of NH3 produced. So:

8.2672 moles of NH3

Step 4: Calculate the grams of ammonia using the molar mass.

The molar mass of ammonia (NH3) is 14.007 + 3(1.008) = 17.031 grams/mole so:

140.7986 grams NH3

There are 2 sig figs in the given 25 grams H2, so we round the anwser to 2 sig figs so 140 gram NH3