text problem 4J.5

[JosephineF]

it is asking to write the balanced formation reaction for NH3. The solution manual says 1/2N2 + 3/2H2 --> NH3. Is there a formula for how to arrive at these numbers or is it just guess and check? I'm confused as to how 2 Ns goes to only 1 N and how H2 gains another H

[Parker Smith]

the (1/2) N2 revers to only using a half mole of N2 (literally only one nitrogen molecule) to make one mole of NH3, which makes sense. Same applies with using (3/2) of the diatomic hydrogen to make one mole of NH3 (since 2x3=6 and 6/3=3, which lines up with the 3 hydrogen molecules in one mole of NH3)

[Ryan Yee 1J]

If you count up the total molecules in these equations, both sides have equal numbers of the required atoms. The 1/2(N2) means that there is only 1 nitrogen atom, and the 3/2(H2) means there are 3 hydrogen atoms, so they both come together to make 1(NH3)