Hi Mark,
I think your chemical reaction is 2 NH3 + 3 CuO (g) → 3 Cu + N2 + 3 H2O. Going off this reaction, we can see that for every 2 moles of NH3 consumed, 3 moles of H2O are produced, and we can write the mole ratio of NH3 to H2O is 2/3. To find the number of moles of water (H2O) produced when 3 moles of NH3 are consumed, we can use the mole ratio:
moles NH3 / moles H2O = 2/3 = 3/n (n is the number of moles of water produced)
⇒ n = 3 * 3/2 = 4.5 moles of water produced.
Hope this helps,
Akshat Y.

Akshat Y.
06/16/21
Luke D.
Hello Mr. Akshat. Can you help me with two more questions please?06/16/21