# Chemical reaction

Consider the following Ca(OH)2 + 2NH4Cl → CaCl2 + 2NH3 + 2H2O (Source: https://chemiday.com/en/reaction/3-1-0-440)

It appears to be double displacement reaction as CaCl2 is formed, but it’s not as NH4OH is not formed instead NH3 is formed

Why NH3 is formed instead of NH4OH ?

Is there intermediate step which transform NH4OH into NH3( I don’t think so but still)

$$\ce{NH4OH <=>NH3 + H2O}$$, that is, they are in equilibrium. Since the solution is weakly ionized, (Kb is ~1.8 * 10-5 at 293 K), there is little $$\ce{NH4OH}$$ present at a given instant, so ammonia water is only weakly alkaline.
One might say the answer $$\ce{NH3 + H2O}$$ is 99.998% correct, but $$\ce{NH4OH}$$ is still 0.002% correct, not entirely wrong.