Is ammonium chloride in water a physical reaction?
No, ammonium chloride in water is not a physical reaction. It is a chemical reaction.
Physical reactions are reactions where the substance does not change into a new substance; for example, boiling is something seen in a physical change, which occurs in a physical reaction. Other examples include density, mass, and volume.
Chemical reactions are reactions with chemical changes, such as bonds breaking. In chemical reactions new substances are formed and energy is given off or absorbed. Other examples include flammability, corrosiveness, and reactivity with acid.
With that, let's look at the equation this would form.
Ammonium chloride is is
Our reactants (or what we started out with) were ammonium chloride and water.
What we ended up with was ammonia and hydrochloric acid.
As you can see, our reactants and products differed, meaning that ammonium chloride in water is a chemical reaction, NOT a physical reaction.
Hope this helps!