Explain how you know that hno3 is an acid but nh4no3 is not an acid

An Arrhenius acid is a substance that dissociates in water to form hydrogen ions or protons (H⁺).

1)  Nitric acid (HNO₃) is a strong acid, because it completely dissociates in water and form a lot of hydrogen ions.

Dissociation of nitric acid in water: HNO₃(aq) → H⁺(aq) + NO₃⁻(aq).

2) Ammonium nitrate (NH₄NO₃) will disociate in water, but it will not give hydrogen cations.

Dissociation of ammonium nitrate in water:

NH₄NO₃(aq) → NH₄⁺(aq) + NO₃⁻(aq).

HNO3 is the monoprotic acid and completely dissociate in water and gives the H+.

Dissociation of Nitric acid in water:  HNO3→ H+ + NO3-

In NH4NO3 Ammonium is formed by a weak base and is therefore a relatively stronger acid.

Nitrate is formed from a strong acid and is therefore an extremely weak base.  

Therefore the overall Compound is slightly acidic. The salt of a strong acid (HNO3) and a weak

Base (NH3) is acidic.

The chemical equations:

NH4NO3(s) → NH4+ (aq) + NO3-(aq)

NH4+ (aq) <==> NH3 (aq) + H+ (aq)

(The second equation favors products slightly due to the presence of NO3- continuously joining with the H+ ions and then separating again. This is what causes an acidic pH)

Explanation

Arrhenius Acids and Bases

1.An acid is a substance which dissociates in water to produce one or more hydrogen ions (H+).

2.A base is a substance which dissociates in water to produce one or more hydroxide ions (OH-).

Brønsted-Lowry Acids and Bases

1.An acid is a substance from which a proton (H+ ion) can be removed. Essentially, an acid donates protons to bases.

2.A base is a substance to which a proton (H+) can be added. Essentially, a base accepts protons from acids.

Acids that can donate only one proton are monoprotic, and acids that can donate more than one proton are polyprotic

So according to Arrhenius and Bronsted-Lowry Acid and Base concept HNO3 is the strong monoprotic acid

And NH4NO3 is the salt of Strong acid and weak base so it is slightly acidic in nature.

When in solution, ammonium nitrate will dissociate very well into NH4+ and NO3-. The ammonium ion is a Bronsted-Lowery acid in that it will donate an H+ to solution. In turn, this forms ammonia (NH3). Ammonia being a weak base will accept hydrogen ions from the solution, but not all of them. In conclusion, the solution will form an equilibrium where the pH is slightly acidic due to H+ ions being loose in solution.