As an necessary chemistry student you will discover yourself faced with acid/based concerns again and again.

You are watching: Is hno3 an arrhenius acid or base

From categorizing molecule to ranking their toughness without pKa or pKb values. This isn"t disastrous if/when you find out it correctly, however, your professor will assume you currently know this.

So s/he won’t teach it.


Because you’re expected to psychic this from ago in basic chemistry.

Instead her professor will fly through the material and expect girlfriend to keep up.

But this won"t aid with the acid/base classifications.

Simply memorizing meanings without true knowledge won"t do it any easier. Particularly when confronted with a molecule that shows up to fit much more than one acid/base definition.

So let"s take it a look in ~ acid/base interpretations in a much more logical way.

Categories of Acids and Bases

Before us dive in, be sure to download my complimentary acid/base cheat sheet to follow follow me now and also take through you to research on the go – organic Chemistry mountain Base Cheat Sheet

Acids and also bases will autumn under one or more the the complying with three categories:

Arrhenius acids/basesBronsted-Lowry acids/basesLewis acids/bases

The key here is to identify that while each group has a details definition, any kind of given molecule can fall into an ext than one category, some into all 3. Again, other we"ll watch at later on in this article.

Arrhenius Acid

An Arrhenius mountain is a molecule that when liquified in water will donate one H+ in solution. Merely put, a proton donor.

The trick come recognizing an Arrhenius acid is to look because that a molecule that starts through an H, and also typically contains an oxygen or halogen.

Common examples of Arrhenius acids include:

Hydrochloric acid – HClNitric mountain – HNO3Sulfuric mountain – H2SO4Acetic acid – HCH3CO2and so countless more…

An mountain dissociating in water does not type a free-floating proton. Rather one that the water molecule in systems will grab the H+ yielding a hydronium or H3O+ ion. Here"s what happens when nitric acid dissociates in water.


Arrhenius Base

An Arrhenius basic is a molecule that when dissolved in water will breakdown to productivity an OH- or hydroxide in solution. To identify the Arrhenius basic look for a molecule finishing in OH, yet not complying with CHx which describes an alcohol.

Arrhenius base examples include:

Sodium hydroxide – NaOHPotassium hydroxide – KOHMagnesium hydroxide – Mg(OH)2and so countless more…


But what if the acid/base is not liquified in water?

The Arrhenius an interpretation for acids and bases only refers come compounds liquified in water. Walk this typical that acids and bases cannot exist the end of water? not quite, that"s wherein the Bronsted-Lowry meaning comes in.

Bronsted-Lowry Acid

A Bronsted-Lowry acid, favor an Arrhenius acid, is a compound the breaks under to offer an H+ in solution. The only distinction is that the equipment does not need to be water. We can still refer to the exact same acids as noted for the Arrhenius acid examples, yet this time we"ll change the solvent come ammonia, alcohol, or noþeles else.

We observed what happens once nitric acid (HNO3) disappear in water. Now let"s view what happens once it disappear in ammonia (NH3) or even methanol (CH3OH)


Nitric mountain still liquified to productivity an H+ and also NO3-, however this time it was NH3 and also not water that picked up the free-floating proton.

Bronsted-Lowry Base

This is where we begin to view the difference in between the Bronsted-Lowry and Arrhenius definitions. If the Arrhenius basic referred especially to the hydroxide (OH-) ion, the Bronsted-Lowry basic refers to any atom or ion qualified of agree or bonding come a totally free proton in solution.

Referring back to the HNO3 + NH3 reaction above, once ammonia choose up the free H+ that acts as a proton-acceptor. NH3 is the Bronsted-Lowry base in this example.

Additional instances include:

Methanol – CH3OHFormaldehyde – H2COAnd also water – H2O

Lewis Acids and bases

The Lewis definition for acids and also bases is the most extreme because it"s not managing protons specifically. Instead the Lewis meaning deals v the movement of electrons.

Lewis Acid/Base Mnemonic

Think that Lewis as ‘lectrons"

Lewis Acid

A Lewis acid describes an atom or molecule the accepts an electron pair. Think ago to your ‘pushing arrows" for orgo mechanisms. Every time you draw an arrowhead representing the activity of electrons, the atom getting assaulted or agree those electron is the Lewis mountain in the reaction.

Common Lewis Acid instances in essential Chemistry

Borane – BH3 (hydroboration reaction)Aluminum Chloride – AlCl3 (electrophilic fragrant substitution reaction)Iron (III) Bromide – FeBr3 (electrophilic aromatic substitution reaction)and our good friend H+ (keep reading)

The drawing listed below is component of the EAS fragrant Halogenation reaction i m sorry you"ll view in late Orgo 1 or Orgo 2. Notice how the Fe gets attacked by a lone pair that electrons. By accepting those electrons Fe acts together a Lewis acid


Lewis Base

Since the Lewis an interpretation has to execute with the move of electrons, friend can guess by now that a Lewis base is an electron pair donor. As soon as again think earlier to your reaction mechanisms. The molecule making use of its electron to attack another atom is an electron pair donor and also a Lewis Base.

Here is the an initial step in acid catalyzed hydration. The pi bond attacking H+ provides the alkene a Lewis Base.


What If that Fits much more Than 1 Category?

After finding out the separation, personal, instance acid/base meanings you"re likely confused and overwhelmed.

So much information and also so very similar!

And what happens if a molecule appears to fit much more than one category?

For example:

Is OH- one Arrhenius Base? Or perhaps its a Bronsted-Lowry or even Lewis Base?

The answer is potentially all 3!

The definitions over evolved slowly as researchers were beginning to understand much more and an ext details around chemical reactions. The first is a an easy (no pun intended) definition, but the last 2 simply expand to right more complex solvents and also situations.

Take a look at the reaction below where the hydroxide ion strikes a proton on hydronium.


Arrhenius acid Definition: Hydronium breaks approximately yield an H+ in solution.

Arrhenius Base Definition: Hydroxide is one OH- dissolved in water.

Bronsted-Lowry acid Definition: Hydronium is an H+ donor regardless of solution

Bronsted-Lowry Base Definition: Hydroxide attacks and accepts the H+ indigenous hydronium.

Lewis acid Definition: The H+ on Hydronium accepts the attacking electron pair to form a bond.

Lewis base Definition: Hydroxide donates its electron pair to form a bond between itself and H+

Now that you know the similarities/difference between Arrhenius, Bronsted-Lowry, and also Lewis acids and also bases, exactly how do friend tell i beg your pardon is the more powerful or weaker acid? i m sorry molecule is more reactive? Which next of a reaction will be favored at equilibrium?

Learn this and much more in my acids and also bases tutorial video clip series:


In conclusion:

As an essential chemistry student you will be required to recognize and also classify 3 different species of acids and bases. Arrhenius, Bronsted-Lowry, and Lewis. When the technical definitions vary, as soon as you get the reasonable behind their definitions you"ll have the ability to quickly and also easily identify the different varieties of acids and also bases.

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Want to check your understanding of acids and bases? Click to shot the totally free Acid/Base exercise quiz.