how to determine if something is a weak or strong acid/base?

First, don’t use litmus paper. It measures the acidity, not the strength of the acid or base.

First, you need to know what an acid is. It is some substance dissolved in water, that exhibits the properties of acids.

Take for example hydrogen chloride (HCl). HCl dissolves in water to form hydrochloric acid. In the process, the H and the Cl break up, which is called ionization. We can say that the acid ionizes in water.

Strong acids are completely ionized in water, that means that all the HCl break up into H and Cl ions. More H ions means that the acid is more acidic. In fact, the pH value depends on the ratio of H ions to OH ions.

Weak acids, on the contrary, only partly ionize into H and other ions, called Acid Radicals. For example take ethanoic acid. It’s CHCOOH dissolved in water. What makes it weak is that only part of the CHCOOH breaks up into CHCOO ions and H ions. Some of it stays as it is.

The same applies to strong and weak bases.

There is a simple way to test it…measure the electrical conductivity of the acid/base, and compare it to that of the mineral acids (e.g. HCl).

Strong Vs Weak Acids

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RE:

how to determine if something is a weak or strong acid/base?

like C5H5NH+ or C9H7N…How do I know if these are weak or strong base/acid? I know that there’s a formula for it, but is their another way to know without using that formula? Thanks.

By the way, what is salt of a substance?

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The sad, simple answer is that you’re just going to have to memorize them. The happy, second answer is that you can (relatively) safely assume every acid will be weak unless it is one of these: HCl (hydrochloric acid) HBR (hydrobromic acid) HI (hydroiodic acid) HClO4 (perchloric acid) H2SO4 (sulfuric acid) (But only the first dissociation!!!) HNO3 (nitric acid) Likewise, here is a list of the most common strong bases: KOH (Potassium hydroxide) Ba(OH)2 (Barium hydroxide) CsOH (Caesium hydroxide) NaOH (Sodium hydroxide) Sr(OH)2 (Strontium hydroxide) Ca(OH)2 (Calcium hydroxide) LiOH (Lithium hydroxide) RbOH (Rubidium hydroxide) Mg(OH)2 (Magnesium hydroxide) Actually, on second thought, if the conjugate base is part of group 1 or 2, it’s probably a strong base. If it doesn’t fall under one of those lists, it probably isn’t strong. Now, here’s a couple other tips: Whenever you see the term "COOH" or "COO-" they are talking about a carboxylic acid. This is a whole class of weak acids. Whenever you see several carbon atoms bonded to one another, you’re probably looking at an organic compound. As far as I know, there aren’t any strong organic acids/bases. Uncharged amine groups are a great tip-off that it’s going to be a weak base.

Most of the previous answers may make you confuse.

My answer will even make you more confuse if you do not have good background on Acid – Base and Acidity – Basicity Concept.

C5H5N is Pyridine ( A Weak Base )

[ C5H5NH+ ] is Pyridinium Ion —- [ Conjugate Acid of Pyridine ]

C9H7N is Quinoline ( A Base ; But Stronger than Pyridine )

[ C9H7NH+ ] is Quinolinium Ion —- [ Conjugate Acid of Quinoline ]

Compare between two Bases :

For the Stronger Base —- Its Conjugate Acid will be Weaker Acid ( and vice versa )

Quinoline is a Stronger Base —- Its Conjugate Acid ( Quinolinium ion ) will be a Weaker Acid

Pyridine is a Weaker Base —- Its Conjugate Acid ( Pyridinium ion ) will be a Stronger Acid

Compare between two Acids :

For the Stronger Acid —- Its Conjugate Base will be Weaker Base ( and vice versa )

It helps to know structure of the substance. The first substance is probably pyradine (without the + sign), a cyclic organic with 5 CH groups and an NH group, where each group is at the corner of a flat hexagon (flat because of special bonding between adjoining groups). This is a weak base, much like ammonia (but a far more yucky smell). Pyradine can react with an acid to form the pyradinium ion C5H5NH2+ . This ion with the cation from the acid forms a salt.

the second answer is wrong. a strong acid always ionizes at a 100% rate and any acid that ionizes less than that is weak. it’s not a relative statement.

probably the easiest is to titrate the unknown with a solution of known straight.

The two compounds you listed can have several different compositions that would have different weak basic characteristics.

A salt is the combination of a metal and an acid radical like NaCl (Sodium Chloride) or common table salt. An Acid has a reactive hydrogen and a base has a reactive hydroxyl group

If hydrooxide ion Attached to Alkaline metals(group one ) then we get strong base and if hydrogen ion combined with elements which has high electronegativity then we get strong acid.

Well the strength of an acid or base can be compared by their pKa values. so a small pKa value is a stronger acid, whereas a high pKa value is weaker acid (but stronger base).

A salt of a substance is simply the ionic compound of the substance. Example: the salt of HCl can be NaCl NH4Cl

salts are produced by neutralization reaction of acids and bases

HCl + NaOH —-> NaCl (salt) + H20

NH4OH + HOAc —-> NH4OAc + H20