How to tell if a chemical formula is an acid or a base

Whether it is an acid or a base depends on the specific definition of the acid and base, and it also depends on the specific reaction.

The simplest definition is a compound in which the cation is entirely hydrogen ions when ionized in solution.

In the acid-base proton theory, any molecule or ion that can release protons is an acid, and any molecule or ion that can accept hydrogen ions is a base.

In Lewis acid-base theory, the substance that accepts one electron pair is an acid, and the substance that can give one electron pair is a base.

The key is to see under what definition you are analyzing.

Those that contain acid ions are acids, and general acids start with H. Those that contain hydroxide ions are bases, which generally end in OH.

There are hydroxide radicals that must be alkalis, and there are some special aqueous solutions like sodium carbonate that are alkalis, and the rest, like hydrochloric acid, and sulfuric acid, are definitely acids, but in fact, there are not many acidic and alkaline things, there are a lot of salts, and if it is a precipitation, it is not to mention acidity and alkali.

Acids contain element H and bases contain OH roots.

Strong who is strong, such as Na2CO3, Na strong is alkaline, ammonia chloride, chlorine is strong and acidic, almost strong neutral, or because of hydrolysis weak acidity and alkalinity.

Test strips, 7 are acidic, = 7 neutral and 7 alkaline. 2. The universality of acid and base. 3. When a chemical reaction occurs, it is hydroxide ion ( ) or hydrogen ion ( ).

The cation only H is an acid, and the anion is only oh is a base.

It is an acid that is generally composed of hydrogen ions and acid ions, and an alkali is composed of metal ions and hydroxide ions.

The one with hydroxide (OH) is the base.

See if the ions electrolyzed are H+ anions are oh-

1. Acid: cations are all hydrogen ions, the general chemical formula is only H in front, organic matter H is in the back such as hydrochloric acid (HCL), cations are hydrogen ions, anions are chloride ions, and no other cations are included, so they are acids; Another example is acetic acid (CH3COOH), acetic acid is partially ionized, and the cation ionized is only hydrogen ions, so it is an acid.

2. Alkali: The anions are all oh-, followed by hydroxide.

For example, sodium hydroxide (NaOH), its cation is sodium ion, and the anion is only hydroxide ion, so it is a base.

3. Salt: cation is metal or ammonium, anion is acid.

For example, sodium chloride (NaCl), the cation is a metal sodium ion, and the anion is a chloride ion (the acid group of hydrochloric acid), so it is salt.

Cry, salt is the combination of acid anion and metal cation. Such as NACL

Acids are generally H+ acid groups (e.g., H2CO3 carbonate, HNo3 nitrate, etc.) and bases are generally metal elements + OH (e.g., NaOH sodium hydroxide, Ca(OH)2 calcium hydroxide, etc.).

SO4 is a sulfate group that belongs to the atomic group, and other common atomic groups are PO4 phosphate, CO3 carbonate, etc.

H2SO4 is sulfuric acid.

Hydrochloric acid is HCl

The acid root means that it is an atomic group, and all the atomic groups should be preceded by H, and not all those who add H are acid roots.

Salt is very special, he is not a sour root. As long as a compound contains both metals and acid groups, it is a salt.

It can be written according to the chemical formula.

Junior high school is relatively simple, acid: contains.

The only du] oxygen ionization

The sub is hydrogen ion (daoh+); The alkali contains the [only] version of the anion hydroxide ion (right OH-)! You can roughly judge it by looking at its chemical formula;

For example, HCl (with H+) is acid, but NaHCO3 also has H+, but H+ is not the only oxygen ion, it also has Na+, so it is not an acid, it is a salt.

For example, NaOH (with OH-) is a base, but: ammonia NH3 H2O, OH- can not be seen, but it is also a base, because it is soluble in water, and the only anion OH- can be ionized.

By the time you reach high school, there are many definitions of acid-base!

Ionization theory: Any compound that can ionize H+ in water is an acid, and a compound that can ionize hydroxide in water is a base.

Proton (i.e. H+) theory: everything that can give protons is an acid, and everything that can accept protons is a base! (According to proton theory, sodium carbonate is a base because it can react with H+).

These theories will interfere with each other, and the scope of definition is not fixed, which will lead to errors in the judgment of some compounds, which should be specified by specific substances, but there are few objectionable substances, and most of them can still be judged.

If you mean according to plagiarism.

Judging by the chemical formula, the chemical formula of the acid is usually left.

is H, and the chemical formula of the base is usually oh to the right. Such as:

Acids and alkalis. hcl naoh

hno3 koh

h2so4 ba(oh)2

acid-base indicator, litmus reagent (test strip); Phenolphthalein reagent.

pH test strips. There are also specific phenomena produced by the reaction of some specific substances.

For example, Na2CO3 will produce bubbles when it encounters acid, etc.

From the chemical formula bai: cationic du is a compound that is all hydrogen ions, and it belongs to acid. Such as daohno3 h2so4

Anions are all compounds of hydroxide ions.

It is a base inside. Naturely.

Look: 1) Use purple litmus test solution, what makes litmus red is acid, and what makes litmus blue is alkali 2) Use pH test paper to measure pH, > 7 alkaline, < 7 acidic There are many other methods, which are relatively simple.

Acid is a substance that ionizes H+ in aqueous solution, and the main ones used in junior high school are sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, and acetic acid.

Alkali is a substance containing OH- in aqueous solution or molecule, mainly sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide, ammonia, magnesium hydroxide, copper hydroxide, iron hydroxide, etc.

The acidity and alkalinity of salt depends on the anion and cation group, if the cation is strongly alkaline, such as Na, K, etc., and the anion is weakly acidic, such as CO32-, then the salt is alkaline.

Conversely, if the cation is weakly basic, such as NH4+, and the anion is strongly acidic, such as NO3-, then this salt is a substance that shows that acidic acids are a class of substances that ionize and produce cations that are all hydrogen ions.

Alkali is a class of substances that produce anions when ionized, all of which are hydroxide ions.

According to their definition, we can distinguish them:

Hydrogen ions can make purple litmus red, but hydroxide roots can make purple litmus blue, so the way to distinguish it can be to add purple litmus dropwise.

Hydrogen ions cannot change the color of colorless phenolphthalein, while hydroxide ions can make colorless phenolphthalein red, so dropwise addition of colorless phenolphthalein can also be distinguished.

Note: Acids can discolor the indicator, but it is not necessarily an acid that can discolor the indicator, it may be an acidic solution. The same is true for alkalis.

If you judge by the chemical formula, then you should pay attention to two points:

1.Whether or not there is hydroxide (or hydrogen ions) in this chemical formula.

2.Whether the cations in the subchemical formula are all hydrogen ions (or the anions are all hydroxide ions).

For example: NaHCO3 sodium bicarbonate, it is not an acid, because although it has hydrogen ions, its cations are not all hydrogen ions, and it also contains sodium ions, so it is not an acid.

Another example: Cu2CO3(OH)2 basic copper carbonate, he is not a base, because although he has hydroxide, its anions are not all hydroxide, and it also contains carbonate, so it is not a base.

What is hydroxide is a base The chemical formula H starts with an acid except for H2O.

The cation (anion) ions produced by ionization are all hydrogen ions (hydroxide ions), and the compounds are acids (bases).

With purple litmus reagent, it turns red when exposed to acid and blue when exposed to alkali.

Acid or base can react with the indicator to make the indicator show different colors, the acid can make the purple litmus solution turn red, but can not change the color of the colorless phenolphthalein solution, but can make the purple litmus solution turn blue, and make the colorless phenolphthalein turn red.

Regarding how to judge the acidity and alkalinity of a substance, there are four definitions of acidity and alkalinity in university textbooks.

One is that it is an acid that can provide H ions, and vice versa.

The second is that the cation in the solution is only H ion, which is an acid.

The third is that it is an acid that can donate electrons, and the opposite is a base.

Fourth, it is sour that has a sour taste.

These four methods can determine the acidity and alkalinity of a substance.

Of course, experimentation is the foundation of all reason.

If it's high school, it's enough to memorize those few substances, and the dozen or so substances will be given to you next time.

Hydrogen ions plus acid ions are acids.

Such as H2SO4

HNO3HCL et al.

Metal ions plus hydroxide ions are bases.

e.g. naohca(oh)2

Cu(OH)2, etc. kca

NABA is a strong base, and other metals are weak bases. ClSO4NO3 is a strong acid and CO3 is a weak acid.

Strong alkali and weak salts are alkaline.

Such as na2CO3

K2CO3 is a strong acid and a weak alkali salt, which is acidic.

Such as znso4

FeCl3 is a strong base and a strong acid is neutral.

Such as naclkcl

Weak acid and weak alkali salts are neutral.

Such as (NH4)2CO3

It should be gone, and I will add it if I have a problem.

pH greater than 7 alkaline.

Less than 7 acidic.

Those with hydroxide are alkaline.

Those with hydrogen ions are acidic.

There are two commonly used reagents for the identification of acidity and alkalinity, phenolphthalein and litmus, litmus reagent changes color when acid, turns blue when alkalin, phenolphthalein does not change when acid, and turns red when alkalin. You can also use pH test strips to compare with standard color charts.

Three common strong acids: hydrochloric acid (HCl), sulfuric acid (H2SO4), nitric acid (HNO3), acetic acid, carbonated acid, silicic acid, and common weak acids.

Common strong bases: sodium hydroxide (Naoh), potassium hydroxide (KOH), ammonia, iron hydroxide, ferrous hydroxide, ammonia monohydrate, copper hydroxide, silver oxide, magnesium hydroxide, aluminum hydroxide, zinc hydroxide.