We encounter chemical compounds in our daily lives. Each chemical compound has its unique properties. Chemical compounds can be classified into three categories as acid bases and salts, based on pH value. Here in this article, we look at the definition, examples, properties, chemical reactions, and uses of acids, bases, and salts.
Acid Bases and salts:
- Acids
- Bases
- Salts
Acids are chemical compounds that are sour to taste. (Warning: Never taste chemical compounds.) They occur in fruits like lemons, oranges, grapes, apples, etc. Acidic compounds have different degrees of sourness depending on their acidic strength. Some are strong acids like hydrochloric acid (Warning: acids are corrosive), and some are weak like citric acids. Acids are corrosive in nature, meaning they can burn your skin even if it is a single drop.
Bases are chemical compounds that are bitter to taste. (Warning: Never taste chemical compounds) Some examples of bases include soap water, soda lime, baking powder, etc. Bases can also be corrosive in nature. Basic compounds are also commonly called alkaline compounds.
When acid and base react with each other then salts are formed. Salts like sodium chloride (the common salt NaCl) are found in nature in seawater. Many salts are also found in rock deposits and are called rock salts.
How do you determine whether a compound is an acid-base or salt?
Indicators are chemical compounds that help us to identify whether a compound is an acid-base or salt. Examples of indicators are litmus paper, litmus solution, methyl orange, phenolphthalein, etc. Indicators undergo an observable change like a change in color or precipitate formation that helps us to find the nature of the chemical compound.
Definition of Acids
Acids are chemical compounds that can dissociate to release a proton(H+) and have a pH less than 7 on the pH scale. They are sour to taste. Acids turn blue litmus paper red. Acids release hydrogen gas when they react with some metals. They can be highly corrosive in nature, so, should be handled with great care.
Examples of acids
Natural acids:
Natural acids are derived from organic substances like fruits, vegetables, and animals.
- Tartaric acid in tamarind
- The lactic acid in milk
- The citric acid in lemon, oranges, and other citrus fruits
- The acetic acid in vinegar
- Oxalic acid in tomato
Mineral acids:
Mineral acids which are derived from inorganic substances
- Hydrochloric acid (HCl)
- Sulfuric acid (H2SO4)
- Nitric acid (HNO3)
- Hydrofluoric acid (HF)
- Boric acid(H3BO3)
The reaction of acids towards indicators
| Indicator | Indication |
| Blue Litmus paper | Turns red |
| Phenolphthalein | Turns colorless |
| Methyl orange | Turn red |
| Turmeric | Turns yellow |
| Shoeblack flower | Turns pink |
Chemical properties of acids
- Acids react with metals to release hydrogen gas
- Yield hydrogen (H+)ions when dissolved in water
- Acids are corrosive in nature
- Acids react with metal carbonates to release carbon dioxide
- Acids react with metal hydrogen carbonates to release carbon dioxide
Uses of acids
Hydrochloric acid
- Refining of metals
- Synthesis of organic acids
- Neutralizing water in wastewater treatment and swimming pools
- dissolution of rocks in oil wells
Citric acid
- Used as a flavoring and preservative agent in food items.
- Used as a chelating agent in the hard-water treatment
- Used widely in cosmetics
Nitric acid
- Used in the synthesis of nitrogen-based fertilizers
- Used as an oxidizing agent in organic synthesis
- Used in the synthesis of aqua-Regia for cleaning of gold surfaces
Definition of Bases
Bases are chemical compounds that can dissociate to release a hydroxide ion (OH-) and have a pH greater than 7 on the pH scale. They are bitter to taste. Bases turn red litmus paper blue. They are soapy and slippery to touch, and can also be corrosive.
Examples of Bases
Water-soluble bases
These are generally hydroxides of alkali and alkaline earth metals.
- Potassium hydroxide (KOH)
- Sodium hydroxide (NaOH)
- Lithium hydroxide (LiOH)
- calcium hydroxide (Ca(OH)2)
- Barium hydroxide (Ba(OH)2)
- Strontium hydroxide (Sr(OH)2)
Water-insoluble bases
These are also bases but are not soluble in water.
- Magnesium oxide (MgO)
- Copper oxide (CuO)
- Schiff bases
The reaction of bases towards indicators:
| Indicator | Indication |
| Red Litmus paper | Turns blue |
| Phenolphthalein | Turns pink |
| Methyl orange | Turn yellow |
| Turmeric | Turns red |
| Shoeblack flower | Turns green |
Chemical properties of bases
- Bases react with metals to yield a salt and release hydrogen gas
- Yield hydroxide (OH-)ions when dissolved in water
- Bases react with non-metal oxides (e.g: NO2, CO2, SO2, etc) to yield a salt and water
- Bases react with acids to give salt and water
- Metal carbonate (a type of base) and metal hydrogen carbonate (a type of base) react with acid to give salt, water, and carbon dioxide
Uses of bases
Sodium Hydroxide
- Widely used in organic chemical synthesis
- Used as an industrial cleaning agent
- Used in wastewater purification for pH regulation
- Used in dissolving amphoteric metals like in the synthesis of aluminum by the Bayer process.
Calcium hydroxide
- Used widely in the food processing industry due to its low toxicity.
- Used in the construction industry commonly called slaked lime.
- Used in the synthesis of ebonite.
Sodium bicarbonate
- Used as an antacid to treat acid indigestion.
- Used as a leavening agent in baking
- Used as a pH regulator in swimming pools.
- Used as a fungicide
Definition of Salts
In chemistry, salt is formed as a result of the reaction between an acid and a base. It is always an ionic compound consisting of a positively charged ion called a cation and a negatively charged ion called an anion. For example: common salt(NaCl) is composed of sodium ion (Na+) as cation and anion chloride(Cl-) ion as anion. NaCl is the result of the reaction between HCl(hydrochloric acid) and NaOH (sodium hydroxide). Salt is a neutral compound and has a pH of 7. It will not change the color of litmus paper.
Examples of salts
Acidic salt
Acidic salts dissolve in water to produce acidic solutions. It is formed as a result of the reaction between a strong acid and a weak base.
- Sodium hydrogen sulfate (NaHSO4)
- Sodium dihydrogen phosphate (NaH2PO4)
- Potassium dihydrogen phosphate (KH2PO4)
Basic salt
Basic salts are the result of a strong base and a weak acid
- Potassium cyanide (KCN)
- Sodium hydroxide (NaOH)
- Zinc chloride hydroxide (Zn(OH)Cl)
Double salt
Double salts have a more than one cation or anion and have a very complex formula.
- Potassium cerium fluoride (KCeF4)
- Mohr’s salt
- Potassium Ytterbium iodide (K4[YbI6])
Mixed salt
Mixed is a salt consisting of two anions sharing a cation or two cations sharing an anion. It is a result of a reaction between more than one acid or base resulting in an imbalance in the number of cations or anions.
- Bleaching powder(Ca(ClO)2)
- Calcium disodium EDTA
Chemical properties of salts
- Neutral salts have a pH value of 7. Acidic salts have a pH value of less than 7. Basic salts have a pH value greater than 7. The pH of mixed salts and double salts depends on the number and type of cations and anions.
- Salts are basically insulators but when in a molten state or in solution they conduct electricity due to the association into anions and cations.
- Salts are highly soluble in water and other polar solvents. They dissociate into anions and cations.
- Salts are found as crystals with water molecules in them which can be removed by heating at high temperatures. These water molecules are called water of crystallization.
- Salts react with metal, if the metal is more reactive than the cation in the salt, then a cation exchange reaction takes place to yield another salt and metal.
- Salts react with acids, to undergo an ion-exchange reaction, and yields another acid and salt.
- Salts react with bases, to undergo an ion-exchange reaction, and yields another base and salt.
Uses of salt
Salts are used for many applications in industries, chemical synthesis, households, and agriculture. We will discuss the most commonly used salts ammonium nitrate(NH4NO3), sodium chloride(NaCl), and potassium dichromate
Ammonium nitrate (NH4NO3)
- Ammonium nitrate is widely used as fertilizer and preferred over urea due to its stability.
- It is a constituent of most of the major explosives like RDX, TNT, etc
- It is used in cold packs, it absorbs heat when reacted with water.
Sodium chloride (NaCl)
- It is used as common salt in our homes
- It is used for the synthesis of chlorine and sodium hydroxide
- It is used in the synthesis of sodium carbonate and calcium carbonate
- It is used in oil-well drilling to flocculate the drilling fluid.
- It is also used for water softening in the ion exchange process.
Potassium dichromate (K2Cr2O7)
- It is used in the synthesis of cleaning agents for glasswares.
- It is used as an ingredient of cement.
- It is used for many analytical tests in chemistry due to its bright orange color.
What is the use of categorizing chemicals into acids, bases, and salts?
Categorizing chemicals based on pH value help us to determine their physical properties like taste, feel, and form. Like, acids are sour to taste and bases are bitter. More importantly, we get knowledge about the chemical properties and determine the results of a chemical reaction without actually performing them.
The knowledge of acids, bases, and salts is very important during research studies as it gives us a fair knowledge of how the chemical is going to react. For example, in some cases, this could be dangerous like adding water to acids.
Do acids react with salts?
Salts react with acid to produce another acid and a salt. But the cations and the anions in the new salt and acid will be different.
Eg: 2NaCl +H2SO4 ——> Na2SO4 + 2HCl
What is the most powerful acid?
The pH of acids depends also on the concentration. Concentrated sulfuric acid is one of the most powerful acids. Recently, a research group from California has claimed to have synthesized the strongest acid called carborane acid [H(CHB11Cl11)]. [Ref- The strongest isolable acids by Mark Juhasz et al DOI:10.1002/anie.200460005]
What is the most powerful base?
Superbases like Lithium bis(trimethylsilyl)amide ((CH3)3Si)2NLi, butyl lithium, lithium diisopropylamide, sodium amide are thought to be the world’s strongest bases.
What is the pH of vinegar?
The pH of vinegar varies somewhere between 2 and 3 and varies upon the concentration of the solution. Vinegar is acetic and is sour to taste. The main component of vinegar is acetic acid.
Are acids, bases, and salts present in our body?
Yes, acids, bases, and salts are present in our bodies and are very vital for the normal functioning of our body organs. Like for example, our stomach has an acidic environment, and the intestines have a basic environment and the pH is vital for their healthy functioning. Our blood has a pH of around 7.4, a slight variation in pH can have an adverse effect on our body.
Examples of acids in our body: lactic acid, fatty acids, and amino acids like glutamic acid, etc
Example of bases in our body: Trypsin
Examples of salts in our body: Sodium and potassium salts.
What is the pH of common acid, bases, and salts?
The pH of acids bases and salts depends on their concentration. You can read this article to find the entire list of pH of chemicals with respect to their concentrations.
Are acids, bases, and salts safe to consume?
You should never taste or consume any chemical(acids, bases, or salts). The vapors of some strong acids can also affect your eyes and throat and can also affect your nasal passage. Acids and salts are both corrosive in nature. The extent of the impact may vary depending on their concentration. Salts can also cause an imbalance in our body and can affect our blood pressure.
What are the examples of acids, bases, and salts that we use in our kitchen?
- Acids in a kitchen: Vinegar, lime juicer, Jams, Jellies, Ketchup, etc.
- Bases in a kitchen: Sodium bicarbonate(baking soda), soaps for cleaning, antacids, etc.
- Salts in a kitchen: Sodium chloride, Monosodium glutamate, etc.
