What Is An Acid?

26 Answers

Charlie Gilbert Profile
Charlie Gilbert answered
An acid is a species that is a proton donor and the word acid comes from the Latin word 'acidus' meaning sour. When an acid is added to water, it will give a solution with a pH of less than 7, pH is a measure of concentration of hydrogen ions in a solution. Most chemistry laboratories will have common strong acids, such as sulfuric acid (H2SO4), hydrochloric acid (HCl) and nitric acid (HNO3). Strong acids are acids that fully dissociates, and this means that it will be fully ionised in solution. Weak acids, that you are likely to come across everyday, includes ethanoic (acetic) acid which is in vinegar, methanoic (formic) acid which is in insect bites, and citric acid which is in citrus fruits). Weak acids are acids that partially dissociates and this means that it will only be partially ionised in solution.

All acids contain hydrogen and when an acid is added to water, the acid release H+ ions, also known as protons, into solution and as this happens with all acids, acids are known as proton donors. The H+ ion in an acid is the active ingredient and it is responsible for all reactions.

For example, HCl + solution (aq) ? H+ + Cl-

Bases are species that is a proton acceptor and reacts with acids to form salt and water. A salt is any chemical compound formed when a H+ from an acid has been replaced by a metal ion or any other positive ion. Positively charged ions, such as NH4+ are known as cations and anions are  negatively charged ions which derives from an acid in a salt. For example , hydrochloric acid goes to chloride salts, such as sodium chloride. 

A diprotic acid is an example of an acid that has two replaceable H+ ion and an example would be sulfuric acid. So if one proton from the acid is replaced then an acid salt is formed. For example H2SO4 goes to Na2SO4.

Salts can be formed from carbonates, bases and alkalis. An alkali is a type of base that dissolves in water forming hydroxide ions, OH- ions. Sodium hydroxide (NaOH), potassium hydroxide (KOH) and ammonia (NH3) are examples of alkalis When an acid reacts with a carbonate it produces a salt, carbon dioxide and water. When an acid reacts with a alkali or a base it produces a salt and water. Salts can also be formed from the reaction of reactive metals with acid in a reactions known as a redox (reduction and oxidation) reaction. When a salt is to be formed from the reaction of metals with acid a redox reaction takes place and this is when both reduction and oxidation take place. Oxidation is the loss of electrons and reduction is the gain of electrons. The metal from the reaction is oxidised, forming positive metal ions and the hydrogen in the acid is reduced. So if one species decreases its oxidation number, another species increases its oxidation number.
Sana Profile
Sana answered
An acid is a compound or a substance that increases the concentration of hydrogen ions. It is also said to be a proton donor. When an acid is dissolved in water, a solution is formed with a hydrogen ion activity greater than in pure water.
thanked the writer.
Anonymous
Anonymous commented
The proton donor thing is from using the bronston-lowry theory of acids and bases.
Anonymous Profile
Anonymous answered
Acids are the chemical compounds which realease Hydronium ions when dissollved in water.
Jai Khullar Profile
Jai Khullar answered
Acid is a substance which produces hydrogen ion on dissolving in water.
Anonymous Profile
Anonymous answered
An acid is a chemical compound or substance that release hydrogen ions in water solutions when dissolved!!
Anonymous Profile
Anonymous answered
An acid is a compound that allows hydrogen in it.
Sudipa Sarkar Profile
Sudipa Sarkar answered
Acid is a kind of substance soluble to water, tastes sour and changes the colour of acid base indicators, reacts with some metals to yield hydrogen gas. It reacts with bases to form salt from it by promoting certain chemical reactions, for example, if Hydrochloric acid (HCl) reacts with a base called Calcium Hydroxide [Ca(OH)2] it will form Calcium Chloride (CaCl2) and water (H2O).

2HCl + Ca(OH)2 = CaCl2 + 2H2O

Acid must have one or more hydrogen atoms as its content to positively charge hydrogen ions. There are several theories that give rise to alternative definitions of acids. According to Bronsted-Lowery definition, "An acid is a chemical that tends to release a proton (H+)". Lewis defined, "An acid is a chemical that can accept an electron pair from a base". According to this definition acid can be named as electrophite. In general, acids are divided into two subtypes – (1) inorganic acid such as Sulphuric acid (H2SO4), Nitric Acid (HNO3), Hydrochloric Acid (HCl) and (2) organic acid such as Carboxylic acid, Phenols, Sulphonic acid.
amber Jhon Profile
amber Jhon answered
An acid is represented by the formula HA [H+A] and it is a compound which when dissolved in water liberate hydrogen ions in water. An acid changes the pH of water or any solution and makes it lesser than 7. Martin Lowry and Johannes Nicolaus defined acid as a compound which gives Hydrogen ions to the other compound or base. Examples of acids include acetic acid, sulfuric acid etc.

Anonymous Profile
Anonymous answered
An acid a compound or substance that increase the concentration of hydrogen ion. It also a proton donor.
Anonymous Profile
Anonymous answered
An acid is a substance or compound that produce hydrogen ion as only ion when dissolve in water
Anonymous Profile
Anonymous answered
Acid is a compound that reacts with other materials forming new ones. Be careful it COULD be corrosive.
Anonymous Profile
Anonymous answered
According to brownsted law acid is a substance which donate a proton and base is a substance which accepts a proton
eg HCl =H+ + Cl- it will donate proton
Anonymous Profile
Anonymous answered
What are the natural source of the following organic acids.
1 lactic acid
2 ascorbic acid
Anonymous Profile
Anonymous answered
An acid is a substance that gives hydrogen ion when dissolved in water.In other words,it is a substance that gives salt when reacted with a base.E.g HCl,HBr etc

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