Properties of Acids and Bases

A molecule capable of creating a covalent bond with an electron pair is an acid. Acids are very commonly found in some of the foods we consume like, for example, citrus fruits such as oranges and lemons, which contain citric acid; vinegar contains acetic acid; in fact, our stomach uses hydrochloric acid for digestion. Acids have a sour taste. It reacts with metals to form H2 and reacts with carbonates to form a salt, carbon dioxide and water. Acids turn blue litmus paper red. Acid's strength can be measured on the pH. Acids are sticky. Acids frequently cause nose burning. 


Properties of Acids and Bases

Here, we will learn about the basic properties of acids and bases later, we will learn about the chemical properties of acids and bases and also physical properties of acids and bases. Acids are a different group of compounds because of the properties of their aqueous solutions. Properties of acids are as follows:

  1. Acids can conduct electric currents because of the electrolyte nature, and some acids are strong electrolytes because they can completely ionize in water producing many H+ ions.

  2. Acids are sour. Oranges, lemons, and vinegar are few examples.

  3. Acid changes the color of a few acid-base indicators. Two common indicators of acids are litmus and phenolphthalein. Acid turns blue litmus into red, and phenolphthalein turns colorless.  

  4. Acids react with metals to produce hydrogen gas.

Zn(s) + H2SO4(aq) → ZnSo4(aq) + H2(g)


Properties of Bases are: 

  1. Bases can be strong or weak. Base's aqueous solutions are also electrolytes. 

  2. Bases are often bitter. Soaps are less common as foods but are present in many household products. Soaps are an example of the base, which is slippery.

  3. Bases change the color of indicators too. Litmus paper turns blue, and phenolphthalein turns pink.

  4. Bases do not react with metals like acids.


How do Acids and Bases React With Metals?

Acids react with most metals to produce salt and hydrogen gas. As we know, metals that are more active than acids can undergo a single displacement reaction. 


Zinc metal reacts with hydrochloric acid and produces zinc chloride and hydrogen gas.

Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)


Bases too react with few metals like zinc or aluminum to produce hydrogen gas. 

Sodium hydroxide reacts with zinc and water to produce sodium zincate and hydrogen gas.


Zn(s) + 2NaOH(aq) + 2H2O(l) → Na2Zn(OH)4(aq) + H2(g)


Chemical Properties of Acids and Bases

Like we learned about the basic properties of acids and bases, now we will learn about the chemical properties of acids and bases. We will learn what happens when bases meet metals and acids meet metals.


Chemical Properties of Acids:

  1. Acids react with Reactive Metals Like the Followings:

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Acid + metal → salt + hydrogen

Copper and silver do not react with dilute acid.

Like:

2HCl(aq) + Mg(s) → MgCl2(aq) + H2(g)

  1. Acids React with Bases

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Acid + Base -> salt + water

6HNO3(aq) + Fe2O3(s) → 2Fe(NO3)3(aq) + 3H2O(l)

This is the reaction of acids and bases with metals.

  1. Acids React with Carbonates

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Acid + carbonate => any salt + water + carbon dioxide

H2SO4(aq) + CuCO3(s) →CuSO4(aq) + H2O(l) + CO2(g)

So these are the chemical properties of acids and bases.


Physical Properties of Acids

So, here are the physical properties of acids :

1.  Acids are sour.

2.  Acids are water-soluble.

3.  Solutions of acids can turn blue litmus paper to red.

4.  Acid solutions have pH values lesser than 7.

5. React with metal carbonates to produce salt carbon dioxide and water.


Solved Examples

Question 1: What happens when you mix an acid and a base?


Solution: When an acid and a base are placed together, the process of neutralization takes place—acids and base's reaction causes the neutralization of the acid and base properties. Neutralization is a process when acid and base are combined together; salt and water are produced. Such as when NaOH reacts with HCl, the product formed is NaCl and H2O. Here, NaCl is salt.


Question 2: Are all bases alkaline in nature? Justify your answer.


Solution: The term 'alkaline' is usually used for basic solutions, but they are not meant to be the same. All bases are not alkaline because all bases are not soluble in water, and alkalis are best known as bases that dissolve in water to form hydroxyl ion (OH-), and all are Arrhenius bases. Usually, water-soluble alkalis, such as barium carbonate, become soluble in water only when they react with an acidic solution containing water. Bases are generally a chemical substance that can accept H+ ions. 


Fun Facts

We can identify an unknown chemical as an acid or base by using a wet litmus paper into it. Litmus paper makes acid red and bases blue. A litmus paper is treated with an extract from a certain lichen that changes color according to pH. Both acids and bases can neutralize each other. strong bases can have slippery feeling. Vitamin c is also a kind of acid known as ascorbic acid.

FAQ (Frequently Asked Questions)

Question 1: What is a Strong Acid?

Answer: When acid is marked as a strong acid, it actually does not matter how powerful and how corrosive it can be. The strength of acid actually refers to the ability to release hydrogen ions into a solution. Strong acids are one which completely dissociates into their ions into the water, which means all of their molecules break up in a settlement. Strong acids produce at least one hydrogen cation(H+) per molecule. We can identify weak acids like it will dissociate less than 1%, which indicates that very few of their units will break up to release a hydrogen ion.

Question 2: Why are Acids Called Proton Donors?

Answer: Acids are chemical substances that donate H+ ions to bases. Since a hydrogen atom is an electron and a proton, so an H+ ion is just a proton; therefore, acid is a 'proton donor,' and a base is a 'proton acceptor.' The reaction between an acid and base is a proton transfer. Acids do not 'donate' hydrogen ions; they surrender them. 

For example: HA(aq) + H2O(l) → H3O+(aq) + A-(aq)

                     (acid)        (base)      

The acid gives a proton (H) to the base (H2O) thus giving products of H3O (with extra proton) and A- (without one proton deducted). Hence, acids are called proton donors.