[Chemistry Class Notes] on Sodium Carbonate Pdf for Exam [2024]

Sodium Carbonate is an inorganic chemical compound. Sodium Carbonate is a generic term for Soda ash. Soda ash is made from Trona.

Trona is a two-salt solution. It is composed of Sodium Carbonate and Sodium Hydrogen Carbonate that occurs in lakes as a result of evaporation processes.

The most important of all basic heavy chemicals is Sodium Carbonate, also known as washing Soda or Soda ash. It has various hydrated forms. It has a strong alkaline taste.

It has a significant advantage over Sodium Hydroxide. It is non-corrosive and thus safer to handle.

Is Sodium Carbonate Acid or Base?

Sodium Carbonate is a basic salt. It tastes strongly alkaline. It is a salt of carbonic acid and Sodium Hydroxide. As it is made of weak acid (carbonic acid) and strong base (NaOH) so, it is strongly alkaline in nature. Reaction is given below –

H2CO₃ + 2NaOH 🡪 Na₂CO₃ + 2H₂O

Carbonic Sodium Sodium Water

Acid Hydroxide Carbonate

Its solution turns red litmus paper into blue which confirms its basic nature. Its pH is about 10.52.

Formula, Properties, Structure, Synthesis and Uses

Formula

The chemical formula for Sodium Carbonate is Na₂CO₃. When dissolved in water, this inorganic molecule produces carbonic acid and Sodium Hydroxide. In its purest state, it is a white powder with no odour. It’s a strong base that can also be used as an antacid.

The Solvay process, Leblanc process, Dual-process, and Electrolytic process are the four methods for producing Sodium Carbonate.

Because it is a weak acid, it is only slightly soluble in ethanol and insoluble in alcohol. The use of Na₂CO₃ as a water softener is one of the most prevalent. The pH of the water is around 11.

Properties

Physical:

Sodium Carbonate	Na2CO3
Molecular Weight/ Molar Mass	105.9888 g/mol
Density	2.54 g/cm³
Boiling Point	1,600 °C
Melting Point	851 °C

Chemical:

Anhydrous Sodium Carbonate is unaffected by heat. It melts at 852oC without disintegrating.
The release of OH–(aq) ions during hydrolysis make Sodium Carbonate aqueous solutions somewhat alkaline.

Na₂CO₃(s) + 2H₂O(l) → H₂CO₃(aq) + 2Na+(aq) + 2OH–(aq)

Carbon dioxide from the air is absorbed by Sodium Carbonate aqueous solutions, which produces Sodium Hydrogen Carbonate.

Na2CO₃(aq) + H₂O + CO₂(g) → 2NaHCO₃(aq)

Carbon dioxide is formed when Sodium Carbonate reacts with moderate vegetable acids like lime juice.

Na₂CO₃(aq) + 2H+(aq) → 2Na+(aq) + H₂O(l) + CO₂(g)

Na₂CO₃(aq) + 2HCl(aq) → 2NaCl(aq) + H₂O(l) + CO₂(g)

Structure

Two Sodium atoms, three oxygen atoms, and one carbon atom make up each molecule of Sodium Carbonate.

The polyatomic Carbonate anion has a negative charge, whereas each Sodium cation has a positive charge.

As a result, Sodium Carbonate is a molecule with no charge.

Synthesis

Solvay Process

Historically, Sodium Carbonate was extracted from the ashes of plants grown in Sodium rich soil. Presently it is prepared by various methods such as Solvay process, Leblanc process, electrolytic process, Hou’s process etc. it is mined as well from several areas. The United States gets Sodium Carbonate mainly through mining which fulfills its domestic demand of Sodium Carbonate. Out of all these methods of preparation of Sodium Carbonate Solvay process is being used exclusively for the manufacture of Sodium Carbonate. So, we are describing the Solvay process here.

The Solvay process was discovered by Ernest Solvay, a Belgian industrial chemist, in 1861. It is more economical than other processes. It gives only calcium chloride as a waste product.

Solvay process is also known as ammonia-soda process. In this method, Carbon Dioxide and Ammonia are pumped into a chilled, saturated Sodium Chloride solution.

Sodium Hydrogen Carbonate, which is only very little soluble in the presence of Sodium ions, is virtually fully precipitated during the processes that occur. To make Sodium Carbonate, it is filtered out and burnt.

This procedure’s ingredients are inexpensive and widely available. The three main constituents are salt brine (NaCl), ammonia (NH₃), and limestone (CaCO₃). This technique produces a substantial amount of CaCl_2.

The reactions can be represented using the equation below. To make it, the hydrates are heated. It can also be produced by heating (calcining) Sodium Hydrogen Carbonate, as in the Solvay process:

2NH₃ + H₂O + CO₂ → (NH₄)₂CO₃

(NH₄)₂CO₃ + H₂O + CO₂ → 2NH₄HCO₃

When common salt is added to a solution containing NH₄+ and HCO₃–, NaHCO₃, the least soluble of the two, precipitates. It is then filtered out.

NH₄HCO₃ + NaCl → NH₄Cl + NaHCO₃

The Sodium biCarbonate is then heated to make Na2CO3.

2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O

It is possible to recycle the CO2 gas produced. When anhydrous Sodium Carbonate is dissolved in water, it recrystallizes to create washing Soda crystals that contain 10 molecules of water.

Uses

Few Uses of Sodium Carbonate are Listed Below –

It is largely used in production of detergents and soaps.
It is used in the manufacturing of glass.
It is used in the production of rayon polymers.
It is used as a food additive as an anticaking agent, raising agent, stabilizer etc.
It is used in cooking for example ramen noodles get their authentic flavor due to Sodium Carbonate.
It is used in the brick industry.
It is used in processing and tanning of animal hides.
It is used in toothpaste where it acts as a foaming agent.

It’s used to make water glass (Sodium silicate), borax, Sodium phosphate, and a range of other salt compounds.
It’s used to modify the pH of water.
Carbonate precipitates hard water, which contains magnesium and calcium ions, and is used as a water softener.
It can also be used as a laboratory standardisation reagent and as an analytical reagent.

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