[Chemistry Class Notes] on Sodium Nitrate Properties Pdf for Exam

An Introductory Note on Sodium Nitrate NaNO3 Properties

Sodium nitrate is an essential alkali metal inorganic nitrate salt which is water-soluble and mined in Atacama Desert to carry out several reactions in industrial scales. 

It is a chemical compound that is often found in pyrotechnics, fertilisers, food preservatives and rocket fuel. NaNo3 also serves as an easily available source of NO3 or nitrate anion. It is also practically insoluble in nitric acids. 

Sodium nitrate in water dissolves with endo-effect. However, it does not form crystalline hydrates. It is also categorised under INS number 251 number or E number E251. 

Since you know the chemical name of NaNO3, let us proceed with the other aspects of this chemical compound. 

Structure of NaNO3

NaNO3 compound name is for Sodium nitrate. Sodium nitrate structure includes an ionic bond between 1 Na+ ion and one NO3– ion. The structure looks as follows.

It is sodium salt of nitric acid (HNO3) therefore the nitrate ion contains the central nitrogen atom making bonding with three oxygen atoms via two single bonds and one single bond that are in resonance with each other. 

Also, you can look up to NaNO3 Lewis structure for better understanding of the molecular structure of nitrate ions. 

Lewis structure refers to the electron-dot diagram that is used to demonstrate the bonding between atoms in a molecule. The purpose of Lewis structure comprehends the molecule shape, its reactivity and how it interacts with other molecules. Along with that, it also shows the physical properties of any molecule like surface tension, boiling point, etc. In case of NaNO3, it contains both covalent and ionic bonds. 

Here is the Lewis structure of NaNO3

Occurrence of Sodium Nitrate NaNO3

NaNO3 is available naturally as huge mineral deposits (nitratine) in dry areas, especially in South American deserts. In Chile and Peru, it is found mixed with the mineral called caliche ore. Chile has the largest reserves of this ore, and there it is named as ‘white gold’. From there it has got its name ‘Chile/Peru saltpeter’.

Besides, some gold refiners utilise this component to produce aqua regia which can dissolve gold and several materials.  

 Sodium Nitrate Preparation 

The industrial synthesis action of NaNO3 takes place through neutralisation of nitric acid along with sodium carbonate or bicarbonate. 

2 HNO3 + Na2CO3 → 2 NaNO3 + H2O + CO2

HNO3 + NaHCO3 → NaNO3 + H2O + CO2

The preparation can also happen through neutralisation with sodium hydroxide. 

HNO3 + NaOH → NaNO3 + H2O

Another preparation procedure includes the reaction between NaNO3 and the mixture of a stoichiometric quantity of ammonium nitrate and sodium hydroxide, sodium carbonate or sodium bicarbonate.  

NH4NO3 + NaOH → NaNO3 + NH4OH

2NH4NO3 + Na2CO3 → 2NaNO3 + (NH4)2CO3

NH4NO3 + NaHCO3 → NaNO3 + NH4HCO3

These equations are equally vital to remember as what is the chemical formula for sodium nitrate. 

Properties of NaNO₃

Once you know what is NaNO3, it is vital to assess its distinctive features, both physical and chemical. NaNO₃ is a strong oxidising agent. It is incompatible with reducing agent, strong acids, metal powders, etc. It reacts violently with many non-metals, especially when it is in a molten state. 

Physical Properties

• It is a colourless, odourless, deliquescent solid.

• NaNO₃ is readily soluble in water.

• Sodium nitrate structure is crystallised, namely rhombohedral and trigonal. 

• Its aqueous solution is neutral towards litmus.

• NaNO₃ melting point is 308 C. 

• At the temperature of 20 degrees, the solubility of NaNO₃ is 74g/100 gm of water. 

• The boiling point of NaNO₃ is 380 C. 

• NaNO₃ is easily soluble in ammonia as well. 

 Chemical Properties

• NaNO₃ on heating loses a molecule of oxygen. 

• Sodium nitrate reacts with concentrate sulphuric acid to produce nitric acid. 

• It is an oxidising agent hence reacts readily with strong reducing agents and combustible agents. However, it is not combustible itself. 

• Its molar mass is 84.99/mole. 

• The density of NaNO₃ is 2.257 grams/cubic centimetre. 

It helps in the production of chromium and a few derivatives. Also, because of its high nitrogen content, it is used rapidly as fertilisers in fields. Several experiments till the date proved that it is capable of producing synthetic ammonia.  

Pyrotechnic Side of NaNO
3

It is not widely used in pyrotechnic compositions because of its non-hygroscopic nature. However, it can be used in fresh compositions for immediate use. It works really well when it is freshly prepared. NaNO₃ imparts a bright yellow colour to the flame that is characteristic colour of sodium ions.  

Application of NaNO3

Some of the uses of sodium nitrate involve in explosives, dental products, food preservatives, smoke bombs, wastewater treatments, fertilisers, salt substitute and several others. Apart from that following are some fields where NaNO3 is rapidly used. 

1. Plant Fertiliser- The nitrogen content in Nitrate is useful for plants as they absorb it from the soil and utilise it to make amino acids which are the primary source of protein. Therefore adding Nitrate in the soil helps in the healthy and rapid growth of plants.

Also, most vegetables and high degree water contain a considerable amount of Nitrate, and whenever we consume them, the Nitrate enters our body and benefits us. However, the accurate quantity of nitrate consumption varies from person to person, and it should not exceed the maximum limit. 

2. Food Additive- Sodium Nitrate In Food has been used for a long time. Especially preserving foods like meat and fish require nitrates and relevamt techniques, including some sort of dehydration. The main motive behind it is safeguarding the foods from bacteria attacks and eventual spoilage. 

One of the most significant qualities of sodium nitrate is that it resists the growth of Clostridium botulinum. It is known to be highly toxic and forms botulism, a great cause of paralytic illness and respiratory problems. 

NaNo₃ can also effectively maintain the organoleptic property of meats and helps in retaining the red colour of fresh meat. This chemical substance is equally essential for Dutch cheese and other canned meats and poultry.

Moreover, NaNO3, along with potassium and calcium nitrate, are capable of storing heat. Using this property, recently they are used in solar power plant for heat transfer.   

Often people confuse between these two chemicals. However, they are not the same. Following is the difference between them. 

Sodium Nitrate vs Sodium Nitrite

Did You Know?

An average human body of an adult contains approximately 250g of salt!

Safety/Health Hazards

Despite several therapeutic effects of NaNO3, there are a few health hazards associated with it. Therefore you should be careful while having foods that contain sodium nitrate. 

It is suggested that when we consume nitrate-rich foods, approximately 5% of that converts into sodium nitrite (NaNO2) in oral cavity by bacterial flora. This nitrite molecule is dangerous for human health as it is responsible for causing methemoglobinemia which has carcinogenic effects. 

• Methaemoglobinaemia– It is a disorder in which the level of methemoglobin rises in the blood. It is assumed that the presence of a high percentage of NaNO3 in body may lead to methemoglobinemia. The meats or cold cuts contain sodium nitrite that maintains the red colour of the foods through the oxidation of methemoglobin in them. Similarly, it causes oxidation of haemoglobin and causes this disorder. 

• Carcinogenic Effects– Sodium nitrite produces nitrosamines which are carcinogenic molecules. Clinical studies found out the close relation between dietary intake of nitrates and cancer in stomach. 

Test Your Knowledge

1. Which of the following chemical is used as stamp remover?

1. Sodium nitrate

2. Sodium chlorate

3. Potassium chlorate

4. Potassium nitrate

2. Which of the following chemical is used in processing Heroin, narcotic drug?

1. Acetic anhydride

2. Nitric acid

3. Hydrogen peroxide

4. Acetone

Answers: 1-d), 2-a). 

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