Formed from the reaction of nitric acid (HNO3) with a metal, nitrate salts are no longer an unfamiliar term to chemistry enthusiasts. Nitrate salts are commonly found not only in chemistry exercises but also in everyday life. In this article, Goodheathplan.com will explore this topic with you, learn what nitrate salts are, and cover the theory in detail as well as some basic exercises.
What is the definition of nitrate salts?
Concept: Nitrate salts are salts of nitric acid. They are composed of the nitrate ion NO3– and cations. Nitrate salts are typically formed from the reactions of nitric acid with metals. Additionally, they are also produced by other cations such as NH4+.
Examples: In fact, each type of nitrate salt possesses different physical and chemical properties. Some common examples of nitrate salts include Sodium Nitrate NaNO3, Potassium Nitrate KNO3, Ammonium Nitrate NH4NO3, Calcium Nitrate Ca(NO3)2, Silver Nitrate AgNO3, Copper (II) Nitrate (Cu(NO3)2)…
General formula: M(NO3)n.
Physical properties of nitrate salts
All nitrate salts dissolve easily in water and are strong electrolytes.
They completely dissociate into ions in dilute solutions:
M(NO3)n → Mn+ + nNO3-
For example: NaNO3 → Na+ + NO3-
Chemical properties of nitrate salts
So what are the characteristic chemical properties of nitrate salts that you need to remember?
Learn the physical properties of nitrate salts.
Nitrate salts share the chemical properties of salt
Nitrate salts share common chemical properties with other salts. These properties include:
Reaction with acids
Nitrate salts react with acids to form new salts and acids.
Example: Ba(NO3)2 + H2SO4 → BaSO4 + 2HNO3
Reaction with bases
Nitrate salts react with base solutions to form new salts and bases.
Example: Mg(NO3)2 + 2NaOH → Mg(OH)2 + 2NaNO3
Reaction with salts
Nitrate salts react with salt solutions to form two new salts.
Example: Mg(NO3)2 + Na2CO3 → MgCO3 + 2NaNO3
Reaction with metals
Nitrate salts react with metals that are stronger reducing agents than the metal in the salt, forming new salts and metals.
Example: Cu + 2AgNO3 → Cu(NO3)2 + 2Ag
Thermal decomposition of nitrate salts
Nitrate salts are easily thermally decomposed and release oxygen. This is the reason why nitrate salts have a strong oxidizing property at high temperatures.
Nitrate salts of highly reactive metals (above Mg) such as potassium, sodium… will decompose to form nitrite salts + O2.
Example: 2KNO3 → 2KNO2 + O2(↑) (temperature)
Nitrate salts of moderately reactive metals (from Mg to Cu) such as zinc, iron, lead, magnesium, copper… are decomposed to form the corresponding metal oxides + NO2 and O2.
Example: 2Cu(NO3)2 → 2CuO + 4NO2(↑) + O2(↑)
Nitrate salts of metals below Cu will decompose to form the corresponding metal + NO2 + O2.
Example: 2AgNO3 → 2Ag(↓) + 2NO2(↓) + O2(↑) (temperature)
Note: In some cases, the thermal decomposition of nitrate salts does not follow the above rules, typically Fe(NO3)3, NH4NO3…
How to identify nitrate salts?
In a neutral environment, NO3- ions do not exhibit oxidizing properties. However, in an acidic environment, NO3- ions exhibit oxidizing properties equivalent to HNO3.
Therefore, to identify nitrate salts in a solution, a small amount of copper filings and dilute H2SO4 solution are added to the mixture and gently heated. The reaction produces a blue solution and colorless NO gas that is oxidized to brown-red NO2 gas.
Equation:
3Cu + 8H+ + 2NO3- → 3Cu2+ (blue solution) + 2NO(↑) + 4H20 (Conditions: temperature)
2NO + O2(air) → 2NO2 (brown-red gas)
How is nitrate salt prepared?
Nitrate salts are prepared by reacting HNO3 with metals, metal oxides, bases, or salts through ion exchange reactions (where the metal retains its oxidation state) or redox reactions (to form high oxidation state metal salts).
How to prepare nitrate salt?
What are the important applications of nitrate salts?
Nitrate salts have many important practical applications, and each different type of salt has its own unique characteristics and uses.
Sodium nitrate (NaNO3): This salt is most commonly used in chemical fertilizers (ammonium nitrate, potassium nitrate, and calcium nitrate) in agriculture, as well as in the production of nitric acid – one of the most important types of chemicals. Additionally, it is used with potassium nitrate as a preservative and in wastewater treatment technology.
Potassium nitrate (KNO3): The most notable application of potassium nitrate is in the manufacture of black powder, which is made up of 75% KNO3, 10% sulfur, and 15% charcoal. This salt is also used as a fertilizer for crops, a preservative for food, in the production of oxygen and nitric acid, as an additive in food, toothpaste, and more.
Ammonium nitrate (NH4NO3): This salt is used in the production of explosives, fertilizers, the processing of titanium ore, the production of N2O, and the manufacture of dry ammonia.
Calcium nitrate Ca(NO3)2: This salt is used to produce fertilizers and as an additive in concrete for construction. Its applications also include the production of rubber, wastewater treatment, cooling rooms, storing solar energy, and more.
4 common types of nitrate salts you should know
Nitrate salts are commonly seen not only in high school chemistry exercises but also in everyday life. Here are the 4 most common types of nitrate salts that you should know.
Sodium nitrate (NaNO3)
Sodium nitrate is one of the most common types of nitrate salts that appear.
Chemical formula: NaNO3.Physical properties:
Appearance: White crystals or powder. Colorless and slightly sweet taste.
Solubility: Highly soluble in water and liquid ammonia, slightly soluble in alcohol solutions, and easily decomposed.
Density: 2.257 g/cm3.
Melting point: 308°C.
Boiling point: 380°C.
Chemical properties:
Easily decomposed at high temperatures, producing sodium nitrite and oxygen.
Reacts with some acids. The products are a new salt and a new acid (in exchange reaction), gas, and water (in redox reaction).
Potassium nitrate (KNO3)
Another common nitrate salt is potassium nitrate, which has unique physical and chemical properties.
Chemical formula: KNO3.
Physical properties:
Appearance: White, odorless solid.
Solubility: KNO3 is highly soluble in water and slightly soluble in ethanol. The solubility increases with the temperature of the water.
Melting point: 334°C.
Boiling point: 400°C.
Chemical properties:
KNO3 is decomposed to produce oxygen.
Participates in redox reactions.
Example: S + 2KNO3 + 3C → K2S + N2 + 3CO2
In acidic environments, KNO3 reacts with other salts.
Example: 6FeSO4 + 2KNO3 (concentrated) + 4H2SO4 → K2SO4 + 3Fe2(SO4)3 + 2NO + 4H2O
Amoni nitrat (NH4NO3)
Ammonium nitrate is a compound formed by combining NH3 and HNO3. It possesses notable physical and chemical properties, including:
Chemical formula: NH4NO3
Physical properties:
Ammonium nitrate NH4NO3 typically exists as transparent, colorless crystals. However, it can also exist as a white powder under standard temperature and pressure conditions.
It is completely soluble in water and easily decomposes at high temperatures.
Chemical properties:
The thermal decomposition reaction is a characteristic chemical property of ammonium nitrate. It produces various products depending on the temperature.
Examples:
NH4NO3 → NH3 + HNO3 (at 110°C)
NH4NO3 → N2O + 2H2O (at 185-200°C)
2NH4NO3 → 2N2 + O2 + 4H2O (at 230°C)
4NH4NO3 → 3N2 + 2NO2 + 8H2O (at 400°C)
Calcium nitrate salt Ca(NO3)2
Next, let’s learn about calcium nitrate – one of the typical nitrate salts.
Chemical formula: Ca(NO3)2
Physical properties:
Calcium nitrate is a colorless inorganic compound that absorbs moisture from the air.
Melting point: 561°C (in anhydrous form) and 42.7°C in the tetrahydrate form.
Boiling point: It decomposes (in anhydrous form) and 132°C in the tetrahydrate form.
Ca(NO3)2 is soluble in ammonia but insoluble in nitric acid; it is more soluble in ethanol than methanol.
Chemical properties:
Decomposition reaction, producing calcium nitrite and oxygen as products.
It exhibits strong oxidizing properties when reacting with nonmetals such as S, P, etc.
Hopefully through the knowledge above, readers have understood what nitrate salts are, their applications, and become proficient in solving basic to advanced nitrate salt problems. Don’t forget to visit goodheathplan.com every day to not miss out on other interesting lessons in Math, Physics, and Chemistry! Wishing you an effective learning journey.
Johnny Jacks was born in 1985 in Texas, USA. He is the founder of Good Health Plan and is passionate about helping people improve their health and physical well-being. With over a decade of experience working in the healthcare industry, he currently works at Goodheathplan.com – a blog that shares knowledge on beauty and health.