Differences Between Oxyacids and Ammonia with Examples
Oxyacids and ammonia are two very different chemical compounds or substances in comparison to one another. Let us try to understand what a chemical compound is? When several atoms of identical or similar molecules of at least more than one atom combine than they form chemical compounds. These molecules or atoms are held together by bonds called chemical bonds. Moreover, there are several chemical bonds such as covalent bonds, ionic bonds, metallic bonds etc. We can represent a chemical compound or its elements through a chemical formula specifying all atoms. For instance, the chemical formula of ammonia is \[NH_{3}\]. We can even change the composition of a compound by interacting it with a different mixture. This process is called a chemical reaction. Similarly, oxyacid and ammonia have a varying chemical composition as well. Now let us answer the question of what is an oxyacid?
What is An Oxyacid?
So what is an oxyacid? Oxyacid is a type of chemical compound that contains oxygen. In other words, they are the acids that carry oxygen and also known as ternary acid or oxoacid. To be more specific oxyacid contains oxygen, hydrogen, and one another element—the oxygen atom bonds with hydrogen atom producing anion of acid and H+ (hydrogen) cation. In the previous theory, scientists believed that all acids have oxygen in them, but later it was found that not all atoms have oxygen in them, for instance, hydrochloric acid. So the acids divide into two factions, hydro acids and oxoacids. These acids have an oxygen atom bound to a hydrogen atom, and these are non-metallic binary hydrides. We know for a fact that the acidic strength increases with the increase in oxygen atoms. In this case, the count of O atoms and electronegativity determines the acidity. The salts of oxyacids are comparatively more stable, such as oxyanions.
Some examples of these acids are hydrochloric acid, sulfuric acid, chloric acid, oxyacids of nitrogen etc. There are a variety of oxyacids of nitrogen such as nitric acid, nitroxyl, Nitroxylic acid, nitrous acid etc. now let us study and breakdown the structure of nitric acid. The structure of nitric acid is as shown in the figure below. It contains O (oxygen), N (Nitrogen) and H (hydrogen) atoms bound together. This acid has very high acidic properties and great oxidizing property.
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Properties of Oxyacid
There are several properties of oxyacids that everyone should be familiar with. To start with every oxyacid contains an oxygen-hydrogen structure (Y-O-H). Here Y is the central atom that connects all the other groups of atoms. We can dissociate the molecules of such structures in two ways.
Y-O-H ⇄ Y++ OH-[3]
Y-O-H ⇄ (Y-O)-+ H+
If the electronegativity of the central atom Y is quite strong so that it attracts the electrons of oxygen. Then oxygen and hydrogen bond is weak, easily ionizing as shown in the reactions above. Hydrogen gives an electron to become an ion, and thus Y-O-H becomes an acid. Furthermore, the number of O atoms and electronegativity of the central atom directly affects the acidic properties. For instance, among phosphoric acid, sulfuric acid, and perchloric acid. Based on the electronegativity of phosphorus, sulfur, and chlorine, the most potent acid is perchloric acid than sulfuric acid and lastly phosphoric acid.
Ammonia
Ammonia is one of the commonly known nitrogenous wastes. It is a compound containing hydrogen and oxygen atoms. The chemical formula of ammonia is given as \[NH_{3}\]. Also, ammonia is one of the most stable and straightforward hydrides or pnictogen hydrides. It is a gas with a pungent smell and colourless appearance. At average room temperature and pressure, the density of this gas is around half of the air. Our atmosphere contains only a tiny proportion of this gas, and the gases in a volcanic eruption also contain ammonia. They are also produced in the process of decomposition (of plants and animals). Its production, storage, and use in the concentrated form require high-level caution as it can be hazardous for health. The product that is used in households is mixed with water to reduce the concentration levels of the compound. The structure of ammonia (\[NH_{3}\]) is shown in the figure below.
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Properties of Ammonia
Ammonia is lighter than O (oxygen) with a pungent smell. The presence of hydrogen bonds between the atoms in this gas helps it liquefy easily. Its chemical reaction assists in the composition of various compounds of nitrogen. As you can see in the structure above the atoms of ammonia take a tetrahedron shape in its structure with one pair of unshared electrons. Its liquid form has a freezing point of -77.7 degrees Celsius and a boiling point of -33.3 degrees celsius. Some chemical reactions of ammonia make its salts such as acetic acid and sodium bicarbonate. It is also available in both solid as well as liquid form.
FAQs on Oxyacids and Ammonia Explained: Definitions, Properties & Applications
1. What is the fundamental difference between a hydracid and an oxyacid?
The key difference lies in their elemental composition. A hydracid is an acid that contains hydrogen and a non-metallic element, but no oxygen (e.g., Hydrochloric acid, HCl). In contrast, an oxyacid (or oxoacid) is an acid that contains hydrogen, oxygen, and at least one other element, which acts as the central atom (e.g., Sulphuric acid, H₂SO₄).
2. What are the key physical and chemical properties of ammonia (NH₃)?
Ammonia is a compound with distinct properties that are important in the CBSE syllabus. Key properties include:
- Physical Properties: It is a colourless gas with a characteristic sharp, pungent odour. It is highly soluble in water due to the formation of hydrogen bonds.
- Chemical Properties: Ammonia is a Lewis base due to the lone pair of electrons on the nitrogen atom. It reacts with acids to form ammonium salts. It can also act as a weak Brønsted-Lowry base in aqueous solutions, forming ammonium ions (NH₄⁺) and hydroxide ions (OH⁻).
3. What are some common examples of oxyacids of phosphorus and sulphur?
Oxyacids of phosphorus and sulphur are significant in p-block chemistry. Common examples include:
- Oxyacids of Phosphorus: Hypophosphorous acid (H₃PO₂), Orthophosphorous acid (H₃PO₃), and Orthophosphoric acid (H₃PO₄).
- Oxyacids of Sulphur: Sulphurous acid (H₂SO₃), Sulphuric acid (H₂SO₄), and Peroxodisulphuric acid (H₂S₂O₈), also known as Marshall's acid.
4. How is the strength of an oxyacid determined?
The strength of an oxyacid is primarily determined by two factors:
1. The oxidation state of the central atom: As the oxidation state of the central atom increases, its ability to pull electron density from the O-H bond increases. This weakens the O-H bond, making the proton (H⁺) easier to release and thus increasing the acid's strength. For example, HClO₄ (Cl oxidation state +7) is much stronger than HClO (Cl oxidation state +1).
2. The electronegativity of the central atom: For oxyacids with the same structure, the acid strength increases as the electronegativity of the central atom increases. For instance, HClO is a stronger acid than HBrO because chlorine is more electronegative than bromine.
5. Describe the structure of the ammonia molecule according to VSEPR theory.
The ammonia (NH₃) molecule has a trigonal pyramidal structure. The central nitrogen atom is sp³ hybridised. It forms three single covalent bonds with three hydrogen atoms. The fourth sp³ hybrid orbital is occupied by a lone pair of electrons. According to VSEPR theory, the repulsion between the lone pair and the bond pairs is greater than the repulsion between bond pairs, which compresses the H-N-H bond angle to approximately 107.8°, slightly less than the ideal tetrahedral angle of 109.5°.
6. Are oxoacids and oxyacids the same thing?
Yes, for the purposes of high school and introductory college chemistry (including the CBSE curriculum), the terms oxoacid and oxyacid are used interchangeably. Both terms refer to an acid that contains oxygen, hydrogen, and another element as the central atom. 'Oxyacid' is the more commonly used term in many textbooks.
7. Why is ammonia considered a good ligand in coordination chemistry?
Ammonia is an excellent ligand because it functions as a strong Lewis base. The nitrogen atom in NH₃ possesses a lone pair of electrons which it can readily donate to a central metal atom or ion to form a coordinate bond. This ability to donate an electron pair allows it to form stable coordination complexes, such as [Cu(NH₃)₄]²⁺ and [Ag(NH₃)₂]⁺.
8. What are the main industrial and laboratory uses of ammonia?
Ammonia has widespread applications due to its unique chemical properties. Its main uses are:
- Fertiliser Production: The vast majority of commercially produced ammonia is used to manufacture nitrogen-based fertilisers like ammonium nitrate and urea.
- Chemical Manufacturing: It is a crucial starting material for producing nitric acid (Ostwald process), sodium carbonate (Solvay process), and various polymers like nylon.
- Refrigerant: Due to its high heat of vaporisation, ammonia is used as a refrigerant gas (R-717) in industrial refrigeration systems.
- Cleaning Agent: Aqueous solutions of ammonia are effective household and industrial cleaning agents for removing grease and grime.
9. How does the number of oxygen atoms affect the acidity and oxidising power of oxyacids of chlorine?
In the series of chlorine oxyacids (HOCl, HClO₂, HClO₃, HClO₄), the number of oxygen atoms has opposing effects on acidity and oxidising power.
- Acidity: As the number of oxygen atoms increases, the oxidation state of chlorine increases (+1 to +7). This makes the O-H bond more polar and weaker, so the acidic strength increases. Thus, HClO₄ is the strongest acid in the series.
- Oxidising Power: The oxidising power depends on the stability of the oxyacid. Since stability increases with more oxygen atoms, the tendency to act as an oxidising agent decreases. Therefore, the oxidising power decreases down the series, making Hypochlorous acid (HOCl) the strongest oxidising agent.
10. Why is H₃PO₃ a dibasic acid while having three hydrogen atoms?
The basicity of an oxyacid is determined by the number of ionisable hydrogen atoms, which are those attached directly to an oxygen atom. In the structure of phosphorous acid (H₃PO₃), only two hydrogen atoms are bonded to oxygen atoms (P-O-H bonds). The third hydrogen atom is bonded directly to the central phosphorus atom (P-H bond). This P-H bond is not ionisable under normal conditions. Therefore, H₃PO₃ can only donate two protons, making it a dibasic acid, not a tribasic acid.
