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Oxyacids and ammonia are chemical substances that have completely different properties. We can define a chemical substance as a material with a specific chemical combination. It is a chemical compound composed of several identical atoms or molecules. The bond which keeps molecules together to form a chemical compound is called a chemical bond. Oxyacids and ammonia also have specific properties and uses. As the name suggests, an oxyacid is an acid that contains oxygen. An oxyacid is formed when a non-metal oxide reacts with water. On the other hand, ammonia is a colourless gas containing atoms of nitrogen and hydrogen.
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Key Terms: Oxyacid, NH3, Ammonia, oxygen, hydrogen, nitrous oxide, nitric oxide, carbon monoxide, non-metal, Boric acid
Oxyacid and Structure
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Oxyacid or acid-containing oxygen is also termed oxoacid or ternary acid. The combination of oxygen, hydrogen, and an element contains a minimum of one hydrogen atom coupled with oxygen. An oxyacid can be isolated in water to make the hydron (H+) cation along with the anion of the acid. There are some exclusions, like nitrous oxide, nitric oxide and carbon monoxide.
Read More: Benzene
Structure of Oxyacid
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An oxyacid is a combination of A, O and H. Where A is non-metal, O is Oxygen, and H stands for hydrogen. For example, H3PO3 or phosphorus acid is an oxyacid that contains hydrogen, oxygen, and phosphorus - a non-metal.
The structure of an oxyacid is based on the following two rules:
- Except for the oxyacid of phosphorus, the number of hydrogen (H) is equal to the number of OH. Every OH forms a single bond.
- Oxyacid of phosphorus contains P, the double bond of O, and one OH.
An example of an oxyacid is phosphorous acid. The following images show the structure of an oxyacid.
Figure: Structure of Phosphorous Acid
Read More: Cis-Trans Isomerism
Naming of Oxyacid
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Oxyacid is a compound having linkage A-O-H. Here, the atom of H is paired with the atom of O. A is a non-metal, and oxides of non-metals are acidic in nature. Hence is the name oxyacid. Parent oxyacids are considered while naming a new oxyacid.
Oxyacids are named in the form of “ic” or “ous” form. In oxyacids where the state of oxidation is higher, it is named with the suffix “ic”. In the lower state of oxidation, the “ous” suffix is added in the result. But, the naming of oxyacids is not limited to the higher and lower state of oxidation. The oxidation state can change when oxygen is added or removed. Other than that, if we add/remove water to an oxyacid it may change the structure and form.
Parent oxyacids have a higher state of oxidation, the following are some examples:
For Boron (B) family, it becomes H3BO3, Boric acid
For Nitrogen (N), it becomes HNO3, Nitric acid
For Silicon (Si), it becomes H4SiO4, Silicic acid
For Phosphorus (P), it becomes H3PO4, Phosphoric acid.
Figure: Structure of Phosphoric Acid
The examples mentioned above are in the form of parent oxyacid. If we decrease oxygen from any oxyacid, the state of oxidation also decreases. As a result, we get a lower oxidation state of that element, i.e., “ous” form. If we decrease one more oxygen, we will get the hypo form of that element, i.e., –hypo of –ous form. After that, by reducing H2O (intramolecular) from the “ous” form, we will get the Meta form of the “ous” form. Reducing water (intermolecular), we get Pyro form of “ous” form of that oxyacid.
Again, by removing H2O (intramolecular) from the parent oxyacid, we will get the Meta form of “ic” form. Also, by reducing water (intermolecular) we get Pyro form or “di” form of “ic” form. If we remove oxygen from the Pyro form of oxyacid, we will get the Hypo form of “ic” form. Again, adding oxygen in Pyro form will give “di” form of per “ic” form.
Above all, if we add oxygen directly into the parent oxyacid, we get perform / per oxy form of “ic” acid. This form of oxyacid is mono or single in nature. To illustrate naming properly, we have considered an example of Phosphoric acid (H3PO4) which is a parent oxyacid and can form various oxyacids.
Also, Read: Important Notes on Metals and Non-Metals
Properties of Oxyacid
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Y-O-H or oxygen-hydrogen is the structure of an oxyacid. In this, Y plays the role of a central atom which combines all other groups of molecules. We can separate the atoms of the Y-O-H structure in the following ways:
Y-O-H → Y++ OH-3
Y-O-H → (Y-O)-+ H+
The extent up to which an oxyacid gets dissociated in water decides the strength of an oxyacid. The relative strength of an oxyacid can be projected depending on its electronegativity and central atom’s oxidation number (non-metallic in nature). A rise in the electronegativity of the atom results in the rise of acidic strength.
Consider an example, chlorine’s electronegativity is considered to be higher than sulphur’s electronegativity, which is again higher than the electronegativity of phosphorus. When an oxyacid reacts with a base, it forms salts of an oxyacid. The solution made in this reaction is neutral, thus this type of reaction is termed neutralisation. Some examples of oxyacids are nitric acid, carbonic acid, and sulfuric acid.
Read More: Carbocation Stability
Ammonia and Structure
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Ammonia is a colourless gas with a pungent smell. It is a building block compound having atoms of nitrogen and hydrogen. The chemical formula for ammonia is NH3. NH3 is also a naturally occurring element in the environment.
NH3 is present everywhere- air, water, plants, soil, and animals, including human beings. The human body produces ammonia during the digestion of food. During the process, protein in the food is broken down into amino acids and NH3. After that, ammonia is converted to obtain urea.
Structure of NH3
Ammonia molecules has a trigonal pyramidal shape. It contains three atoms of hydrogen and two unshared electrons bonded with an atom of nitrogen. The Valence Shell Electron Repulsion Theory (VSEPR) is used to predict NH3 molecules. The theory works with an experimentally explained 106.7° bond angle. The inorganic compound acts as a weak base because it mixes with various acids to make salts. The following figure illustrates the structure of NH3.
Figure: Structure of NH3
Read More: Catalysis
Properties of Ammonia
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Ammonia is a polar type of molecule which is associated because of strong intermolecular bonding between hydrogen atoms.
| Particulars | Details |
|---|---|
| Chemical Formula | NH3 |
| Available in Form | Solid and liquid both |
| Density | 0.73 kg/m3 |
| Molar Mass | 17.031 g/mol |
| Boiling Point | -33.34 °C |
| Melting Point | -77.73 °C |
Uses of Ammonia
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- Industrial Use of NH3: Because of its heat-absorbing property, it is used in air-conditioning equipment as refrigerant gas. Other than that, the chemical compound is used in the purification of water supplies. NH3 is also a basic building block in the production of various products like fabrics, plastics, dyes, explosives, and pesticides. NH3 is used as an agent in the treatment of wastewater.
- For crops and plants: NH3 is a key element in ammonium nitrate fertilizer. It helps in releasing nitrogen, an important nutrient for the growth of crops and plants. It is used as a source of nitrogen.
- In household products: It is also known as ammonium hydroxide or household ammonia. Ammonium hydroxide is used as a key ingredient in various household cleaners for cleaning toilets, tubs, sinks, tiles, and countertops. The chemical compound is also popular for removing tough stains of food or beverages. Glass cleaning solutions also contain NH3 due to their property to evaporate in the air quickly.
Precautions
Exposure to NH3 may result in skin irritation and affect lungs or eyes. Even more, mixing of NH3 and chlorine bleach releases chloramines which are toxic gases. Chloramine exposure may lead to breathing issues, nausea, chest pain, irritation in the eyes, throat, and eyes. NH3 in concentrated form is caustic and dangerous. If a person swallows a cleaning product containing NH3, it may burn the food track including throat, mouth, and stomach. Also, the person may suffer from intense stomach pain.
Things to Remember
- In an oxyacid, an oxygen atom is coupled with an atom of hydrogen along with a minimum of one or another element.
- Second-period elements form oxyacid in sp2 hybridization whereas, the third-period elements form oxyacid in sp3 hybridization.
- An oxyacid is a composition of Y-O-H, where Y is the key atom. It together the entire group of atoms connects
- The power of an oxyacid is measured by its capacity to make H+ ions or the level up to which the acid dissociates in water.
- NH3 acts as a pH adjuster in the process of fermentation. Also, it is used as a neutralizer for pollutants released from diesel engines.
- The density of NH3 is less than oxygen. The gas can liquefy easily because of the hydrogen bonds present amid the molecules. NH3 is available in two forms – solid and liquid.
- The chemical reaction of NH3 helps in the formation of various compounds of nitrogen. Some of the chemical reactions of NH3 also result in the formation of its salts like sodium carbonate and acetic acid.
Also Read:
Sample Questions
Ques. Name the weakest and strongest oxyacid. (2 Marks)
Ans. The central atom’s negativity defines the strength of an oxyacid. Thus, the weakest oxyacid is Hypochlorous acid and the strongest oxyacid is perchloric acid. The main difference between the two acids is both have different numbers of O (oxygen) atoms in the structure. The acid having more oxygen atoms is a stronger oxyacid. Whereas, the weakest oxyacid has fewer atoms of oxygen.
Ques. List any three oxyacids of sulphur and give their structure. (6 Marks)
Ans. Oxyacids of sulphur and their structures are as follows:
H2SO3 - Sulphurous acid
H2SO4 - Sulphuric acid
H2S2O7 - Pyrosulphuric acid
Ques. What are oxoacids? Give some examples. (3 Marks)
Ans. Oxoacids are acids that contain oxygen. Notably, it is a chemical compound containing oxygen, hydrogen, and minimum one other element. Also, a minimum of one bond of the hydrogen atom is associated with the oxygen atom. Example – chlorine has four oxoacids namely hypochlorous acid (HOCl), chloric acid (HOClO2), chlorous acid (HOClO), and perchloric acid (HOClO3).
Ques. What is the main difference between oxo-acids and oxy-acids? (2 Marks)
Ans. Both oxyacid and oxoacid are acids that contain oxygen. An oxoacid has at least an atom of hydrogen bound to that of oxygen. The atoms dissociate with water to form HA cation along with an anion of oxoacid. Whereas, in oxyacid, a reaction between most covalent non-metallic oxides and water produces oxyacid that forms H3O+.
Ques. The reaction given below represents an oxoacid, Hn1S2On2, here,
S – central atom of sulphur,
N1 & n2 – natural numbers.
If it is possible to form two oxyacids of sulphur A and B having a ratio of n1:n2, i.e., 2:4. Then, what will be the sum of the oxidation state of the sulphur atom in A and B? (5 Marks)
Ans. For any oxyacid of sulphur the number of hydrogen atoms = 2
Thus, Hn1S2On2 - H2S2O3, H2S2O4, H2S2O5, H2S2O6, H2S2O7, H2S2O8.
For H2S2O4, n2 / n1 = 2; here the oxidation state of S atom is +3.
For H2S2O6, n2 / n1 = 4; the Oxidation state of the S atom is +6
Therefore, the sum of oxidation state will be 3+6. i.e., 9.
Ques. List four oxyacids of chlorine and write their formulae. (5 Marks)
Ans. In the periodic table, the second halogen is chlorine. Also, it has the same properties as iodine, bromine, and fluorine. Chlorine is one of the strong oxidizing agents. It reacts with other elements to form octets. The following are oxyacids of chlorine:
HOCl – It is hypochlorous acid which is also termed as chlorine hydroxide or hypochlorite.
HClO2 – It is Chlorous acid that contains one atom of chlorine and hydrogen, and two atoms of oxygen. HClO2 is a weak acid but a strong oxidising agent.
HClO3 – It is chloric acid that contains one atom of hydrogen, one atom of chlorine, and three atoms of oxygen. It is present in liquid form and has no colour. HClO3 is a strong oxidising agent and is used in the production of many chemicals.
HClO4 – This one is perchloric acid or hypercaloric acid. When used as an oxidizer, it helps to separate sodium and potassium.
Ques. How many hydrogen atoms are present in 34 grams of NH3? (5 Marks)
Ans. NH3 consists of one nitrogen atom bonded with three hydrogen atoms. The molar weight of hydrogen and nitrogen is equal to the weight of an atom of a similar element. The atomic weight of NH3 is 14g and that of hydrogen is 1g. Thus,
Molecular weight of NH3 = (1×14)+(3×1)
= 17g
17g of NH3 will contain 1mol. (as 1mol of any compound is the same as the molar weight of the compound)
Given that, we have 34g of NH3, using a formula for the number of moles we get,
n = w/Mw Where n is the number of moles, w is the weight of the compound, and Mw is the molar weight of that compound.
Putting values in the formula, we get,
n = 34/17 = 2 moles.
We know that one mole of NH3 has three hydrogen moles. Thus in 2mols of NH3, we will have 6 moles of hydrogen. (nH = 2 × 3 = 6 mol)
Also, the number of atoms in a single mole of an element is the same as the Avogadro number. Thus, hydrogen atoms in 6 moles of hydrogen is NH = 6 × 6.023 × 1023.
Ques. Write a balanced chemical equation for catalytic oxidation of NH3 by atmospheric oxygen. (3 Marks)
Ans. NH3 opposes combustion thus, it blows out a burning splint. Burning of NH3 in the air is not possible. But it can burn in O2 by giving out a flame yellowish-green in colour. This reaction with oxygen occurs when platinum is present at 800°C and gives out nitric acid with water. Here, platinum plays the role of a catalyst and this catalytic oxidation of NH3 is called an exothermic reaction. The chemical equation for catalytic oxidation of NH3 by atmospheric oxygen is as follows:
Ques. When passed slowly in water PH3 makes bubbles but NH3 dissolves. Give reasons. (2 Marks)
Ans. PH3 is insoluble in water and cannot build hydrogen bonds in water. Thus, PH3 produces bubbles when passed slowly in water. NH3, on the other hand, is soluble in water. Also, it can make hydrogen bonds with H2O (water). Thus, NH3 dissolves in water when passed slowly.
Ques. What happens when a person inhales NH3? (2 Marks)
Ans. Inhaling a higher quantity of NH3 may lead to breathlessness or respiratory failure. It can also result in the burning of the entire respiratory tract including the nose and throat. Other than that, irritation in the throat and nose may occur.
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