H2S polar or nonpolar: H2S is considered slightly Polar because of the similar electronegativity values of sulfur and hydrogen atoms but due to electronegativity difference it is mainly considered nonpolar. One of the reasons which make it a polar molecule is also because 2 lone pairs that are present on the opposite side of hydrogen atoms make a bent geometrical structure and makes it more polar as a molecule H2S.
What is H2S?
H2S is called hydrogen sulfide which is a colorless gas with a pungent smell but only at low concentrations. As we know that H2S is a chemical formula for the hydrogen sulfide compound Is inhaled by humans In large amounts which makes it poisonous.
Hydrogen sulfide H2S can react With oxygen and heat making it combustible to produce sulfur dioxide SO2. If hydrogen sulfide gas is inhaled it can react in the cellular respiration and stop it from the process of respiration. Its toxicity is as strong as carbon monoxide which is very dangerous and causes a health hazard in humans.
What is polarity?
Polarity can be described in a nutshell as in chemistry the measure of how evenly the electrons are distributed in a molecule. Now the question is how do elements and compounds attract electrons? The answer is quite simple that all the elements have different EN and this electronegativity present inside them allows them to attract electrons when they form a covalent bond.
The more they have electronegativity inside them the more they attract electrons. And automatically the polarity of that compound is found by the evenness of distribution of electrons in a molecule. When the electrons are displaced unevenly it gives the compound of each element a partial positive electron and a partial negative electron.
The element that shares more electronegativity will be given a partial negative charge and the element that shares less electronegativity will have a partial positive charge. This calculation is a polarity of an element or compound. The formation of the polar or nonpolar bonds depends on the respective electronegativity of both elements.
For example, if the electronegativity difference between 2 elements is 0.5 or 2 then the compound or bond which is made out of these two elements is considered polar. But if the difference is less than 0.5 then they are automatically considered a nonpolar bond.
Example
The molecule of water with the chemical formula of H2O is significantly considered a polar bond. Because the negativity of hydrogen is 2.1 and oxygen has ab electronegativity 3.5 and the difference between these two values is 1.4 which makes the bond polar. And oxygen is left with a partial negative charge.
Explanation on hydrogen sulfide and its polarity
Now that we know how to calculate the polarity of a bond we can use that lesson in explaining the polarity of hydrogen sulfide H2S. As we already know that hydrogen in this bond has an electronegativity value of 2.1 and sulfur carries an EN value of 2.5.
Now considering these two EN values, the difference between these two and they’re electronegativity is less than 0.5 which clearly makes them nonpolar bonds. The entire molecule is considered nonpolar because of the very less electronegative difference between H2S Elements.
Now it can be a little confusing but the twist is that H2S bonds are not completely nonpolar. As mentioned in the above paragraph, Sulfur has more electronegative value than hydrogen so it does pull electrons to itself. It does show very weak polarity and is mostly considered in nonpolar bonds. But in some circumstances, H2S bonds can show weak polarity because of sulfur.
Compound of hydrogen sulfide
The compound of hydrogen sulfide is made as a result of 1 sulfur atom and two hydrogens atoms. The atom of sulfur is central and two atoms of hydrogen are terminal in the compound. The compound of hydrogen sulfide is just like a water molecule that has a bent geometrical structure.
Hydrogen sulfide as a compound can be explosive in the presence of oxygen and heat and is proved to be denser than air. Hydrogen sulfide can be weakly soluble in water and can act as a weak acid. Hydrogen sulfide has very high combustion qualities and will react with heat and oxygen to form water h2o and sulfur dioxide so2.
At high temperatures, the sulfur dioxide created by hydrogen sulfide can be turned into pure elemental sulfur. This method is mainly used to obtain pure sulfur. And then later on it reacts with metal ions to create lead PB and lead sulfide PBS.
Occurrence and production of hydrogen sulfide
Hydrogen sulfide is obtained through different methods and the three main sources of hydrogen sulfide production are explained below:
Through Anaerobic respiration
The process of activation of sulfidogenic bacteria is the main source of hydrogen sulfide production. Bifidogenic bacteria use sulfur ions instead of oxygen for respiration and to carry electrons. The sulfate ions at the end of the reaction produce hydrogen sulfide as a byproduct Which is released into the atmosphere.
These hydrogen sulfide products which are produced at the end of the reaction of bifidogenic bacteria respiration are the causes of pungent or rotting smell in places where a large quantity of decaying matter Is found like sewers and marshes. The production of pure elemental sulfur is very important for living organisms and the process of bifidogenic bacterial respiration is a very important step in the sulfur cycle.
Through these types of processes, sulfur makes its way into living organisms and back to the environment. Production of hydrogen sulfide through geological activity Small amounts of hydrogen sulfide can be produced through a geological process That involves the crust of the earth.
Because it is proven that large quantities of sulfur and sulfur minerals are found in the crust of Earth. The metal sulfides found inside the surface react In the presence of heat and pressure to create hydrogen sulfide gas and metal oxides through hydrolysis with water.
The earth itself creates this pure form of hydrogen sulfide gas through the process of hydrolysis and the production of natural gases takes place by these natural events like thermal ocean vents.
Occurrence of hydrogen sulfide in humans
We know that hydrogen sulfide can be toxic and poisonous for humans in large quantities but a small amount of hydrogen sulfide plays a very important role in the human body.
Hydrogen sulfide is responsible during the cellular respiration process to act as a signaling molecule to regulate ATP production. Hydrogen sulfide is also very important for the process of seed germination.
Hydrogen sulfide and its toxicity
As I mentioned before, hydrogen sulfide can be very toxic in nature for those who breathe oxygen and use oxygen as a main source of respiration. Hydrogen sulfide’s toxicity is compared with carbon monoxide which is very dangerous.
Hydrogen sulfide can react and bind with enzymes that work during the process of cellular respiration and when this type of interruption happens inside the body it can be really dangerous and almost fatal.
And as we know that a very small amount of hydrogen sulfide is produced inside a human body so the body and its system consist of some defense mechanisms that work against hydrogen sulfide but if the presence of hydrogen sulfide is in large quantities then it can beat the defense mechanism of the human body.
Hydrogen sulfide poisoning symptoms
Hydrogen sulfide gas is denser than air so the presence of this gas can sometimes be detected by the body and sometimes not. A large quantity and greater concentrations of hydrogen sulfide can be detected through a rotting smell. As we know that it is poisonous so if a human body consumes or breathes in a lot of hydrogen sulfide gas and it can be fatal.
Here are some symptoms that might help you recognize hydrogen sulfide poisoning before it’s too late:
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Just like carbon monoxide poisoning, hydrogen sulfide poisoning can also cause symptoms like lack of concentration and focus.
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Dizziness and fatigue are also some of the poisoning symptoms.
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Irritability and memory loss.
The most dangerous thing about hydrogen sulfide gas poisoning is that it does not take much time to be inside a human body and it immediately starts damaging the brain. If you witness or ever go through hydrogen sulfide poisoning you should immediately go to the doctor and they will try to get it out of your system.
In the past, extreme poisoning of hydrogen sulfide was diagnosed by putting a copper coin inside the patient’s pocket and if the patient is poisoned by hydrogen sulfide the coin in his or her pocket will turn green because hydrogen sulfide will oxidize the coin. And that is how they indicated the poisoning of hydrogen sulfide in the human body.
Hydrogen sulfide properties
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Hydrogen sulfide is a toxic gas and is proven to be colorless in nature. It does not have any color which makes it hard to recognize its existence.
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Hydrogen sulfide can be produced as a byproduct of industrial waste and is also found in sewers and marshes.
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Hydrogen sulfide can smell like rotten eggs in lower concentrations. In this state, it can smell pungent and rotten and can be recognized as hydrogen sulfide gas.
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It is soluble in water and other liquids as well. When hydrogen sulfide is dissolved in water it produces hydro sulfuric acid.
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This gas has very high combustion properties and can produce high flame requiring only 4% of concentration. Hydrogen sulfide gas shows high explosive properties.
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Hydrogen sulfide gas is relatively denser and heavier than air and due to this reason, it is found in areas where there is little to no ventilation.
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Hydrogen sulfide has a boiling point of minus 60.4 degrees Celsius.
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One of the contradicting properties of H2S is that it shows nonpolar behavior and sometimes because of sulfur it shows polar qualities.
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Hydrogen sulfide reacts with metals easily to form metal sulfides.
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For oxygen inhalers and living things that consume oxygen for respiration, it can be very dangerous, toxic, and fatal if the gas is in high concentration and large quantity.
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Hydrogen sulfide also shows corrosive properties which means it tarnishes and turns copper into green by oxidizing it.
Uses of hydrogen sulfide gas
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In the human body it plays a very important role in the signaling pathways for cellular respiration.
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Hydrogen sulfide is mainly used for mass production of sulfuric acid and sulfur.
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For elemental sulfur hydrogen sulfide is used as a precursor.
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Hydrogen sulfide is used as a disinfectant by farmers for agricultural processes and is usually found in some cutting oils which are used for making lubricants. These oils and lubricants are of different types which are used for machines And mechanical processes.
Structure of hydrogen sulfide H2S
The structure and physicality of hydrogen sulfide H2S are explained through the chart below:
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|—|—|—|
|Name of molecule |Hydrogen sulfide|
|Structure| Bent shape|
|Polarity | Non-polar and polar at different times|
|Number of lone pairs| Two|
|Valence electrons|Eight|
|Molar mass| 34.1 gram per mol|
What does it mean by polar molecule?
A molecule is considered to be neutral and does not have any charges of its own. That molecule is polarized when one side of the molecule has a higher concentration of electronegativity which attracts electrons. Basically, one element in a molecule has more negative charge than the positive Charge.
The geometrical structure of a polar molecule is uneven because of the difference in the distribution of negative ions across the element. For example, the water molecule H2O has an uneven structure chemically.
Water molecule is considered a polar molecule because oxygen as a central atom has more electronegative energy than hydrogen. So oxygen attracts more negative charge than hydrogen which makes it a polar molecule.
How to differentiate between nonpolar and polar molecules?
The basic identification of a polar molecule is its uneven distribution of electrons also known as negative charges while the opposite side has positive charges. Meanwhile, a nonpolar molecule is identified by equally distributed charges on both sides of a molecule. A very interesting example of this contradiction is the molecule of oxygen.
Oxygen has very high properties of electronegativity but it is still considered a nonpolar. The reason behind this is that both of the molecules of oxygen share the same amount of electrons or charges. For a molecule to be polar only one side of the molecule should have a more negative charge.
So in the case of O2, both sides have equal electrons which makes it a nonpolar molecule. Molecules that contain the same type of elements like H2, CL2, and N2, etc. are considered dipoles. Automatically molecules that contain elements like carbon and hydrogen are considered nonpolar for example methane and ethane.
Electronegativity and its importance
In a chemical bond if the electronegativity of both the elements have a difference of more than 0.5 is considered a polar bond. The electronegativity of an element is important because it gives them the strength to attract negative charges and complete their shell and gain a negative charge.
In the chemical bond of hydrogen sulfide H2S, We know that with sulfur having an atomic number of 16 it attracts both the electrons of hydrogen to complete its shell. Through this attraction of electrons, sulfur becomes more electronegative than hydrogen and gained a negative charge leaving hydrogen with a positive charge.
The rate of electronegativity increases from left to right on a periodic table. this means that hydrogen has electronegativity of 2.20 and sulfur has an electronegativity of 2.58.
So the difference between the electronegativity is 0.38 respectively which makes it a nonpolar bond due to its difference in EN values being less than 0.5. Sulfur being a more electronegative element in a compound than hydrogen makes it a dipole situation.
Hydrogen sulfide and hybridization
According to Drago’s rules statement is that hydrogen sulfide technically has no hybridization. Drago’s rule states that: Hybridization or mixing of orbitals in a molecule is not possible if the energy difference between both the atoms and their atomic orbital is too high.
But some conditions allow the hybridization to take place in a molecule. Following are some rules and conditions for the mixing of orbitals to take place.
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With one or more lone pairs, the central atom should be in 3rd orbit or lower For a possible hybridization.
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The surrounding atoms should have an electronegativity value of 2.5 or more.
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No positive charge should be present in the central atom of the molecule.
Unfortunately, this rule does not work for all the molecules and chemical bonds. These rules are valid only for Six molecules that are PH3, SBH 3, AsH3, H2s, H2Se, and H2Te. Clearly, H2S hydrogen sulfide does not pass all these conditions as we know that Sulfur is a central atom and has two lone pairs.
It has no positive charge while having hydrogen on both sides with the electronegativity of 2.1. And in addition to this rule mentioned above, the difference between the vacant sulfur orbital and the first orbital of hydrogen is too high which gives more reasons to why hydrogen sulfide has no hybridization taking place.
Hence, it is confirmed that hydrogen sulfide has no orbital mixing or hybridization.
Frequently Asked questions
Some related questions are answered below:
1. What shape is H2S?
The central atom in the H2S molecule is sulfur which is bonded to two hydrogen atoms so the shape of H2S is bent.
2. What happens when H2S is mixed with water?
The mixture of hydrogen sulfide and water can create weak acids. Hydrogen sulfide alone cannot cause any disastrous mixtures with water and therefore is used to create weak acids and It’s proven to be corrosive while being the source of hydrogen ions.
3. Is H2S combustible?
Hydrogen sulfide gas which is also known as Stink damp and sewer gas because it is found in marshes and sewers. This gas has proven to be very toxic and highly flammable in nature which means that it is combustible. As it is also naturally found in volcanoes.
4. Is H2S an acid or base?
H2S is a Lewis acid because to form an O_H bond in hydronium ion it accepts a pair of electron. And because H2S donates a proton to a water molecule, it is considered to be a weak acid specifically brønsted acid.
5. Is H2S symmetrical or asymmetrical?
The electronegativity difference between hydrogen and sulfur is 0.4, so they are nonpolar bonds. The molecular geometry of hydrogen sulfide H2S is asymmetrical as they have no sign of polar bonds in their molecule.
Conclusion
What we learned about hydrogen sulfide H2S polar or nonpolar behavior is that the polarity of a molecule can be calculated after considering certain factors. For example, how the bond polarity can affect the basic polarity of a specific molecule. By Determining the direction of the polarity of a molecule. We can easily find out the polarity of a molecule by studying the structure and detecting it by symmetrical and asymmetrical structures of the molecule. Hydrogen sulfide H2S is considered to be a polar molecule when the molecule is determined to have a central atom of sulfur which makes a bent structure. Hydrogen and sulfur in H2S molecule having uneven distribution of electrons make it a polar molecule. Sulfur is relatively more electronegative than hydrogen but the difference of polarity between hydrogen and sulfur is 0.4 which is less than 0.5 and technically makes them a nonpolar molecule. This dipole moment that is created in this chemical bond is contradictory and is an interesting moment in chemical reactions.