Glycerol Structure, Characteristics: 23 Complete Quick Facts


Glycerol is the poly compound or polyol means it consists of one or more hydroxyl groups in it. Here, we are learning about Glycerol structure and its characterization.

Glycerol has empirical or chemical formula C3H8O3. The structural formula for glycerol is C3H5(OH)3. It can also be written as CH2OH-CHOH-CH2OH. Glycerol has the synonyms like glycerine and 1,2,3-propanetriol. Glycerol is a viscous liquid with no colour and odour, but it is quite sweet in taste. It is a non- toxic compound at low concentrations.

The glycerol structure is composed of mainly three elements i.e. carbon, hydrogen and oxygen. It has a hydrocarbon chain of three carbon atoms i.e. propane in which the three hydrogen atoms get replaced with three hydroxyl groups. All the three central C atoms have sp3 conformation and hence the glycerol molecule has free rotation over all bonds.

Glycerol is a triol compound that means it has three hydroxyl groups. It is much hygroscopic in nature and also soluble in water. It is capable of forming hydrogen bonds in water. The hygroscopic and water soluble nature of glycerol is due to presence of these three hydroxyl groups.

What is structure of glycerol?

Glycerol structure is mainly composed of three elements i.e. three carbon atoms, three hydrogen atoms and three hydroxyl groups. Due to the presence of three hydroxyl groups it is known as triols. In glycerol there is hydrocarbon long chain consists of three carbon atoms in a straight line.

The middle carbon atom has one hydrogen atom and one hydroxyl group, another two carbon atoms has two hydrogen atoms and one hydroxyl group. Basically it is consists of a propane molecule in which the three hydrogen atoms get replaced by three hydroxyl groups.

Glycerol structure

How to draw Glycerol lewis structure?

Lewis structure drawing is done by following some rules. Firstly check the periodic group positions of all C, H and O atoms present in the glycerol structure, as they are present in 14th, 1st and 16th groups of the periodic table. Then count the total valence electrons present in the glycerol structure by adding the valence electrons of all the elements.

Place the atom at central position of the structure which has lowest electronegativity. Hydrogen cannot take central position due to low valence, so carbon is less electronegative (2.55) than oxygen (3.44). Thus three carbon atoms are at the central position of the glycerol structure. Now, as per the total valence electrons make the bonding with all the outer bonding atoms i.e. hydrogen atoms and hydroxyl groups.

The valence electrons which form bonds are being bond pair electrons and the remaining electrons get put on the outer bonding H and OH groups. Now, count the lone electron present on each bonding atoms, also check whether the octet is complete or not of all the atoms. Finally count the formal charge present on the glycerol molecule and also verify its structure, hybridization and bond angle.

Glycerol valence electrons

Glycerol structure consists of three elements i.e. C, H and O which belong to the 14th, 1st and 16th group of periodic table. Thus, C atom has 4 valence electrons, H atom has 1 valence electrons and O atom has 6 valence electrons in their outer shell orbital. Let us calculate the valence electrons of glycerol structure.

Valence electrons of C atom of glycerol = 04 x 03 (C) = 12

Valence electrons of H atom of glycerol = 01 x 08 (H) = 8

Valence electrons on O atoms of glycerol = 06 x 03 (O) = 18

Total valence electrons on glycerol structure = 12 (c) + 08 (H) + 18 (O) = 38

Thus, glycerol structure has total thirty eight valence electrons present in it.

Let us calculate the total electron pairs present on glycerol molecule, for that we have to divide total valence electrons by 2.

Total electron pairs on glycerol structure = 38 / 2 = 19

Therefore, total 19 electron pairs present on glycerol structure.

glycerol structure
Valence electrons in Glycerol structure

Glycerol lewis structure octet rule

In glycerol structure, there are single covalent bonds between three carbon and hydrogen atoms (C-H) forming three C-H covalent bonds. Similarly, there is formation of covalent bonds between three C and three OH groups. Here, hydrogen atom cannot take more than two electrons in its valence shell orbital as it is belongs to 1st group having one valence electron.

Three central Carbon atoms has four valence electrons which they get shared with five hydrogen atoms and three oxygen atoms of three OH groups which has six valence electrons.Thus, all the three central carbon atoms of glycerol structure has complete octet as they have eight electrons which are four bond pair electrons forming C-H and C-OH bonds.

Similarly, each hydrogen atom also has satisfied its valency by having two bonding electrons forming C-H and O-H single covalent bonds. At last, the three oxygen atoms of glycerol also has complete octet as they have eight electrons present on it i.e. two C-H and O-H bond pairs and two non- bonding electron pairs. Hence, all the three C and O atoms of glycerol structure has complete octet.

Glycerol structure showing complete octet of C and O atoms

Glycerol lewis structure lone pairs

Out of total thirty eight valence electrons of glycerol structure, twenty six electrons are engaged in bonding. Now, we are left with more twelve valence electrons. These remaining twelve valence electrons should put on three oxygen atoms. Each oxygen atom can occupy more four electrons, which are being non- bonding electrons.

Therefore, the glycerol structure has total twelve non- bonding electrons on three oxygen atoms of glycerol. These twelve non- bonding electrons are being lone electron pairs of glycerol structure. However, there are total six lone electron pairs are present on three oxygen atoms of glycerol and thus the glycerol structure has total six lone electron pairs present on it.

Lone electron pairs on glycerol structure

Glycerol lewis structure formal charge

Any lewis structure is being much stable when there is quite little formal charge is present on the atoms of structure. Formal charge calculation can be done with the given following formula.

Formal charge = (valence electrons – non-bonding electrons – ½ bonding electrons)

While calculating the formal charge on glycerol structure, we have to calculate the formal charge formed on each atom or element of the glycerol structure. So, first we have to calculate the formal charge present on C, H and O atoms.

Carbon atom: Valence electrons on C atom of glycerol = 04

                       Non- bonding electrons on C atom of glycerol = 00

                       Bonding electrons on C atoms of glycerol = 08

Formal charge on C atom of glycerol structure is = (4 – 0 – 8/2) = 0

Thus, formal charge present on carbon atom of glycerol structure is zero.

Hydrogen atom:Valence electrons on H atom of glycerol = 01

                          Non- bonding electrons on H atom of glycerol = 00

                          Bonding electrons on H atom of glycerol = 02

Formal charge on H atom of glycerol structure is = (01 – 00 – 2/2) = 0

Thus, formal charge present on hydrogen atom of glycerol structure is zero.

Oxygen atom: Valence electrons on O atom of glycerol = 06

                       Non- bonding electrons on O atom of glycerol is = 04

                       Bonding electrons on O atom of glycerol is = 04

Formal charge on oxygen atom of glycerol structure is = (6 – 4 – 4/2) = 0

Thus, formal charge present on oxygen atom of glycerol structure is zero.

Therefore, the glycerol structure has complete formal charge present on C, H and O atoms are zero.

Formal charge on glycerol structure

Glycerol lewis structure resonance

In glycerol structure, there is only single covalent bonds are present all over the structure. Also the formal charge on glycerol structure is zero. Just two lone electron pairs are present on O atoms of glycerol molecule but they are not movable to form more multiple bonds in the structure as all the atoms have complete octet with sufficient electrons. Thus, resonance structure of glycerol molecule is not possible as it is not satisfied all the conditions of forming resonance structure.

Glycerol lewis structure shape

Glycerol structure has three central carbon atoms; the middle carbon atom gets attached with two carbon atoms, one oxygen atom and one hydrogen atoms. The other two side carbon atoms get attached with one carbon atom, one oxygen atoms and two hydrogen atoms. Thus all the three central carbon atoms get attached with four bonding atoms.

The glycerol structure also follows AX4 generic formula as all the three C atoms joined with four bonding atoms. Here, A = central atom and X = bonding atoms attached to central atom. So, the glycerol structure has tetrahedral molecular shape and electron geometry.

Tetrahedral shape of Glycerol structure

Glycerol hybridization

According to VSEPR theory the glycerol molecule has AX4 generic formula, as all the three central C atoms get attached with four bonding atoms. Thus glycerol structure has tetrahedral molecular shape and electron geometry. Hence, as per the VSEPR theory all the central carbon atoms are sp3 hybridized. Therefore, the glycerol molecule has sp3 hybridization as per VSEPR theory.

Glycerol lewis structure angle

The middle C atom has C-C-O and C-C-H bond angle of 109.5 degree. Also, the other two carbon atoms have H-C-H bond angles of 109.5 degree. But the H-C-O bonds of both the side carbon atoms could be bent due to repulsion causing by presence of lone electron pairs on O atoms.

Thus, H-C-O bond angle of glycerol molecule could be bent and may be having 103.5 degree bond angles. Hence, glycerol structure has 109.5 degree and 103.5 degree bond angles.

Glycerol solubility

Glycerol is soluble in:

  • Water
  • Alkenols (R-OH)
  • Ethanol
  • Ethyl acetate (partially soluble)
  • Acetone (partially soluble)
  • Ethyl ether (partially soluble)

Glycerol is insoluble in:

  • Chloroform
  • Carbon disulphides
  • Benzene
  • Oils
  • Carbon tetrachloride
  • Petroleum ether
  • Fixed and volatile oils

Is Glycerol soluble in water?

Yes, glycerol is easily soluble in water. The solubility rule ‘Like dissolves like’ could apply on glycerol water solubility. Because both water and glycerol containing hydroxyl (OH) groups so they can easily soluble or miscible with each other.

Why glycerol is soluble in water?

Glycerol contains three hydroxyl (OH) groups due to which it becomes much viscous in nature. Also it is quite hygroscopic in nature as it can absorb moisture from atmosphere or air. As more it absorbs the moisture from atmosphere, glycerol becomes less viscous in nature. As the glycerol is more viscous less it soluble in water and as glycerol is less viscous more it soluble in water.

Also the glycerol contains polyol groups i.e. glycerol contains more hydroxyl groups than water. The glycerol contains three hydroxyl groups and the water contains one hydroxyl group thus glycerol can form more hydrogen bonds with water and hence it is easily soluble in water.

How glycerol is soluble in water?

When glycerol is added to water, it first get settle down at the bottom of the container because the glycerol is much denser in nature than water and having specific gravity1.26. But as the glycerol get more soluble over time in water by stirring or heating the solution. So, all the undissolved glycerol gets soluble in water.

Also glycerine or glycerol is a trihydric quite big alkanol molecule. Glycerol has three hydroxyl (OH) groups joined to three carbon atoms. These three hydroxyl groups are hydrophilic regions and are polarized in nature. Thus these three hydroxyl groups of glycerol makes the solubility process easy with water molecules which also contains polarized hydroxyl (OH) group.

Hydrogen bonding between glycerol and water

Is Glycerol a strong electrolyte?

Glycerol is not a strong electrolyte. Glycerol is basically a non- electrolyte. Electrolyte is a substance which when dissolves in water can generate mobile ions which permit the water for electricity conduction. The compounds which cannot generate mobile ions when mixed in water and cannot permit the water to conduct electricity are non- electrolytes. Here, glycerol play a role of non- electrolyte.

Why glycerol is non- electrolyte?

In terms of covalent compounds, the covalent compounds get reacts with water in another way to work as electrolyte. When covalent acids react with water it donates the protons (H+) ions to water to produces ions in water. Similarly when covalent bases react with water it accepts protons from water to produce ions in water.

The glycerol compound is also a covalent compound as it has the single covalent bonds all over its structure. Still glycerol is non- electrolyte because when glycerol mixed with water it cannot form ions in water solution. But it can form hydrogen bonds with water molecules and being a neutral or non- electrolytic in nature. Thus, Glycerol is non- electrolyte.

How glycerol is non- electrolyte?

There are three kinds of electrolytes i.e. strong electrolyte, weak electrolytes and non- electrolytes. Strong electrolytes are those compounds which are strong conductors of electricity as they can form huge number of mobile ions. Rather, weak electrolytes are those compounds which are weak conductors of electricity as they can form small number of mobile ions.

Non- electrolytes are those compounds which are non- conductors of electricity as they cannot form mobile ions in water solution. Thus the glycerol is the compound which is not a good conductor of electricity and cannot produce mobile ions when mixed with water. Hence, glycerol is a non- electrolytic in nature.

Is Glycerol acidic or basic?

Glycerol is nor acidic neither basic in nature. Rather basically it is a neutral compound. But the glycerol in pure form behaves as a weak acid. Glycerol is an alkanol (R-OH) containing hydroxyl (-OH) group. The glycerol molecule has pH value nearly 7.3 which shows the neutrality of glycerol. Hence, glycerol is considered as a neutral compound.

Why glycerol is neutral?

Glycerol is an hydrocarbon containing hydroxyl (OH) groups which cannot get separated into ions. Pure form of glycerol when reacts with water it quite acts as a weak acid like methanol. But even if glycerol contains three hydroxyl (OH-) ions, still it is not acts like a base.

Glycerol molecule contains three hydroxyl (OH) groups in its structure, still this three hydroxyl (OH) groups cannot divides as ions. It is basically an alkanol (R-OH) to which three OH groups joined to three C atoms.

Even at higher pH values like 12 or 13 the hydrogen atom of hydroxyl ion of glycerol can somewhat dissociates forming a charged ion or species. This can somewhat increases the solubility but still the uncharged compounds solubility is infinite and no change formed in its solubility.

How glycerol is neutral?

Glycerol cannot form salts when reacts with acids but it can form esters known as triglycerides. In water solution it depends on concentration of water and glycerol which is slightly less than 7. Pure form of glycerol has pH value more than 7. pH is generally determines the H+ ions (hydrogen cations) concentration in water solution but not for pure form of compounds.

Pure form of glycerol can behaves as a very weak acid because it is quite difficult to separate hydrogen from OH groups. Even difficult to separate H+ ion from water too. Thus H+ ions cannot be stable with water and pure glycerol reaction. Thus H+ ion concentration is very less in pure glycerol. Hence it is a neutral or very weak acid in nature.

Is Glycerol polar or nonpolar?

Yes glycerol is a polar molecule. As we seen it is easily soluble in water which is a polar molecule. Thus polar polar molecules get dissolves with each other. Hence, glycerol molecule is also polar in nature.

Why Glycerol is polar?

Glycerol is polar molecule. Even the polarity of glycerol molecule cancel out somewhat, still it is polar molecule because of the presence of three carbon oxygen (C-O) bonds. These three C-O bonds of glycerol are polar bonds. Hence, glycerol molecule behaves as polar in nature.

How Glycerol is polar?

Glycerol molecule contains three OH groups, thus polar in nature. In polar molecules there is a separation of electric charge, also it contains a polar bond. The polar molecule which contains more than one polar bond have asymmetric geometry, thus the bond dipoles cancels out each other.

Also the polar bonds are caused due to the electronegativity difference between the bonded atoms. Polar molecule reacts with each other by hydrogen bonds and dipole- dipole intermolecular forces. The net dipoles are present on polar molecules due to the presence of opposite charged ions. Hence, there are three C-O polar bonds in glycerol due to which it becomes polar in nature.

Is Glycerol paramagnetic or diamagnetic?

Yes, glycerol is diamagnetic in nature. All the electrons are paired in the structure of glycerol molecule, so it should be considered as diamagnetic molecule. The magnetic susceptibility value of glycerol is -57.06·10−6 cm3/mol.  

Why glycerol is diamagnetic?

Glycerol is diamagnetic in nature. The magnetic compounds which are aligning opposite way to magnetic field are known as diamagnetic compounds. Magnetic susceptibility value for diamagnetic compounds is always a negative value and which is less than zero (x<0).

These compounds are repelled with magnetic field and moves from stronger magnetic field to a weak magnetic field. They are temperature independent. As these compounds magnetized in opposite way, they have very tiny amount of magnetic intensity. These compounds have persistent relative permeability.

How glycerol is diamagnetic?

The magnetism is determined by presence of paired and unpaired electrons in the compound, and also determined with the application of outer magnetic field and movement of the compound towards or opposite direction of magnetic field. Also it is determined by calculating magnetic susceptibility value of that compound.

If the compound has paired electrons then it is diamagnetic. So, the glycerol structure has all the paired electrons in its structure. Hence glycerol is a diamagnetic compound. Also it get moves in opposite direction of magnetic field i.e. moves towards weak magnetic field. Glycerol has negative susceptibility value -57.06·10−6 cm3/mol which is less than zero. Thus glycerol is a diamagnetic compound.

Glycerol viscosity

Glycerol is highly viscous in nature. The ability of the liquid to move or flow is known as viscosity of that compound. The highly viscous fluids or liquids like glycerol can move or flow very slowly.

Why glycerol is viscous?

Viscosity is the ability of the liquid substance to flow. Glycerol is a highly viscous compound as it consists of three hydroxyl (OH) groups and thus it can form more hydrogen bonds. Due to this reason glycerol molecules are highly connected, so glycerol is highly viscous in nature.

How glycerol is viscous?

Glycerol molecule is highly viscous as it has three hydroxyl groups. So, they have greater intermolecular forces due to formation of more hydrogen bonds. Viscosity is also determined by intermolecular forces strength and the shape of the liquid compounds. The polar liquids which can form hydrogen bonds are generally highly viscous.

Also the long chain liquid compounds are more viscous. Glycerol is three carbon chain containing compound CH2OH-CHOH-CH2OH thus it is partly viscous as the length of C chain is not so long but can more viscous due to it ability of forming hydrogen bonds.

Is glycerol a lipid?

Glycerol is not a lipid but it is an alkoxy (R-OH) compound as it contains OH groups in it. Lipids are the substance which comes under macromolecules including steroids, fats and phospholipids. Glycerol is an an alcoholic compound having three OH groups attached to three carbon atoms.

Why glycerol is not a lipid?

Lipids are very long chain macromolecule compounds. Glycerol molecule contains a small carbon chain having only three C atoms in its structure. Glycerol can produce lipids by dehydration reaction with fatty acids but originally glycerol is not a lipid rather it is an alkoxy compound.

How glycerol is not lipid?

Glycerol is a triol containing three OH groups. It is a sugar alkanol so it can consider as carbohydrates also. But glycerol is not a lipid rather glycerol is the main constituent or backbone in the formation of lipids. It can form easter bonds with glycerol and fatty acids known as glycerides. Many complex lipids are produced with combining hydrophobic and hydrophilic compounds like glycerol and fatty acids.

Is glycerol lipid soluble?

No, glycerol and lipids are not soluble with each other as they both have opposite properties. Glycerol is a polar molecule and lipids are non- polar in nature. Thus they both are insoluble with each other.

Why glycerol is not lipid soluble?

Glycerol is the important constituent in lipid formation. But glycerol is unable to soluble in lipids. Lipids are long carbon chain compounds and glycerol is short chain carbon compounds. Hence, they both are not soluble with each other due to difference in carbon chain lengths of both compounds. As glycerol is polar molecule it is being soluble in polar compounds only.

How glycerol is not lipid soluble?

Generally glycerol is a polar compound and soluble only in polar molecules only. Lipids are non- polar compounds but some lipids like phospholipids shows both polar and non- polar nature due to presence of phosphate ion it is partially water soluble too. But triglycerides are totally non- polar. So the polar glycerol is not soluble in non-polar triglycerides.

Is glycerol hydrophobic?

No, glycerol is not hydrophobic rather it is hydrophilic in nature as it is soluble in water. Hydrophilic means water loving, due to solubility in water it is hydrophilic and not hydrophobic.

Why glycerol is hydrophilic?

Glycerol molecule contains three OH groups in its structure. Thus when it gets mixed with water it is able to form more hydrogen bonds with water molecules and hence it is hydrophilic.

How glycerol is hydrophilic?

The glycerol has three OH groups and showing polar nature, water is also polar molecule thus they both are soluble with each other. O atom of glycerol has lone pair electrons which it get shared with hydrogen atom of water to form hydrogen bond within them. So, glycerol is water loving and thus hydrophilic molecule.

Is glycerol glycerine?

Glycerol and glycerine is quite different compounds as they are being used in different ways. Still they are considered to be same generally.

Why glycerol and glycerine is different?

Production of glycerol needed glycerine. Glycerin is commercial compound and used as a main component to form glycerol. Glycerol and glycerine is generally used in similar ways. Glycerin is an polyol compound which is used as sweetner and preservative. Also it is a thick gummy substance on being frozen. Hence, both are different.

How glycerol and glycerine is different?

Glycerol is fats component which is colourless and add sweet taste as used as wine making process. It is a natural sweetner and used as solvent, preservative and thickening agent. It is used as cough syrups and body creams while glycerine used in toothpaste. Thus both are different.

Is glycerol soluble in hexane?

No, glycerol and hexane is not miscible with each other. Both are opposite solutions in nature i.e. polar and non- polar and thus are not possible to mix with each other.

Why glycerol is not soluble in hexane?

Glycerol is a polar molecule having three OH groups present on three C atoms and hexane is a non-polar molecule having long carbon chain of six carbon atoms and no OH group is present in it. Thus they both are insoluble with each other.

How glycerol is not soluble in hexane?

Polar compounds with small C chain can dissolve with the polar compounds only, as the C chain increases the compound being non polar in nature. Thus, hexane having long carbon chain and glycerol has small carbon chain with only three C atoms and there is no exchange of ions and thus they are not soluble with each other.

Conclusion:

Glycerol is a alkanol compound with three OH groups attached to three C atoms. It has no odour, no colour but sweet in taste. It has 38 valence electrons and forming single covalent bonds and have no formal charge and six lone electron pairs are present on it. It is polar molecule, soluble in water and viscous in nature. It has tetrahedral shape, sp3 hybridization and 109.5 and 103.5 degree bond angles.

Dr. Shruti Ramteke

Hello everyone I am Dr. Shruti M Ramteke, i did my Ph.D in chemistry. I have five years of teaching experience for 11-12 standard, B,Sc and MSc in chemistry subject. I have published total five research articles during Ph.D on my research work and i have fellowship from UGC for my Ph.D. My Masters with specilization Inorganic chemistry and my graduation with chemistry, zoology and environmental science subjects. thank You

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