explain the similarities between alcohol molecules and water molecules

Physical Properties of Alcohols

The table on a lower floor gives just about of the physical properties of the archetypical four alcohols in the alcohol homologous series:

Name	Number of Atomic number 6 atoms	Building block Formula CnH2n+1OH	Structural Recipe	Boiling Stage °C	Solubility g per 100g of water
Wood alcohol	1	C1H2(1)+1OH = CH2+1OH = CH3OH		64	infinite
Ethanol	2	C2H2(2)+1OH = C2H4+1OH = C2H5OH		78	multitudinous
Propanol	3	C3H2(3)+1OH = C3H6+1Buckeye State = C3H7OH		98	infinite
Butyl alcohol	4	C4H2(4)+1Buckeye State = C4H8+1OH = C4H9OH		118	8.0

The intermolecular forces between the molecules of a compound are a determining broker in its physical properties. Intermolecular forces in compounds arise imputable an imbalance of blame. In the alkanes section we discussed the effects of Johannes Diderik van der Waals' intermolecular forces of attracter on the physical properties and that the strength of these forces increased with the sizing of the speck.

Alcohols, like alkanes, have Van der Waals' building block attractive forces. But, they as wel have an additional unit force of attractiveness receivable to the presence of the hydroxyl group (O—H) called atomic number 1 bonding.

Hydrogen Soldering in Alcohols

Hydrogen soldering is caused by the power of particular atoms to strongly pull in the electrons in a bond. A measure of how strongly an atom in a rough attracts electrons in a bond is called electronegativity. Hydrogen bonds are formed when a hydrogen atom is covalently bonded to unrivalled of the electronegative atoms, fluorine, Cl, oxygen Beaver State nitrogen.

In alcohols the hydrogen bond is formed imputable the covalent bonds between unrivalled oxygen atom and one hydrogen atom in the hydroxyl group (O—H). Atomic number 8 is a highly negative mote and attracts the electrons in the O—H bonds towards itself. Since the proton in the nucleus of the H atom is only slightly screened the action of the oxygen pulling the electrons away from the hydrogen results in a sack up positive charge on the H atom. Consequently there is besides a internet unfavorable charge on the oxygen atom resulting in an imbalance of direction across the hydroxyl aggroup. The overall hydroxyl group grouping is said to be polar because wish a magnet it has two opposite charges on either ends (its poles). The take-home positive atomic number 1 molecule is promptly available to attract the negative electron clouds from the oxygen atom in an adjacent hydroxyl radical. Unlike Caravan der Waals' forces, hydrogen bonding involves a permanent imbalance of shoot and therefore results in permanent dipole attractions.

The diagram below represents hydrogen bonding in ethanol molecules. Each fermentation alcohol molecule has 1 O—H bond and thus forms combined hydrogen bond with adjacent ethanol molecules.

Boil

The graph below shows a game of the stewing points of the first four alcohols and alkanes from their respective homological serial publication:

From the graph the following can be inferred:

• The boil of an alcohol is importantly high than that of an alkane with the same figure of carbon atoms.
• The boiling points of the alcohols increase with increasing number of carbon atoms.

The difference in the boiling points between alcohols and alkanes with the same number of carbon atoms can atomic number 4 explained by the following points:

1. Alcohols hold in the hydroxyl group (O—H) which produce intermolecular forces of attraction through atomic number 1 soldering. Hydrogen bonds are much stronger than Caravan Der Waals' unit forces. Alcohols contain deuce types of unit forces of attraction hydrogen bonding and Van der Waals.  In alkanes in that respect are merely Van Der Waal unit forces of attraction. The additional forces of attractive feature collectible to hydrogen bonding between the hydroxyl groups in adjacent molecules of an alcohol make their boiling points high than alkanes with the same keep down of carbon atoms.
2. When comparing alcohols to alkanes it mustiness also be remembered that for the same number of carbon atoms an alcohol is a larger corpuscle as one hydrogen from the paraffi is replaced with a hydroxyl. The oxygen atom in the hydroxyl radical contains eight electrons and this increases the overall Van Der Waals' intermolecular forces of attraction across the corpuscle. The large Van Der Waals' intermolecular forces old in an inebriant compared to an alkane of the similar number of C atoms is also a factor out the higher boiling point.

The reason for the growth in boiling point with increasing atomic number 6 atoms in the alcohol homogeneous series is similar thereto in the alkane homologous series. As the size and unit mass of the molecule increases sol does the phone number of electrons resulting in a greater imbalance in charge and hence a stronger Van der Waals' attraction. American Samoa the alcohol molecules get larger the influence of the hydroxyl chemical group becomes less compared to the increasingly large hydrocarbon portion. This also explains wherefore long straight chain inebriant molecules experience physical properties which tent towards the corresponding long chain alkane molecules.

Solubility of Alcohols

Solubility of alcohols falls with augmentative number of carbon atoms. The small chain alcohols are good solvents and miscible with water supply. Methanol, ethanol and propanol are completely soluble in water system altogether proportions. But as the enumerate of carbon atoms increases, solubility decreases.

Name	Number of Carbon atoms	Unit Formula CnH2n+1OH	Structural Formula	Solvability g per 100g of water
Methanol	1	C1H2(1)+1OH = CH2+1Buckeye State = CH3OH		infinite
Ethanol	2	C2H2(2)+1OH = C2H4+1OH = C2H5OH		infinite
Propanol	3	C3H2(3)+1OH = C3H6+1OH = C3H7Buckeye State		numberless
Butanol	4	C4H2(4)+1Buckeye State = C4H8+1OH = C4H9Buckeye State		8.0
Pentanol	5	C5H2(5)+1OH = C5H10+1OH = C5H11OH		2.6
Hexanol	6	C6H2(6)+1Buckeye State = C6H12+1OH = C6H13OH		0.9

The high-topped solubility of the small chain alcohols is payable to the hydroxyl (O—H) group. The hydroxyl radical is polar due to the imbalance in charge 'tween the oxygen and hydrogen atom. This allows the hydroxyl group in the inebriant molecule to interact with polar water molecules by forming hydrogen bonds.

The animation below shows the interaction 'tween ethanol and water molecules ready to excuse the solvability of small chain alcohols:

As the number of carbon atoms in the alcohol chain gets bigger the solubility in water decreases. This is because the long chain alcohols fork out between the water molecules and break the hydrogen bonds. However, the long chain molecules sole have one hydroxyl group to hydrogen bond with the water molecules compared to the numerous that have been displaced. This results in more of the original hydrogen bonds in the water molecule not being replaced. Therefore, the energy required in breaking the original hydrogen bonds is not granted back in the formation of spick-and-span bonds then energy considerations hold long chain alcohols less answerable.

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explain the similarities between alcohol molecules and water molecules

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