Experiment 10

Group 6Ken CaceresChristian DaroyaRubycor DuranJomari GalecioJessa Pilorin

SOLUBILITY

BSBIO1A

Objectives:

1. To define solubility2. To identify the factors affecting

it3. To use the solubility class

diagram competently

GO TO TEST COMPOUNDS

SolubilityIt describes the amount of one

substance (solute) that will dissolve in a specified amount of another substance (solvent) under stated conditions

Solute  -  A minor component of a solution.

Solution  -  A homogeneous mixture.

Solvent  -  The major component of a solution.

Soluble – that can be dissolvedEx. Ethanol and waterInsoluble – cannot be dissolvedSlightly soluble -  A very small

amount will dissolve and the solution will be transparent 

ex. Pentane and water

SolubilityPhenomenon: Like dissolves likePolar solute dissolves polar solvent Ex. NaCl is soluble in waterNonpolar solute dissolves nonpolar

solventEx. Pentane and benzeneFactors1. Van der Waals forces2. Dipole forces between polar molecules3. Hydrogen bonding4. Branching in some compounds5. Functional groups

1. Van der Waals Forces (VWF)

These are forces between 2 nonpolar compounds

Non-polar liquids dissolve to each other because of VWF

Ion-induced dipole attraction

a type of VWF which is a weak attraction that results when the approach of an ion induces a dipole in an atom or in a nonpolar molecule by disturbing the arrangement of electrons in the nonpolar species.

2. Dipole – dipole interaction

Forces between 2 polar compounds

Cause of polar liquid’s solubility to each other

Positive and negative ends attract each other

3. H Bondingthese occur

between polar covalent molecules that possess a hydrogen bonded to an extremely electronegative element, specifically - N, O, and F

Lower alcohols (low MW) are soluble in water because the attraction between the OH (hydroxyl group) of water and alcohol are similar to those between individual water / alcohol molecules

= Hydrogen bond

= Oxygen= Hydrogen

Legend:

Increase in carbon chain length, in high- molecular weight alcohols, decreased water solubility

This is because the strength of VWF increases with the increasing chain length

Branching in some compounds favors solubility in waterBecause branched carbon chains

will not allow close approach of the branched molecules

Thus leading to a decreased VWF and an increased H bonding

Functional groupsSolubility in water indicates the

presence of OH groupSolubility in a basic solvent

(NaHCO3) indicates the presence of an acidic functional group

Ex. Solubility of benzoic acid in NaHCO3 with –COOH (carboxyl group) as functional group.

Solubility Class of Organic Compounds

= determines the possible functional

group classes to which the

unknown may belong

SOLUBILITY TEST ANALYSIS:

S1 S2

These are very polar compounds which consist of salts of carboxylic acids or amines.

It is also possible the compound is of low molecular weight and has many polar functional groups such as a carbohydrate.

Low mol. Wt. (MW) amines

These compounds are low molecular weight (generally less than 5 carbons) with a polar functional group such as carboxylic acid, amine, alcohol, aldehyde, or ketone.

Low MW carboxylic acids

SOLUBILITY TEST ANALYSIS:

A1 A2

Higher molecular weight carboxylic acids fall into this class.

Strong acids

Phenols show this kind of solubility.

Weak acids

SOLUBILITY TEST ANALYSIS:

B1 N1

Primary, secondary and tertiary amines fall into this class.

However, if there are two or more phenyl groups on the nitrogen, the amine will probably not be basic enough to form the salt and will, then, be insoluble.

These are higher molecular weight compounds (generally more than 9 carbons) containing an oxygen atom.

N2 INERT

These are medium size molecules (generally containing from 5 to 9 carbons) containing an oxygen atom.

These are neutral compounds. Alkyl halides and alkanes fall into this class.

SOLUBILITY TEST ANALYSIS:

Test Compounds

N-propyl alcohol

Naphthalene

Urea

Aniline

Benzoic Acid

Urea

Molecular Formula

Structural Formula

Commonname

Properties

CO(NH2)2

Carbamide resin

Isourea

MW: 60.06g/mol

Appears as a white solid

MP:133-135°C

NH2

CNH2

O

Urea Distilled H2O soluble

Ether Insoluble

NaOH Soluble

NaHCO3 Soluble

HCl Soluble

H2SO4 Soluble

H3PO4 soluble

Solubility Class S2

Benzoic acid

IUPAC Name

CommonName

Molecular Formula

Structural Formula

Benzoic acid

Benzene-carboxylic acid

C7H6O2

Benzoic acid and distilled water

Insoluble to cold water but can be soluble to hot water

Water-solubility of carboxylic acids decrease as the number of carbons increase. In case of benzoic acid, the molecule contains seven carbons and six of them form a benzene ring.

Benzoic acid and Ether

SolubleBenzoic acid

is soluble in ether due to the low polarity of its molecules and weak intermolecular forces.

Benzoic acid and NaOHSolubleNaOH helps

deprotonate benzoic acid

organic acids (such as carboxylic acids) react with bases to form water soluble salts

Either strong/weak acid

R-COOH + Na+ + OH- + H2O → R-COO- Na+ + OH- + H3O+

Benzoic Acid and NaHCO3solubleNaHCO3 is a weak

base that reacts with organic acids to form water soluble salts

Solubility to NaHCO3 makes it a strong acid or Class A1

Benzoic Acid and HClInsolubleHCl cannot

dissolve benzoic acid because it is a nonpolar compound.

Benzoic acid can’t loose a proton (H+) just like HCl

Benzoic Acid and H2SO4InsolubleH2SO4 cannot

dissolve benzoic acid because it is a nonpolar compound.

Benzoic acid can’t loose a proton (H+) just like H2SO4.

Benzoic Acid and H3PO4InsolubleH3PO4 cannot

dissolve benzoic acid because it is a nonpolar compound.

Benzoic acid can’t loose a proton (H+) just like H3PO4

Back to Test Compounds