Experiment 10

1. Experiment 10 sOLUBILITY Group 6 Ken Caceres Christian Daroya Rubycor Duran JomariGalecio JessaPilorin BSBIO1A

2. Objectives: • To define solubility • To identify the factors affecting it • To use the solubility class diagram competently Go to TEST COMPOUNDS

3. Solubility • It describes the amount of one substance (solute) that will dissolve in a specified amount of another substance (solvent) under stated conditions

4. Solute  -  A minor component of a solution. • Solution  -  A homogeneous mixture. • Solvent  -  The major component of a solution.

5. Soluble – that can be dissolved • Ex. Ethanol and water • Insoluble – cannot be dissolved • Slightly soluble -  A very small amount will dissolve and the solution will be transparent  • ex. Pentane and water

6. Solubility • Phenomenon: Like dissolves like • Polar solute dissolves polar solvent Ex. NaCl is soluble in water • Nonpolar solute dissolves nonpolar solvent • Ex. Pentane and benzene Factors • Van der Waals forces • Dipole forces between polar molecules • Hydrogen bonding • Branching in some compounds • Functional groups

7. 1. Van der Waals Forces (VWF) • These are forces between 2 nonpolar compounds • Non-polar liquids dissolve to each other because of VWF

8. 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.

9. 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

10. 3. H Bonding • these occur between polar covalent molecules that possess a hydrogen bonded to an extremely electronegative element, specifically - N, O, and F

11. 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 Legend: = Hydrogen bond = Oxygen = Hydrogen

12. 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

13. Branching in some compounds favors solubility in water • Because branched carbon chains will not allow close approach of the branched molecules • Thus leading to a decreased VWF and an increased H bonding

14. Functional groups • Solubility in water indicates the presence of OH group • Solubility 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.

15. Solubility Class of Organic Compounds • = determines the possible functional group classes to which the unknown may belong

16. 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:

17. A1 A2 • Higher molecular weight carboxylic acids fall into this class. • Strong acids • Phenols show this kind of solubility. • Weak acids SOLUBILITY TEST ANALYSIS:

18. 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. SOLUBILITY TEST ANALYSIS:

19. 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:

20. Test Compounds N-propyl alcohol Naphthalene Aniline Urea Benzoic Acid

21. Urea

22. Urea

25. Benzoic acid

27. 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.

28. Benzoic acid and Ether • Soluble • Benzoic acid is soluble in ether due to the low polarity of its molecules and weak intermolecular forces.

29. Benzoic acid and NaOH • Soluble • NaOH 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+

30. Benzoic Acid and NaHCO3 • soluble • NaHCO3 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

31. Benzoic Acid and HCl • Insoluble • HCl cannot dissolve benzoic acid because it is a nonpolar compound. • Benzoic acid can’t loose a proton (H+) just like HCl

32. Benzoic Acid and H2SO4 • Insoluble • H2SO4 cannot dissolve benzoic acid because it is a nonpolar compound. • Benzoic acid can’t loose a proton (H+) just like H2SO4.

33. Benzoic Acid and H3PO4 • Insoluble • H3PO4 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