A. Solubility Observations Alcobol 10 drops added 20 drops added Ethy1 alcohol/
ID: 550444 • Letter: A
Question
A. Solubility Observations Alcobol 10 drops added 20 drops added Ethy1 alcohol/ ethanol n-butyl alcohoW 1-butanol butyl alcohol/2-methy -2-propenol n-bexyl aleohol 1-hexanol Glycerol 1,23-propanetriol 2. Explain any trends you observe: B. Freezing Points of aleohol isomers Compare the freezing points of n-butyl aloohol and +-butyl akcohol C. Tests for Primary, Secondary, and Tertiary Aleohols I. Chromic acid test Aleohol Methyl alcoholl methanol sec-butyl alcohol 2-butanol fert-butyl alcohol/ 2-methy-2-propanol Color after shaking Positive or segat tive test What classes of alcohol reacts with this test? Page |40 12Explanation / Answer
A)
Ethanol C2H5OH Soluble in water
1-butanol C4H9OH Partially soluble in water
Tert-butanol (CH3)3COH Almost miscible with water
1-Hexanol CH3 (CH2)5OH partially soluble in water
Propane-1,2,3-triol CH2OH-CHOH-CH2OH. Soluble in water
Solubility of alcohol in water depends on the structure of alcohol. Each alcohol consists of a carbon chain, which is nonpolar and OH group which is polar. Water is polar molecule, so it attracts OH group but carbon chain is nonpolar which repelled it. Solubility of alcohols is therefore determined by the stronger of the two forces. Due to the strength of the attraction of the OH group, first three alcohols (methanol, ethanol and propanol) are completely miscible with water. They dissolve in water in any amount. Starting with the four-carbon butanol the solubility of alcohols is starting to decrease. After the 7-carbon heptanol alcohols are immiscible with water.
Branched chain compounds are more soluble than corresponding straight chain isomers, so Tert-butyl alcohol is more soluble in water than than1-butanol. Glycerol has three hydroxyl groups, so it is soluble in water.
B) Freezing point of tert-butanol is 25.5°C. 1-butanol freezes at lower temperature at -89.8 °C. In tert-butanol a hydroxyl group is attached to a saturated carbon atom (CH3)3COH, so it has higher melting point.
c) Chromic acid test
Methanol Color after shaking blue-green positive test
2- Butanol Color after shaking blue-green positive test
Tert- butyl alcohol Color after shaking (chromic acid is orange, no change in color.) negative test.