U4.1b Physical Properties and Trends

Question 1

Volatility and Solubility of: Alcohols

Answer 1

Volatility: OH- that hydrogen bond gives higher IMF/BP therefore less volatile

Solubility: OH- group is polar and can from hydrogen bonds with water molecules. High solubility in water but decreases as chain size increases

Question 2

Volatility and Solubility of: Aldehydes

Answer 2

Volatility: Dipole Dipole interaction due to carbonyl (C=O) polarity. Low BP= high volatility.
Larger aldehydes are less volatile than smaller ones.

Solubility: Polarity of C=O increases interaction to create H+ bonding with water and therefore high solubility. Solubility decreases as chain length increases

Question 3

Volatility and Solubility of: Ketones

Answer 3

Volatility: C=O polarity with dipole dipole forces (weak IMF) interacting with ketone molecules result in low BP and more volatility as it is weaker than H+ bonding. Increasing weight decreases volatility

Solubility: Polarity of C=O increases interaction to create H+ bonding with water and therefore high solubility. Solubility decreases as chain length increases

Question 4

Volatility and Solubility of: Carboxylic Acids

Answer 4

Volatility: Carboxyl group (-COOH) that can form strong hydrogen bonds. Significantly high BPs therefore low volatility

Solubility: High solubility with small molecules due to effective H+ bonding of -COOH with water. Solubility decreases as chain length increases

Question 5

Volatility and Solubility of: Halides

Answer 5

Volatility: Halides tend to have boiling points that increase with molecular weight and size of the halogen. Generally less volatile
fluoroalkanes < chloroalkanes < bromoalkanes < iodoalkanes

Solubility: Organic halides generally less soluble in water. Smaller halides may exhibit some solubility due to dipole-dipole interactions. Solubility decreases as chain length increases