A chemist is comparing the behavior of two organic liquids—acetic acid (CH3COOH) and…
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
A chemist is comparing the behavior of two organic liquids—acetic acid (CH3COOH) and n-hexane (C6H14)—when each is added separately to liquid water at 25 °C and 1 atm. The chemist observes that one of the liquids mixes completely with water in all proportions, whereas the other forms a distinct second layer.
Answer the following questions about the contrasting solubilities of these two liquids in water.
(a) Identify which liquid is completely miscible with water and which forms a separate layer. Provide evidence from the molecular structures of the two liquids to support your identification.
(b) Describe, at the particulate level, the types of intermolecular forces that operate between molecules of the miscible liquid and water in the resulting homogeneous solution.
(c) Explain why the other liquid fails to mix with water, referring explicitly to polarity and intermolecular forces.
(d) Predict how adding a small amount of ethanol to the water–n-hexane mixture would influence the extent of mixing between n-hexane and the aqueous phase. Justify your prediction.