A student carefully pours 10 mL of hexane (density 0.66 g mL⁻¹) into 10 mL of liquid…
CHEMISTRY · Single correct · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
A student carefully pours 10 mL of hexane (density 0.66 g mL⁻¹) into 10 mL of liquid water (density 1.00 g mL⁻¹) contained in a beaker and stirs briefly. After settling, two clear layers are observed, with the upper layer colorless and the lower layer blue (the water was dyed). Which statement best accounts for both the formation and the relative positions of the layers?
(a) The two layers form solely because hexane is less dense than water; density alone explains both formation and positioning.
(b) Hexane and water are immiscible owing to their different polarities; once separated, the less-dense hexane floats above the water.
(c) The separation would disappear with more vigorous or prolonged stirring; the current layering is due to insufficient mixing time, not chemical differences.
(d) Layering occurs because individual water molecules are heavier than individual hexane molecules, so the heavier water settles on the bottom regardless of polarity.