Question

Difficulty: MediumTypes of Solutions: True Solutions, Suspensions, and Colloidal Systems

A laboratory technician prepares a mixture by thoroughly stirring gelatin in warm water. The resulting mixture passes completely through standard filter paper without leaving any solid residue, but when a concentrated beam of light passes through it in a darkened box, the path of the light beam becomes illuminated and visible. Which type of mixture is represented by this system?

A colloidal systemAnswer
B
A true solution
C
A suspension
D
A coarse sediment

Answer

A colloidal system

Gelatin dispersed in warm water is a colloidal system. Colloidal particles range in diameter from

1\text{ nm}

to

100\text{ nm}

. This particle size is small enough to pass through standard filter paper pores, but large enough to scatter visible light rays (Tyndall effect).

Step-by-Step Solution

1

Analyze the filtration behavior described in the stem.

The mixture passes through standard filter paper without leaving a residue.

This eliminates suspensions, which have particle diameters exceeding

100\text{ nm}

and get trapped by filter paper pores.

2

Analyze the optical behavior (light scattering) described in the stem.

The mixture demonstrates the Tyndall effect by illuminating the light path.

True solutions have solute particles smaller than

1\text{ nm}

that cannot scatter visible light, whereas colloidal particles (

1\text{ nm}

to

100\text{ nm}

) effectively scatter light.

3

Synthesize the particle size characteristics to identify the mixture class.

The mixture is a colloidal system.

Exhibiting light scattering while passing through filter paper is the hallmark property distinguishing colloidal systems from true solutions and suspensions.

Key Concept

Distinguishing characteristics of true solutions, colloidal systems, and suspensions based on particle size and Tyndall effect.

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Topics

Types of Solutions: True Solutions, Suspensions, and Colloidal Systems