Suspension

Definition

A suspension is a heterogeneous mixture in which particles of a finely divided solid substance are dispersed throughout a liquid or gas medium. The particles in a suspension are large enough to be visible to the naked eye and do not dissolve in the medium.

5 Must Know Facts For Your Next Test

1. Suspensions are heterogeneous mixtures, meaning the components are not uniformly distributed throughout the medium.
2. The particles in a suspension are large enough to be visible to the naked eye, unlike in a solution where the solute particles are too small to be seen.
3. Suspensions are not stable and the particles will eventually settle out, a process known as sedimentation.
4. Brownian motion helps keep the particles in a suspension dispersed and prevents them from settling out quickly.
5. The stability of a suspension can be improved by adding emulsifiers or surfactants, which help keep the particles evenly distributed.

Review Questions

• Explain the key differences between a suspension and a solution.
  • The main difference between a suspension and a solution is the size of the dispersed particles. In a suspension, the particles are large enough to be visible to the naked eye and do not dissolve in the medium, whereas in a solution, the solute particles are much smaller and are evenly distributed throughout the solvent, forming a homogeneous mixture. Additionally, suspensions are heterogeneous and the particles will eventually settle out, while solutions are homogeneous and the solute remains evenly distributed.
• Describe the role of Brownian motion in the stability of suspensions.
  • Brownian motion is the random movement of particles suspended in a fluid due to their collision with the fast-moving molecules in the fluid. This motion helps keep the particles in a suspension dispersed and prevents them from settling out quickly. Brownian motion counteracts the effects of gravity and sedimentation, allowing the particles to remain evenly distributed throughout the medium. This helps maintain the stability of the suspension and prevents the rapid separation of the solid and liquid components.
• Analyze how the addition of emulsifiers or surfactants can improve the stability of a suspension.
  • Emulsifiers and surfactants are added to suspensions to improve their stability by helping to keep the particles evenly distributed throughout the medium. These additives work by adsorbing onto the surface of the suspended particles, creating a barrier that prevents them from coming together and settling out. This barrier also helps to counteract the effects of gravity and sedimentation, allowing the suspension to remain more stable over time. The improved stability of the suspension is due to the emulsifiers or surfactants reducing the interfacial tension between the solid particles and the liquid medium, which in turn reduces the tendency of the particles to aggregate and settle.

Related terms

Colloid: A colloid is a heterogeneous mixture in which the dispersed particles are intermediate in size between those in a solution and those in a suspension, and are not easily filtered or separated.

Sedimentation: Sedimentation is the process by which particles in a suspension settle out of the medium and form a sediment at the bottom of the container.

Brownian Motion: Brownian motion is the random movement of particles suspended in a fluid due to their collision with the fast-moving molecules in the fluid.