Learn on PengiAmplify Science (California) Grade 5Chapter 2: Why do some salad dressings have sediments, and others do not?

Session 3: Sediments and Suspensions

Key Idea.

Section 1

When Particles Don't Stick

Key Idea

Why doesn't everything dissolve? It comes down to attraction.

For a solid to dissolve, the liquid molecules have to pull the solid particles apart. But sometimes, the solid particles like each other more than they like the liquid. They clump together and refuse to separate. Because there is no attraction to pull them apart, they remain as visible clusters.

Section 2

Sinking to the Bottom

Key Idea

If the solid particles stay clustered, gravity eventually takes over. The heavy clumps sink to the bottom of the container.

This layer of settled solid is called sediment. You might see this in a bottle of orange juice where the pulp has settled at the bottom. Sediment is visual proof that the solid is insoluble in that liquid.

Section 3

The Temporary Mix: Suspension

Key Idea

If you shake a mixture of sand and water, it looks cloudy for a moment. The sand particles are floating around, but they are not dissolved.

This temporary mixture is called a suspension. It looks mixed for a short time, but because the particles are not attracted to the water, they will eventually settle out. A suspension is unstable; it will always separate back into liquid and sediment.

Lesson overview

Expand to review the lesson summary and core properties.

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Section 1

When Particles Don't Stick

Key Idea

Why doesn't everything dissolve? It comes down to attraction.

For a solid to dissolve, the liquid molecules have to pull the solid particles apart. But sometimes, the solid particles like each other more than they like the liquid. They clump together and refuse to separate. Because there is no attraction to pull them apart, they remain as visible clusters.

Section 2

Sinking to the Bottom

Key Idea

If the solid particles stay clustered, gravity eventually takes over. The heavy clumps sink to the bottom of the container.

This layer of settled solid is called sediment. You might see this in a bottle of orange juice where the pulp has settled at the bottom. Sediment is visual proof that the solid is insoluble in that liquid.

Section 3

The Temporary Mix: Suspension

Key Idea

If you shake a mixture of sand and water, it looks cloudy for a moment. The sand particles are floating around, but they are not dissolved.

This temporary mixture is called a suspension. It looks mixed for a short time, but because the particles are not attracted to the water, they will eventually settle out. A suspension is unstable; it will always separate back into liquid and sediment.