Question

A dictionary definition of homogeneous is "uniform in composition throughout." River water is a mixture of dissolved compounds, such as calcium bicarbonate, and suspended soil particles. Is river water homogeneous? Explain.

Short answer

No, river water is not homogeneous because it contains suspended particles that are not uniformly distributed.

Step-by-step solution

- Define Homogeneous

A substance is homogeneous if it is uniform in composition throughout. This means that the properties and composition are the same no matter where you sample the material.

- Analyze River Water Composition

River water contains dissolved compounds, such as calcium bicarbonate, and suspended soil particles. These components are distributed throughout the river water.

- Assess Uniformity

Consider the distribution of dissolved compounds and suspended soil particles in river water. While dissolved compounds are uniformly spread, suspended particles are not.

- Conclusion

Since the suspended soil particles are not uniformly distributed and can vary from one sample to another, river water does not have a uniform composition throughout. Therefore, river water is not homogeneous.

Key concepts

Composition Uniformity

When we talk about a material being homogeneous, we mean it must have a uniform composition throughout. This means every sample you take from a homogeneous mixture will have the same properties and composition.
Think about a glass of well-mixed saltwater. No matter where in that glass you take a sip, it will taste the same because the salt is completely dissolved and spread out evenly. This is an example of a homogeneous mixture.
On the other hand, if you consider a pile of mixed nuts, that's not homogeneous. Different parts of the pile will have different types of nuts. So, its composition isn't uniform throughout.

Dissolved Compounds

Dissolved compounds are substances that have been completely integrated into a solvent, becoming part of a homogeneous solution.
In the context of river water, compounds like calcium bicarbonate dissolve and uniformly distribute themselves in the water.
Because they are dissolved, you can't see them, and they do not settle to the bottom over time.
This uniform distribution of dissolved compounds is an important aspect of homogeneous mixtures.
However, for a solution to be considered homogeneous, all its components must be uniformly distributed.

Suspended Particles

Suspended particles are small solid fragments that float in a liquid but do not dissolve. In river water, these could be particles of soil or other substances that are carried along by the flowing water.
Unlike dissolved compounds, suspended particles are not uniformly distributed throughout the mixture.
They might settle at the bottom over time or vary in concentration from one part of the river to another.
Because of these suspended particles, river water does not have a uniform composition and is therefore not homogeneous.
It’s important to distinguish between dissolved substances and suspended particles when analyzing mixtures.