Classify each of the following as a pure substance or a mixture. If a mixture, indicate whether it is homogeneous or heterogeneous. Drag the appropriate items to their respective bins. baking soda tap water sawdust cola with ice Pure substance Homogeneous mixture Heterogeneous mixture
The Correct Answer and Explanation is:
Let’s classify the given substances:
- Baking Soda – Pure Substance
Baking soda (sodium bicarbonate, NaHCO₃) is a pure compound. It consists of only one type of molecule, so it is classified as a pure substance. Pure substances are elements or compounds that have a consistent composition and cannot be separated by physical means into other substances. - Tap Water – Homogeneous Mixture
Tap water is a mixture, but it is usually classified as homogeneous. This is because it typically contains dissolved substances such as salts, minerals, and gases (like oxygen and carbon dioxide), but the composition is uniform throughout. Even though tap water may contain impurities, it appears consistent to the naked eye, hence it is considered homogeneous. - Sawdust – Heterogeneous Mixture
Sawdust is a mixture made up of small pieces of wood. It is heterogeneous because the individual components (wood particles, air, moisture) can be easily distinguished or separated. The composition is not uniform throughout, as you can observe different-sized wood particles and variations in texture. - Cola with Ice – Heterogeneous Mixture
Cola with ice is also a heterogeneous mixture. The ice cubes are solid, and they remain separate from the liquid cola. As the ice melts, it may mix with the cola, but you can still observe the ice cubes, so the mixture is not uniform throughout.
Explanation:
- Pure substances have a fixed composition and cannot be separated into simpler components by physical processes. They include elements (e.g., oxygen) and compounds (e.g., baking soda).
- Homogeneous mixtures are those in which the components are evenly distributed, and the composition is uniform throughout, like tap water. In such mixtures, you cannot easily identify or separate the individual components by simple physical means.
- Heterogeneous mixtures are those where the components are not uniformly distributed, and you can often see or separate the different substances. Sawdust and cola with ice are examples of heterogeneous mixtures.
Each type of substance plays a crucial role in different chemical processes, and understanding whether a substance is pure or a mixture helps in identifying how to separate, analyze, or manipulate it in laboratory settings.
