Identify each of the following changes of state as melting, freezing, sublimation, or deposition: a. Dry ice in an ice-cream cart disappears.

Verified step by step guidance

1. Identify the initial state of the substance: Dry ice is solid carbon dioxide (CO2).
2. Determine the final state of the substance: The dry ice disappears, indicating it transitions directly to a gas.
3. Recognize the process: When a solid changes directly to a gas without passing through the liquid state, it is called sublimation.
4. Apply the concept to the scenario: Since dry ice transitions from solid to gas, this change of state is sublimation.
5. Conclude: The disappearance of dry ice in an ice-cream cart is an example of sublimation.

Key Concepts

Sublimation

Sublimation is the process where a solid transitions directly into a gas without passing through the liquid state. This occurs under specific conditions of temperature and pressure. In the context of dry ice, which is solid carbon dioxide, it sublimates at temperatures above -78.5°C, resulting in the gas disappearing into the air, which is what happens in the ice-cream cart.

Dry Ice

Dry ice is the solid form of carbon dioxide (CO2) and is commonly used as a refrigerant. Unlike regular ice, dry ice does not melt into a liquid but instead sublimates directly into carbon dioxide gas. This property makes it useful for keeping items cold without the mess of water, especially in food transportation and storage.

Phase Changes

Phase changes refer to the transitions between different states of matter: solid, liquid, and gas. These changes occur due to variations in temperature and pressure. Understanding phase changes is crucial for identifying processes like melting, freezing, sublimation, and deposition, as they describe how substances behave under different conditions.