The freezing point of a substance is the temperature at which it changes from a liquid to a solid state at a given pressure. In other words, it is the temperature at which the solid and liquid phases of a substance are in equilibrium. For pure substances, the freezing point remains constant under a given pressure. However, for a solution, the freezing point is lower than that of the pure solvent due to the presence of solute particles.
Presence of impurities: When a solute is added to a solvent, the freezing point of the solution is lower than that of the pure solvent. This phenomenon is known as freezing point depression.
Type of substance: Different substances have different freezing points. For example, water freezes at 0°C (32°F), while ethanol freezes at -114°C (-173°F).
Automotive industry: Antifreeze, a solution used in vehicle cooling systems, lowers the freezing point of water, preventing it from solidifying in cold temperatures.
Chemical processes: Many industrial processes involve controlling the freezing points of substances to achieve specific physical and chemical properties.
Study Guide
Here are some key points to remember when studying the freezing point:
Define the freezing point of a substance and understand the concept of equilibrium between solid and liquid phases.
Understand the factors that can affect the freezing point, including pressure, presence of impurities, and the type of substance.
Be familiar with real-life applications of freezing point in various fields, such as food preservation, automotive industry, and chemical processes.
Understanding the freezing point is crucial in many scientific and industrial contexts, and it forms the basis for numerous practical applications.
The Living Environment: Students understand that cells are the basic unit of life, that all life as we know it has evolved through genetic transfer and natural selection to create a great diversity of organisms, and that these organisms create interdependent webs through which matter and energy flow. Students understand similarities and differences between humans and other organisms and the interconnections of these interdependent webs.
Cells: Students describe how living things are made up of one or more cells and the ways cells help organisms meet their basic needs.
Give examples of organisms that consist of a single cell and organisms that are made of a collection of cells.