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melting point

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Secondary Information

Definition

The melting point of a substance is the temperature at which it changes from a solid to a liquid. This happens when the molecules in the solid gain enough energy to overcome the forces of attraction between them. The melting point of a substance is a physical property that is unique to that substance.

The melting point of a substance depends on the strength of the forces of attraction between its molecules. Substances with strong forces of attraction, such as metals, have high melting points. Substances with weak forces of attraction, such as ice, have low melting points.

The melting point of a substance can also be affected by pressure. When pressure is applied to a solid, the molecules are forced closer together, which increases the forces of attraction between them. This can raise the melting point of the substance.

The melting point of a substance is an important property in many different fields, including geology, chemistry, and biology. For example, melting point is used to identify minerals, to determine the purity of chemicals, and study the properties of biological cells.

How can the word be used?

The melting point of gold is 1,064 degrees Celsius.

melting point

Different forms of the word

Noun:

  • melting point.
  • liquefaction point.
  • fusion point.

Adjective:

  • melting-point.

Verb:

  • melt.
  • liquefy.
  • fuse.

Etymology

The word "melting point" comes from the Old English word "meltan," which means "to become liquid through heat." The word "meltan" is also the source of the modern English words "melt" and "molten.".

The word "melting point" first appeared in English in the 17th century. It is a compound word, made up of the words "melt" and "point." The word "point" in this context means "a specific temperature.".

So, the word "melting point" literally means "the temperature at which a substance melts.".

Question

What is the melting point of something?

AQA Science Exam Question and Answer

Question:

Define the concept of a melting point and explain its significance in identifying substances. Provide examples of how melting points are used in practical applications, such as quality control and material characterisation.

Answer:

The melting point of a substance is the temperature at which it transitions from a solid to a liquid state. It is a unique physical property that helps identify and characterise different materials. Each substance has a specific melting point under standard atmospheric pressure, which remains relatively constant as long as the pressure remains constant.

For instance, the melting point of pure water is 0 degrees Celsius (32 degrees Fahrenheit) under normal pressure. This value remains consistent across various samples of pure water.

Melting points are crucial in various practical applications. In quality control, they serve as a benchmark to ensure the purity and authenticity of substances. For instance, pharmaceutical companies use melting point analysis to verify the identity and quality of drugs. If a sample's melting point deviates significantly from the expected value, it might indicate impurities or a different compound.

Material characterisation also relies on melting points. Different materials have distinct melting points due to variations in their molecular structures. By analysing the melting points of various materials, scientists can understand their composition, behaviour, and potential applications.