pure
Definition
Pure refers to a substance that is made up of only one type of atom or molecule. This means that it does not contain any impurities, which are other substances that are mixed in with the main substance.
Pure substances have a consistent composition and properties throughout the sample. This is because all of the atoms or molecules in the sample are identical. For example, pure water is made up of only hydrogen and oxygen atoms, and all of these atoms are identical.
Pure substances are often used in scientific experiments because they are more reliable. For example, if you are doing an experiment to test the properties of water, you want to make sure that the water is pure so that the results of your experiment are accurate.
Pure substances can be created through a variety of methods, such as distillation, crystallisation, and sublimation. Distillation is the process of separating a mixture of liquids into its components by boiling the mixture and then collecting the vapours that form. Crystallisation is the process of forming crystals from a solution. Sublimation is the process of a solid turning directly into a gas without going through the liquid state.
How can the word be used?
He drank pure water from the spring.
Different forms of the word
Adjective: not mixed with any other substance; not adulterated.
Adjective: not having any immoral or corrupt qualities; innocent.
Adjective: (of colour) not mixed with white or black.
Adverb: in a pure manner; without any mixture.
Etymology
The word "pure" comes from the Latin word "purus", which means "unmixed".
The first recorded use of the word "pure" in English was in the 13th century.
Question
What does pure mean?
AQA Science Exam Question and Answer
Question:
Define the term "pure substance" in chemistry and provide an example of a common pure substance found in daily life.
Answer:
In chemistry, a "pure substance" refers to a substance that is composed of only one type of element or compound, with uniform and consistent properties throughout. It cannot be separated into simpler components using physical methods.
An example of a common pure substance found in daily life is distilled water. Distilled water is obtained by heating water to its boiling point, collecting the vapour, and then condensing it back into liquid form. During this process, impurities and dissolved minerals are left behind, resulting in water that consists of only H2O molecules. Distilled water has a consistent chemical composition and properties, making it a pure substance.
Unlike tap water, which may contain various minerals, salts, and impurities, distilled water is free from these additional substances. It is often used in laboratories and medical settings where the absence of contaminants is crucial. The fact that distilled water is a pure substance underscores its uniformity and the reliability of its properties, making it an important example to understand the concept of pure substances in chemistry.