Mixtures
The components of a mixture can easily be separated by ordinary methods.mixture is a substance containing two or more elements or compounds in any proportion.
In a mixture, the components do not lose their identity. The common examples of
Mixtures are:
(i) Air is a mixture of several gases. The common gases present in air are oxygen, nitrogen, carbon dioxide, water vapour, etc.
(ii) Gun powder is a mixture of carbon, sulphur and nitre (potassium nitate).
(iii) Steel is a mixture of iron, carbon and small amount of magnesium, chromium, etc.
(iv) Syrup is a mixture of sugar and water.
Some other important mixtures are like, petroleum, lime water, alloys, smoke, etc
CHARACTERISTICS OF MIXTURE :
A mixture is a combination of two or more substances in which each substance retains its own chemical properties. Unlike compounds, mixtures are not formed through chemical bonding, and the components in a mixture can be separated by physical means. Here are some key characteristics of mixtures:
Physical Combination:
Mixtures are formed by physically combining substances, and no chemical reaction occurs during their formation.
The components of a mixture retain their individual properties.
Variable Composition:
The ratio of the components in a mixture can vary, and there is no fixed or specific ratio as seen in compounds.
Mixtures can have different concentrations of each component.
Separation:
Components of a mixture can be separated by physical methods such as filtration, distillation, chromatography, or evaporation.
This is in contrast to compounds, where separation typically involves breaking chemical bonds.
No New Substance Formed:
Mixing substances to form a mixture does not result in the creation of a new substance with unique properties.
The components of a mixture can be present in any proportion.
Physical State:
Mixtures can exist in different physical states such as solid, liquid, or gas, depending on the states of their individual components.
Properties:
The properties of a mixture are the sum of the properties of its individual components.
For example, a mixture of sand and salt will exhibit the characteristics of both sand and salt.
Homogeneity/Heterogeneity:
Mixtures can be homogeneous or heterogeneous.
A homogeneous mixture (solution) has uniform composition and appearance throughout (e.g., salt dissolved in water).
A heterogeneous mixture has uneven distribution and distinct phases (e.g., a mixture of oil and water).
Melting and Boiling Points:
Mixtures do not have specific melting or boiling points; instead, they have a range of temperatures over which they change state.
No Energy Changes During Mixing:
Unlike compounds, mixing substances to form a mixture does not involve energy changes such as the release or absorption of heat.
Examples:
Common examples of mixtures include air (a mixture of gases), a salad (a mixture of various vegetables), and seawater (a mixture of water and dissolved salts).
Types of Mixtures
Mixtures are of two types:
i) Homogeneous mixtures and
ii)Heterogeneous mixtures
i) Homogeneous mixtures:
A mixture in which constituents are mixed uniformly. For example, salt solution (sodium chloride dissolved in water), sugar solution (surgar dissolved in water), carbonated water (carbon dioxide dissolved in water), Alloys ( Brass is a mixture of copper and zinc etc.
Alloy is a homogenous mixture of two or more metals (Or) metal and non-metal.
ii) Heterogeneous mixtures :
Amixture in which constituents are not mixed uniformly. It has visible boundaries of separation between the various constituents. For example, undissolved sugar (solid phase) in sugar solution (liquid phase), smoke (mixture of air and carbon particles), mixture of iron and sulphur, mixture of sand and water, mixture of sodium chloride and iron filings etc.
If we see milk, it appears to be a homogeneous substance. However, if we observe milk with the help of a microscope, it appears as drops of fat suspended in a clear liquid. Thus, milk is also a heterogeneous mixture.