Grade 9
  1. Matter and its nature  1.1. Introduction to matter  1.2. Physical and chemical properties of matter  1.3. States of matter  1.3.1. Solid state  1.3.2. Fluid state  1.3.3. Gaseous state  1.3.4. Plasma and Bose–Einstein condensate  1.4. Changes in the states of matter  1.4.1. Melting and freezing  1.4.2. Evaporation and Condensation  1.4.3. Sublimation and deposition  1.5. Classification of matter  1.6. Elements, Compounds, and Mixtures  1.7. Pure substances and impurities  1.8. Separation Techniques  1.8.1. Filtration  1.8.2. Distillation  1.8.3. Crystallization  1.8.4. Chromatography  1.8.5. Centrifugation  1.8.6. Sublimation  1.8.7. Decantation and sedimentation
  2. Atomic Structure  2.1. Discovery of atoms  2.2. Dalton's atomic theory  2.3. Structure of the atom  2.4. Subatomic particles  2.5. Atomic number and mass number  2.6. Isotopes and Isobars  2.7. Electronic configuration  2.8. Bohr's atomic model  2.9. Modern Atomic Model (Quantum Mechanical Model - Introduction)  2.10. Valency and chemical bonding
  3. C hemical reactions and equations  3.1. Introduction to Chemical Reactions  3.2. Chemical Equation Formulation  3.3. Balancing Chemical Equations  3.4. Types of Chemical Reactions  3.4.1. Combination Reactions  3.4.2. Decomposition reactions  3.4.3. Displacement reactions  3.4.4. Double displacement reactions  3.4.5. Redox reactions  3.4.6. Endothermic and Exothermic Reactions  3.5. Effects of chemical reactions  3.6. Energy Changes in Chemical Reactions  3.7. Catalysts and their role in reactions
  4. Periodic table and periodicity  4.1. History of Periodic Classification  4.2. Mendeleev's periodic table  4.3. Modern Periodic Table  4.4. Periods and groups in the periodic table and periodicity  4.5. Trends in the Periodic Table  4.5.1. Atomic size  4.5.2. Ionization Energy  4.5.3. Electron affinity  4.5.4. Electronegativity  4.5.5. Metallic and Non-Metallic Properties  4.6. Noble gases and their properties
  5. Chemical bond  5.1. Introduction to Chemical Bonding  5.2. Types of chemical bonds  5.2.1. Ionic bond  5.2.2. Covalent bond  5.2.3. Metallic bond  5.2.4. Hydrogen bonding  5.2.5. Van der Waals force  5.3. Properties of Ionic and Covalent Compounds  5.4. Molecular Structure and Geometry (VSEPR Theory - Basics)
  6. Acids, Bases and Salts  6.1. Introduction to Acids and Bases  6.2. Properties of Acids  6.3. Properties of bases  6.4. pH scale and its importance  6.5. Indicators and their uses  6.6. Neutralization reactions  6.7. Strength of Acids and Bases (Strong vs. Weak)  6.8. Preparation of salts  6.9. Uses of acids, bases and salts in daily life
  7. Metals and Nonmetals  7.1. Physical Properties of Metals  7.2. Physical Properties of Nonmetals  7.3. Chemical properties of metals  7.4. Chemical Properties of Nonmetals  7.5. Reactivity Series of Metals  7.6. Extraction of metals  7.7. Corrosion and its prevention  7.8. uses of metals and nonmetals
  8. Carbon and its compounds  8.1. Introduction to Carbon  8.2. Allotropes of carbon (diamond, graphite, fullerene)  8.3. Hydrocarbons  8.3.1. Hydrocarbons  8.3.2. Alkene  8.3.3. Alkynes  8.4. Functional groups in organic chemistry  8.5. Isomerism in organic compounds  8.6. Alcohols and Carboxylic Acids  8.7. Soaps and detergents  8.8. Polymers (Introduction to Natural and Synthetic Polymers)
  9. Solutions and Mixtures  9.1. Types of mixtures  9.2. Homogeneous and Heterogeneous Mixtures  9.3. Concentration of solutions  9.4. Solubility and factors affecting solubility  9.5. Suspensions and Colloids  9.6. Saturated, unsaturated and supersaturated solutions
  10. Air and atmosphere  10.1. Composition of air  10.2. Role of gases in the atmosphere  10.4. Acid rain and its effects  10.5. Greenhouse effect and global warming  10.6. Ozone layer and its depletion  10.7. Air pollution control measures
  11. Water and its importance  11.1. Composition and properties of water  11.2. Hardness of water (temporary and permanent hardness)  11.3. Causes of water pollution  11.4. Effects of Water Pollution  11.5. Water purification methods (filtration, boiling, chlorination)
  12. Industrial Chemistry  12.1. Introduction to Industrial Chemistry  12.2. Important industrial chemicals (sulfuric acid, ammonia, sodium hydroxide)  12.3. Chemical processes in industry  12.4. Uses of Industrial Chemistry in Daily Life  12.5. Environmental impact of industrial chemical processes

Grade 9 → Matter and its nature ↓


Pure substances and impurities


In the world around us, everything is made up of matter, which can exist in different forms. It is very important to understand the difference between pure substances and impurities in the field of chemistry. Let us understand these concepts in detail.

What is the matter?

Matter is everything that has mass and occupies space. It is composed of atoms and molecules and makes up the components of the universe. In its most basic classification, matter can be divided into pure substances and mixtures. Pure substances are further divided into elements and compounds, while mixtures are made up of two or more substances that are physically combined.

Pure substance

A pure substance contains only one type of particle. This means that it has a uniform and definite composition. Pure substances can be either elements or compounds.

Elements

Elements are the simplest forms of pure matter and cannot be broken down into simpler substances by chemical means. Each element is made up of one type of atom. Some common examples of elements include:

Oxygen (O), Hydrogen (H), Carbon (C), Nitrogen (N), Iron (Fe)
Blue box: represents a single element

Each element has its own unique properties. For example, oxygen is a gas at room temperature, while iron is a solid metal.

Compounds

Compounds are substances that form when two or more elements chemically combine in a certain ratio. Unlike mixtures, the components in a compound cannot be physically separated. Chemical reactions are needed to separate them. Some common examples include:

Water (H2O), Carbon Dioxide (CO2), Sodium Chloride (NaCl)
Red circle: indicates the compound

For example, water is a compound made up of two hydrogen atoms and one oxygen atom. The properties of compounds differ from the properties of their constituent elements.

Impurities

Impurities are non-native chemicals or substances present in a mixture that affect the properties of the substance. They may be components of the substance or introduced from the environment. Impurities can affect physical properties such as boiling point, melting point, and color as well as chemical activity.

Types of impurities

Impurities may be classified into two main types:

1. Deliberate inaccuracies

These are impurities that are intentionally added to a substance to improve its properties. For example, adding certain metals to iron to make stainless steel.

2. Unintentional errors

These are unwanted impurities that are introduced during manufacturing or handling processes. These may arise from raw materials, processing chemicals or pollutants.

Effects of impurities

Impurities can have both positive and negative effects on the properties of a substance:

  • Change in melting point: Impurities usually lower the melting point of a substance. For example, adding salt to ice lowers the melting point of ice.
  • Change in boiling point: Impurities can increase the boiling point.
  • Changes in physical properties: Impurities can change the color, hardness, and electrical conductivity of substances.
Grey box: indicates impurity

Separation of mixtures

Since compounds have a definite structure, separating a mixture into its components can be a challenging task. There are various physical methods to separate mixtures, such as:

1. Filtration

Used to separate solids from liquids in suspension. For example, sand can be separated from water by filtration using filter paper.

2. Distillation

A process used to separate components based on their boiling points. It is often used to purify liquids. For example, distillation of seawater can produce pure water by collecting the steam and condensing it.

3. Chromatography

A method used to separate and analyze the components of a mixture. It is particularly useful for separating colored substances, such as inks or dyes.

4. Evaporation

It is used to remove a liquid from a solution so that the solid matter is removed. An example of this is obtaining salt from brine, in which the water is allowed to evaporate.

Red line: represents the separation process

Real-life examples

Pure substances and impurities affect many aspects of daily life. Here are some common examples:

1. Food

Cooking often involves mixing pure ingredients, such as sugar and salt, with other substances. Impurities can affect the taste and safety of food products.

2. Medicines

Pharmaceuticals require a high level of purity to ensure safety and effectiveness. Impurities can affect the action of the drug or cause harmful side effects.

3. Environmental monitoring

Air and water are tested for impurities to determine the level of pollution. Pollutants such as heavy metals or chemical waste can have harmful effects on ecosystems and human health.

Conclusion

In conclusion, understanding the difference between pure substances and impurities is fundamental in the study of chemistry. Pure substances have a uniform composition, while impurities affect the physical and chemical properties of substances. Separation methods play an important role in obtaining pure samples for study and use. It is important to recognize the effects of impurities in a variety of fields, including science, industry, and health.

The diversity of matter, from the simplest elements to complex mixtures, defines the richness of the world. By exploring how pure substances and impurities interact, we can better understand the substances that shape our environment.


Grade 9 → 1.7


U
username
0%
completed in Grade 9

← Prev (1.6)
Elements, Compounds, and Mixtures
Next (1.8) →
Separation Techniques

Comments 



Pure substances and impurities

https://www.chemistryelite.com/g9/1.7?ceal=en