Rusting: It is the reaction of iron with air (oxygen) and water to form rust (hydrated iron(III) oxide). Rusting is a redox process. Many a times, this rusting needs to be prevented, and for that some methods have been devised, for example, rusting can be prevented by...
Aluminium Extraction: The main ore of aluminium is bauxite (aluminium oxide). After it is mined, it is first purified by adding it in sodium hydroxide. The impurities do not dissolve and are filtered off. The dissolved aluminium oxide is then precipitated out as...
In this chapter, we study about air, its pollutants, oxygen, hydrogen, water and more environmental issues and facts. Air and Oxygen: We all know that oxygen is important for human and animal life. It is even important for plant life. The process by which...
Hydrogen: We all know by now that hydrogen is the first element of the periodic table. It is the simplest of all atoms. It just has one proton. It is the only atom that has no neutron. The hydrogen atom has only one electron. It combines with another hydrogen atom to...
The Reactivity Series: Metals not only have same physical properties, they also undergo many similar chemical reactions. However, one metal may react more or less vigorously with a substance than another metal. The metal that reacts more vigorously is said to be more...
Reactions: Metals with acids: Many metals react with dilute acids to produce a salt and hydrogen. For example, Mg (s) + HCl -> (aq) MgCl + H2 In the above reaction, the salt magnesium chloride is formed. In all reactions of metals with hydrochloric acid, a...
The Displacement Reactions of Metals: More reactive metals can displace less reactive metals from their salt solutions, oxides, etc. for example, solid iron displaces copper ions from a solution of copper (II) sulphate. Due to the action of iron, copper metal is...
Steel: It is produced by purifying the pig iron from the blast furnace by burning off impurities with oxygen gas. Controlled amounts of carbon are then added (0.5% carbon is mild steel, 1.5% carbon is high carbon steel). Mild steel is an example of steel that is low...
Acids: Acid is a substance which produces hydrogen ions, H+, when it is dissolved in water. All acids contain hydrogen ions, but not all compounds that contain hydrogen are acids, e.g. NH3. This is because NH3 does not produce hydrogen ions in water. It is the...
Bases: A base is any metal oxide or hydroxide. This means that a base contains either oxide ions O2- or hydroxide ions OH-. We can also define a base as a substance that reacts with an acid to give a salt and water only. base + acid -> salt + water For...
Uses of Acids: Sulphuric acid: In making detergents In making fertilizers In car batteries Hydrochloric acid: In leather processing For cleaning metals Ethanoic acid: (In vinegar) To preserve food In making adhesives such as...
Uses of Bases: Ammonia solution: In window cleaning solutions. In fertilizers. Calcium oxide: In neutralizing acidic soil Sodium hydroxide: In making soaps and detergents
Concentration and Strength: The term concentration tells us how much a substance is dissolved in 1 dm3 of the solution. This is changeable, of course. By adding more of the substance, we increase its concentration. By adding more of the solvent, we decrease the...
Types of Oxides: An oxide is a compound of oxygen and another element. Most oxides can be grouped into four types: acidic oxides, basic oxides, amphoteric oxides, and neutral oxides. Acidic Oxides: Non-metals may form acidic oxides. Most acidic oxides...
All salts are ionic compounds. A salt is formed when a metallic ion or an ammonium ion replaces one or more hydrogen ions of an acid. We will study about this substance in detail in this chapter. Solubility: All nitrates, and all ammonium, sodium and potassium...
Preparation: We will learn three methods to prepare salts. Before deciding which method to use, we must know the answer to these two questions. Is the salt to be prepared soluble in water? Are the starting materials soluble in water? Method 1: This method is...
Qualitative Analysis: The process of identification of cations and anions is called qualitative analysis or salt analysis. We identify which cations (positive ions) are present in a salt by using aqueous sodium hydroxide, and aqueous ammonia. For cation...
Ammonia and its Uses Nitrogen: Nitrogen is a gas. It is the main constituent of air (78%). It plays an important role in the formation of animal and plant protein. It is also used in the manufacture of ammonia gas, an important industrial gas, through the Haber...
Uses of Ammonia: The production of ammonia is done on large scale and large quantities are produced because it has many important uses. Manufacture of Fertilizers: The main use of ammonia is in the manufacture of fertilizers. Approximately 75% of all ammonia...
Sulphuric Acid Hello students. In this chapter, we learn about how Sulphuric acid is manufactured by a process called contact process. But before we begin, let’s learn a little about the oxides of sulphur: sulphur dioxide and sulphur trioxide. Both oxides of sulphur...
Energy Profile Diagrams: To show the activation energy of a reaction, energy profile diagrams are used. This diagram is a way of representing the energy changes that occur during a chemical reaction. The energy difference between the products and reactants...
The speed at which a chemical reaction proceeds can vary, and is called the rate of reaction. We will study about this in detail in this chapter. I). Measuring Speed of Reaction: The speed of reaction can be found by measuring these quantities at regular time...
II). Factors Affecting Speed of Reaction: There are various factors that affect the speed of a chemical reaction, the major ones being: The temperature at which the reaction is occurring The concentration of the substances used (reactants) The pressure on the...
III). Catalysts and Enzymes: A catalyst is a substance which increases the rate of a chemical reaction by lowering its activation energy, without itself being chemically changed at the end of the reaction. It works by providing an alternate, more direct route from...
I). Covalent Bonds: The bond formed between atoms that share electrons is called a covalent bond. After bonding, each electron attains the electronic configuration of a noble gas, or attains stability. This bond is formed between a non-metal and a non-metal. ...
II). Metallic Bonding: Metal atoms are held strongly to each other by metallic bonding. In the metal lattice, the atoms lose their valence electrons and become positively charged. The valence electrons no longer belong to any metal atom and are said to be...
Chap 9: The Mole (Part 1) Understanding the concept of mole is extremely important in chemistry, as it will be there in almost everything related to this subject. From paper point of view, it will be important in MCQs and theory paper, as well as practical or A.T.P...
Chap 9: The Mole (Part 2) In the previous lecture, we learnt what the mole was, and did some related numerical questions related to it. Let’s go through a quick revision of the major points. A mole is a quantity of substance in grams which contains the Avogadro...
Factors Affecting Electrolysis: In electrolysis, when more than one type of cation or anion is present in a solution, only one cation or one anion are preferentially discharged. This is known as selective discharge of ions. Position in the Reactivity Series...
Industrial Application of Electrolysis: Electrolysis has many varied industrial applications. The extraction of metals from their ores, in particular aluminium, and the purification of metals, especially copper, are important industrial uses. Another large scale use...
Chemical to Electrical Energy: A device which converts chemical energy into electrical energy is called a cell, or battery (a collection of cells). It consists of a pair of dissimilar metals in an electrolyte. The more reactive metal dissolves and turns into ions,...
Exothermic and Endothermic Changes: An exothermic reaction is one where energy (heat) is given out causing a temperature rise in the surroundings. The temperature of the reaction mixture rises. The container feels hot. Examples of exothermic reactions include:...
Making and Breaking Bonds: An exothermic change occurs when chemical bonds are made. An endothermic change occurs when chemical bonds are broken. The overall energy change of a reaction is the difference between the energy given out when bonds are made and...
Activation Energy: All reactions need energy in order to get started, weather it is an endothermic reaction or an exothermic one. The minimum energy that reacting particles must possess in order for a chemical reaction to occur is called the activation energy,...
Chap 7: Ionic Bonding Dear students, from here the tricky part of chemistry starts. So as not to confuse you, I have divided the chapter of ‘bonding’ into two parts: ionic bonding, and covalent and metallic bonding. This lecture deals only with ionic bonding. ...
Chap 6: The Periodic Table of Elements The Periodic Table is an arrangement of elements in order of their increasing proton (atomic) number. Groups: The vertical columns of elements in the Periodic Table are called groups. There are eight groups in the...
III). Changes in State: Solid to Liquid: Melting Liquid to Solid: Freezing Liquid to Gas: Evaporation or Boiling Gas to Liquid: Condensation Solid to Gas: Sublimation Gas to Solid: Solidification Melting and boiling points are important in...
IV). Diffusion: Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. As it involves a movement of particles, it is only possible in liquids and gases. Gases diffuse faster than liquids as they are generally...
Element: An element is a substance that cannot be split into two or more simpler substances by chemical means or by electricity. Elements can be classified into metals and non-metals. Metals Non-metals Shiny appearance (lustrous) Dull appearance...
Chap 5: Atomic Structure Dear students, this lecture is about the atom and its structure. Understanding this structure in chemistry is essential to further understand things such as chemical properties, bonding, etc. The atom consists of a ‘nucleus’, and...
A pure substance is one that contains only one type of substance, i.e. only one type of atom or molecule. A mixture contains two or more different substances physically combined together. They can be separated by different methods of purification. Dissolving,...
Testing the Purity of substances: A pure substance has a fixed and exact melting point. A pure substance has a fixed and exact boiling point. A pure substance shows only one spot on a chromatogram.
II). Kinetic Particle Theory: The kinetic particle theory states that all matter is made up of tiny particles, and that these particles are in constant, random motion. However, the movement of these particles varies according to the state of matter. The Solid...
II). Collection of Gases: Speed of Chemical Reactions: In a chemical reaction where a gas is given off, we can measure the speed of the reaction by recording the volume of gas given off in a certain time interval, which can be measured using a gas syringe, or by...
I). Measurements: The study of chemistry requires the measurement of various quantities, such as mass and volume. Mass: The mass of a substance is the amount of matter it contains. Its unit is the gram (g) for small amounts or the kilogram (kg) for larger amounts. It...