Category: Ch 1 – Chemical Reactions and Equations

Exothermic reaction – heat is evolved during a reaction. Most of the combination reactions are exothermic. Al + Fe2O3 → Al2O3 + Fe + heatCH4 + 2O2 → CO2 + 2H2O + heat Effect of oxidation reaction in everyday life Endothermic – Heat is required to carry out the reaction. 6CO2 + 6H2O + Sunlight → C6H12O6 + 6O2 GlucoseMost of the decomposition reactions are…

A redox reaction occurs when the oxidation states of the substrate change. The loss of electrons or an increase in the oxidation state of a chemical or its atoms is referred to as oxidation. The gain of electrons or a decrease in the oxidation state of a chemical or its atoms is referred to as…

More reactive element displaces a less reactive element from its compound or solution. Double displacement reaction or Precipitation reaction An exchange of ions between the reactants takes place to give new products.For example,  An insoluble compound called precipitate forms when two solutions containing soluble salts are combined. One of the best examples of precipitation reactions is…

A single reactant decomposes on the application of heat or light or electricity to give two or more products.Types of decomposition reactions:a. Decomposition reactions which require heat – thermolytic decomposition or thermolysis.                                              …

In a combination reaction, two elements or one element and one compound or two compounds combine to give one single product. When quicklime or calcium oxide (CaO) reacts with water, slaked lime [Ca(OH)2] is formed. During this reaction, a large amount of heat is released. So, this reaction is an exothermic Reaction. CaO + H2O →…

Types of chemical reactions Taking into consideration different factors, chemical reactions are grouped into multiple categories.Few examples are:● Combination● Decomposition● Single Displacement● Double displacement● Redox● Endothermic● Exothermic● Precipitation● Neutralisation

Example: aCaCO3 + bH3PO4 → cCa3(PO4)2 + dH2CO3 Set up a series of simultaneous equations, one for each element. Ca: a=3c C: a=d O: 3a+4b=8c+3d H: 3b=2d P: b=2c Let’s set c=1 Then a=3 and d = a = 3 b = 2c = 2 So a=3; b=2; c=1; d=3 The balanced equation is 3CaCO3 + 2H3PO4 → Ca3 (PO4)2 + 3H2CO3

Law of Conservation of mass According to the law of conservation of mass, no atoms can be created or destroyed in a chemical reaction, so the number of atoms for each element in the reactants side has to balance the number of atoms that are present in the products side.In other words, the total mass…

Word equation A  word equation is a chemical reaction expressed in words rather than chemical formulas. It helps identify the reactants and products in a chemical reaction. A chemical reaction is described using a word equation, which is a shorthand manner of expressing it. The names of the reactants are shown on the left side of a word equation.…

A chemical reaction can be determined with the help of any of the following observations:a) Evolution of a gasb) Change in temperaturec) Formation of a precipitated) Change in coloure) Change of state