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chemical reaction and chemical equation (Factors Affecting The Rates of…
chemical reaction and chemical equation
Introduction
A chemical reaction is all about chemical change. The ripening of fruits, photosynthesis, tarnishing of iron, burning of woods, digestion of foods, and even cooking foods are few examples of chemical changes and chemical reactions happening around us and even inside our bodies.
A chemical reaction involves the transformation of one or more substances into another substance or substances. it involves a change in composition and is represented by a chemical equation.
A chemical equation provides a concise picture of a chemical change. It is used to convey the pertinent information about the chemical reaction which includes the substances involved and their quantitative ratio.
Chemical equations are representations of chemical reactions in terms of symbols of elements and formulas of compounds involved in the reactions.
The substances that enter into a chemical reaction are called reactants and the substances formed are the products.
Writing and Balancing Chemical Equations.
Steps in Writing a Balance Equation.
Write the symbols and formulas of the reactant/s on the left side of the arrow and symbol/s and formula/s of the products on the right. Monoatomic elements are represented by their symbols without subscript. Examples: Ca, Mg and Zn. Diatomic elements are represented by their symbols with subscript 2. Examples: H2, O2, N2, F2, CI2, Br2 and I2
2.Chemical changes occur in accordance with the Law of Conservation of Mass. It is therefore necessary to balance the number of atoms of each element in the reactants with the number of atoms of the same element in the product. Balancing chemical equations by inspection simply requires placing the coefficient before any of the symbol/s and formula/s until there are exactly the same numbers of each kind of atom on both sides of the equation.
Pointers to consider in using coefficient:
1.There is no need to write a coefficient, which is 1.
2.Use simplest whole numbers as coefficients
Example
Write the balance chemical equation for the reaction of hydrogen with oxygen to produce water.
2 H2 + O2 2H2O
Types of Chemical Reactions
Decomposition reaction is a type of reaction in which one compound decomposes to form two or more new substances. Usually heat is to cause these reactions to take place.
Combination reaction is a type of reaction in which two or more substances (either elements or compounds) react to form one product.
Example: 2 Na + Cl2 → 2NaCl
Decomposition reaction is a type of reaction in which one compound decomposes to form two or more new substances. Usually heat is to cause these reactions to take place.
Example: BaCl2 2H2O → BaCl2 + 2H2O
Factors Affecting The Rates of Chemical Reactions.
For a chemical reaction to take place, the molecules/ions of the reacting substances must collide. However, not all collisions may result to chemical change. For a collision to be effective, the colliding particles must be in the right orientation and must possess the necessary energy to reach the activation energy.
Activation energy is the added energy that reacting substances must have in order to take part in a chemical reaction. Any factor that affects the frequency and effectiveness of collisions of reacting substances also affects the rate of chemical reaction, which is the rate of formation of products or the rate of disappearance of reactants. These rates maybe affected by the following factors:
Activation energy is the added energy that reacting substances must have in order to take part in a chemical reaction. Any factor that affects the frequency and effectiveness of collisions of reacting substances also affects the rate of chemical reaction, which is the rate of formation of products or the rate of disappearance of reactants. These rates maybe affected by the following factors:
Concentration of Reactants
Concentration of a substance Is a measure of the number of molecules in a given volume. The rate of reaction of reaction increases as the molecules become more concentrated and become more crowded, hence, there is an increase in the frequency of collisions. Concentration can be expressed as moles per liter for reactions carried out in liquid solutions. For reactions involving gases, the concentration is expressed in terms of the pressure of the individual gases.
Temperature
An increase in temperature will cause the molecules to move rapidly resulting in more collisions. Because they are moving rapidly, they have sufficient energy and they collide with greater impact.
Catalyst
A catalyst is a substance that alters the speed of reaction without itself undergoing a permanent chemical change. Catalyst are usually used to increase the speed of chemical reaction, but there are also catalysts called inhibitors or negative catalysts, which slow down a chemical reaction.
Example:
2SO2 + O2 → 2SO2 (SLOW)
2NO + O2 → 2NO2 (FASTER)
The catalyst forms an intermediate compound with one of the reactants.
NO2 + SO2 → SO3 + NO
The catalyst is regenerated
Catalysts are important in industrial processes because aside from increasing the production, their use cut off production cost. Enzymes, which are the biological catalysts, metabolize reactions in our body.
Example:
Invertase cleaves sucrose (table sugar) into simple sugars, glucose and fructose, glucose in the form absorbed in the bloodstream