BALANCING SIMPLE CHEMICAL EQUATION | J S S 3 BASIC SCIENCE | CHEMISTRY
BALANCING SIMPLE CHEMICAL EQUATION | J S S 3 BASIC SCIENCE | CHEMISTRY
Balancing Simple Chemical Equations
Matter is anything that has mass and occupies space. It is the substance that makes up the physical universe, and it can exist in various forms, such as solids, liquids, gases, and plasma. Everything around us, from air to water to the objects we interact with, is made of matter.
The Law of conservation of mass says that “Atoms are neither created, nor destroyed, during any chemical reaction.” Thus, the same collection of atoms is present after a reaction as before the reaction. The changes that occur during a reaction just involve the rearrangement of atoms.
A chemical reaction
A chemical reaction is a process in which substances (reactants) undergo a transformation to form new substances (products). During a chemical reaction, the chemical bonds between atoms are broken and reformed, leading to a change in the chemical composition of the substances involved. BALANCING SIMPLE CHEMICAL EQUATION | J S S 3 BASIC SCIENCE | CHEMISTRY
Key Features of Chemical Reactions:
- Reactants: The starting substances that participate in the reaction.
- Products: The new substances formed as a result of the reaction.
- Energy Changes: Chemical reactions often involve the release or absorption of energy, usually in the form of heat, light, or electricity.
- Exothermic reactions: Release energy (e.g., combustion).
- Endothermic reactions: Absorb energy (e.g., photosynthesis).
- Conservation of Mass: In a chemical reaction, the total mass of the reactants is equal to the total mass of the products, following the law of conservation of mass.
Chemical reactions are represented on paper by chemical equations.
For example, hydrogen gas (H2) can react (burn) with oxygen gas (O2) to form water (H2O). The chemical equation for this reaction is written as:
The simplest and most generally useful method for balancing chemical equations is “inspection,” better known as trial and error. The following is an efficient approach to balancing a chemical equation using this method.
- Identify the most complex substance.
- Beginning with that substance, choose an element that appears in only one reactant and one product, if possible. Adjust the coefficients to obtain the same number of atoms of this element on both sides.
- Balance polyatomic ions (if present) as a unit.
- Balance the remaining atoms, usually ending with the least complex substance and using fractional coefficients if necessary. If a fractional coefficient has been used, multiply both sides of the equation by the denominator to obtain whole numbers for the coefficients.
- Check your work by counting the numbers of atoms of each kind on both sides of the equation to be sure that the chemical equation is balanced.
Balancing chemical equations ensures that the number of atoms of each element on the reactants side equals the number on the products side, following the law of conservation of mass. This law states that matter cannot be created or destroyed in a chemical reaction.
Steps in Balancing a Chemical Equation:
- Write the Unbalanced Equation: Write the chemical formulas of the reactants and products.
- Count the Atoms of Each Element: Determine the number of atoms of each element in both the reactants and products.
- Balance One Element at a Time: Use coefficients (numbers placed before the chemical formulas) to balance the atoms. Never change subscripts in the chemical formulas.
- Check All Elements: Ensure all elements are balanced.
- Double-check the Equation: Confirm that the number of atoms of each element is the same on both sides of the equation.
To demonstrate this approach, let’s use the combustion of n-heptane (Equation 3.1.3) as an example.
Identify the most complex substance. The most complex substance is the one with the largest number of different atoms, which is C7H16
We will assume initially that the final balanced chemical equation contains 1 molecule or formula unit of this substance.
Adjust the coefficients. Try to adjust the coefficients of the molecules on the other side of the equation to obtain the same numbers of atoms on both sides. Because one molecule of n-heptane contains 7 carbon atoms, we need 7 CO2 molecules, each of which contains 1 carbon atom, on the right side:
C7H16+O2→7CO2+H2O (3.1.4)
Balance polyatomic ions as a unit. There are no polyatomic ions to be considered in this reaction.
Balance the remaining atoms. Because one molecule of n-heptane contains 16 hydrogen atoms, we need 8 H2O molecules, each of which contains 2 hydrogen atoms, on the right side:
C7H16+O2→7CO2+8H2O (3.1.5)
The carbon and hydrogen atoms are now balanced, but we have 22 oxygen atoms on the right side and only 2 oxygen atoms on the left. We can balance the oxygen atoms by adjusting the coefficient in front of the least complex substance, O2, on the reactant side:
C7H16(l)+11O2(g)→7CO2(g)+8H2O(g) (3.1.6)
Check your work. The equation is now balanced, and there are no fractional coefficients: there are 7 carbon atoms, 16 hydrogen atoms, and 22 oxygen atoms on each side. Always check to be sure that a chemical equation is balanced.
The assumption that the final balanced chemical equation contains only one molecule or formula unit of the most complex substance is not always valid, but it is a good place to start.
SIMPLE CHEMICAL EQUATION | J S S 3 BASIC SCIENCE | FIRST TERM
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