Difference Between a Coefficient and a Subscript | Sciencing
The balanced equation for the combustion of methane shows that one molecule of Chemical formulas can have both coefficients and subscripts. In these. Yes, there is a difference, and it does matter! The placement of subscripts and coefficients tells you how the substances are put together on the. There are subscripts, which are part of the chemical formulas of the reactants and products and there are coefficients.
Explain the role of the Law of Conservation of Mass in a chemical reaction. Even though chemical compounds are broken up and new compounds are formed during a chemical reaction, atoms in the reactants do not disappear nor do new atoms appear to form the products. In chemical reactions, atoms are never created or destroyed. The same atoms that were present in the reactants are present in the products - they are merely reorganized into different arrangements.
In a complete chemical equation, the two sides of the equation must be present on the reactant and the product sides of the equation. Coefficients and Subscripts There are two types of numbers that appear in chemical equations. There are subscripts, which are part of the chemical formulas of the reactants and products and there are coefficients that are placed in front of the formulas to indicate how many molecules of that substance is used or produced.
You cannot change subscripts in a chemical formula to balance a chemical equation; you can change only the coefficients. Changing subscripts changes the ratios of atoms in the molecule and the resulting chemical properties.Balancing Chemical Equations and Using Stoichiometric Coefficients
For example, water H2O and hydrogen peroxide H2O2 are chemically distinct substances. The subscripts are part of the formulas and once the formulas for the reactants and products are determined, the subscripts may not be changed. The coefficients indicate the number of each substance involved in the reaction and may be changed in order to balance the equation.
Generally, whole-number coefficients are used. In balancing equations, it is important to understand the difference between a coefficient in front of a formula and a subscript in a formula.
Refer to Figure 3. Notice that changing a subscript in a formula—from H2O to H2O2, for example—changes the identity of the chemical. The substance H2O2, hydrogen peroxide, is quite different from water. Subscripts should never be changed in balancing an equation.
Chemistry: The Central Science, Chapter 3, Section 1
In contrast, placing a coefficient in front of a formula changes only the amount and not the identity of the substance; 2H2O means two molecules of water, 3H2O means three molecules of water, and so forth.
Notice that the number of atoms of each type listed under composition is obtained by multiplying the coefficient and the subscript associated with each element in the formula.
- Your Answer
- Subscript Example
- Coefficient Example
To illustrate the process of balancing equations, consider the reaction that occurs when methane, CH4, the principal component of natural gas, burns in air to produce carbon dioxide gas, CO2, and water vapor, H2O. Both of these products contain oxygen atoms that come from O2 in the air. We say that combustion in air is "supported by oxygen," meaning that oxygen is a reactant. The unbalanced equation is [3. In our example both C and H appear in only one reactant and, separately, in one product each, so we begin by focusing attention on CH4.
Let's consider first carbon and then hydrogen. Therefore, the coefficients for these substances must be the same, and we choose them both to be 1 as we start the balancing process.
If we place a coefficient 2 in front of H2O, there will be four H atoms on each side of the equation: If we place a coefficient 2 in front of O2, we complete the balancing by making the number of O atoms equal on both sides of the equation: For most purposes a balanced equation should contain the smallest possible whole-number coefficients, as in this example.
7.4: How to Write Balanced Chemical Equations
The drawings of the molecules involved call attention to the conservation of atoms through the reaction. The approach we have taken to balancing Equation 3. We balance each kind of atom in succession, adjusting coefficients as necessary.
This approach works for most chemical equations. The physical state of each chemical in a chemical equation is often indicated parenthetically.