To balance the equation C2H5OH + NaOH = C2H5ONa + H2O using the algebraic method step-by-step, you must have experience solving systems of linear equations. The most common methods are substitution/elimination and linear algebra, but any similar method will work.
Step 1: Label Each Compound With a Variable
Label each compound (reactant or product) in the equation with a variable to represent the unknown coefficients.
a C2H5OH + b NaOH = c C2H5ONa + d H2O
Step 2: Create a System of Equations
Create an equation for each element (C, H, O, Na) where each term represents the number of atoms of the element in each reactant or product.
C: 2a + 0b = 2c + 0d H: 6a + 1b = 5c + 2d O: 1a + 1b = 1c + 1d Na: 0a + 1b = 1c + 0d
Step 3: Solve For All Variables
Use substitution, Gaussian elimination, or a calculator to solve for each variable.
- 2a - 2c = 0
- 6a + 1b - 5c - 2d = 0
- 1a + 1b - 1c - 1d = 0
- 1b - 1c = 0
Use your graphing calculator's rref() function (or an online rref calculator) to convert the following matrix into reduced row-echelon-form:
[ 2 0 -2 0 0] [ 6 1 -5 -2 0] [ 1 1 -1 -1 0] [ 0 1 -1 0 0]
The resulting matrix can be used to determine the coefficients. In the case of a single solution, the last column of the matrix will contain the coefficients.
Simplify the result to get the lowest, whole integer values.
- a = 1 (C2H5OH)
- b = 1 (NaOH)
- c = 1 (C2H5ONa)
- d = 1 (H2O)
Step 4: Substitute Coefficients and Verify Result
Count the number of atoms of each element on each side of the equation and verify that all elements and electrons (if there are charges/ions) are balanced.
C2H5OH + NaOH = C2H5ONa + H2O
| C | 2 | 2 | ✔️ |
|---|---|---|---|
| H | 7 | 7 | ✔️ |
| O | 2 | 2 | ✔️ |
| Na | 1 | 1 | ✔️ |
Since there is an equal number of each element in the reactants and products of C2H5OH + NaOH = C2H5ONa + H2O, the equation is balanced.
The law of conservation of mass states that matter cannot be created or destroyed, which means there must be the same number atoms at the end of a chemical reaction as at the beginning. To be balanced, every element in C2H5OH + NaOH = C2H5ONa + H2O must have the same number of atoms on each side of the equation. When using the inspection method (also known as the trial-and-error method), this principle is used to balance one element at a time until both sides are equal and the chemical equation is balanced.
Step 1: Count the number of each element on the left and right hand sides
| Reactants (Left Hand Side) | Products (Right Hand Side) | ||||||
|---|---|---|---|---|---|---|---|
| Reactants | Products | ||||||
| C2H5OH | NaOH | Total | C2H5ONa | H2O | Total | ||
| C | 2 | 2 | 2 | 2 | ✔️ | ||
| H | 6 | 1 | 7 | 5 | 2 | 7 | ✔️ |
| O | 1 | 1 | 2 | 1 | 1 | 2 | ✔️ |
| Na | 1 | 1 | 1 | 1 | ✔️ | ||
The number of atoms of each element on both sides of C2H5OH + NaOH = C2H5ONa + H2O is equal which means that the equation is already balanced and no additional work is needed.