Chemical Equations 7th Topic 6

Presentation

Chemical Equations

Products

Arrow

Reactants

Coefficient

A chemical equation is a representation of a chemical reaction that displays the reactants and products with chemical formulas. The chemicals that enter a chemical reaction are called reactants. The chemicals that emerge from the response are known as the products. In a chemical equation, the reactants are on the left and the products are on the right. A + B C + D

Balancing Chemical Equations

Step by step

H₂ + O₂ → H₂O

Step 1: Write the Equation

Start by writing the chemical equation for the reaction you want to balance. A chemical equation shows the reactants on the left side and the products on the right side, separated by an arrow. For example, let's consider the reaction between hydrogen gas (H₂) and oxygen gas (O₂) to produce water (H₂O):

H₂ + O₂ → H₂O

Step 2: Count the number of atoms on each side

Count the number of atoms of each element on both sides of the equation. This includes the atoms in both the reactants and the products. Make a list of the atoms and their counts for each element. For example we have: H: 2 atoms on the left side, 2 atoms on the right side O: 2 atoms on the left side, 1 atom on the right side

H₂ + O₂ → H₂O

Step 3: Choose an element to start balancing

Select an element that appears in more than one molecule on either side of the equation. In our example, oxygen (O) is a good choice because it appears in two molecules on the left side and one molecule on the right side. This is the unbalanced equation.

H₂ + O₂ → 2H₂O

Step 4: Add Coefficients

To balance the number of oxygen atoms, add a coefficient ( a number in front of a molecule) to the molecule(s) that contain the element you choose. The coefficient multiplies the number of atoms in that molecule. For example, we can balance oxygen by adding a coefficient of 2 in front of the water molecule.

H₂ + O₂ → 2H₂O

Step 5: Check the balance

After adding the coefficient, check if the equation is balanced. Go back and count the atoms of the element you just balanced and verify that they are now equal on both sides. Now there are 4 hydrogen atoms on the right but only two on the left. This equation is still not balanced. What's next?

2H₂ + O₂ → 2H₂O

Step 6: Continue Balancing

Since the equation is not yet balanced, we place a coefficient of 2 in front of H₂ to get the final balanced equation of:

Na + H₂O → NaOH + H₂

N₂ + H₂ → NH₃

H₂O₂ → + H₂O + O₂

S + O₂ → SO₃

Na + I₂ → NaI

Practice: Try balancing the following equations then click on the box to the right of each to reveal the correct answer: