Balance the following chemical equation: Al + HCl —> AlCl3 + H2
The correct answer and explanation is:
Balanced Equation:
2Al + 6HCl → 2AlCl₃ + 3H₂
Explanation:
Balancing a chemical equation means ensuring that the number of atoms of each element on the reactant side is equal to the number of atoms on the product side. This maintains the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.
In the unbalanced equation:
Al + HCl → AlCl₃ + H₂
Start by examining each element:
- Aluminum (Al):
On the left side, there is 1 atom of aluminum. On the right side, AlCl₃ contains 1 atom of aluminum. So aluminum is already balanced. - Chlorine (Cl):
On the left side, HCl provides 1 chlorine atom per molecule. On the right side, AlCl₃ has 3 chlorine atoms. To balance chlorine, you need 3 HCl molecules to supply 3 Cl atoms.
This gives:
Al + 3HCl → AlCl₃ + H₂ - Hydrogen (H):
On the left, 3 HCl molecules provide 3 hydrogen atoms. On the right, H₂ is a diatomic molecule, meaning it contains 2 hydrogen atoms per molecule. Since 3 is not divisible evenly by 2, you will need to multiply everything to get even numbers.
To balance hydrogen properly, consider using 6 HCl molecules:
Al + 6HCl → 2AlCl₃ + 3H₂
Now count the atoms:
- Aluminum: 2 atoms on both sides.
- Chlorine: 6 Cl atoms from 6 HCl molecules match 2 AlCl₃ molecules (each has 3 Cl atoms).
- Hydrogen: 6 H atoms on the left yield 3 H₂ molecules on the right (3 × 2 = 6 H atoms).
Thus, the equation is balanced. The coefficients 2, 6, 2, and 3 ensure all atoms are equal on both sides and reflect the correct molar ratios needed in the reaction.