Answer to Question #271094 in Chemistry for burnok

Question

Balance in acidic medium. Show step by step process.

Iron (solid) reacts with hydrochloric acid (liquid) to form aqueous iron(II) chloride and gaseous

hydrogen.

Answer 1

Solution:

Unbalanced chemical equation (acidic medium):

Fe(s) + HCl(aq) → FeCl₂(aq) + H₂(g)

Step 1: Separate the half-reactions:

Fe(s) → Fe²⁺(aq)

H⁺(aq) → H₂(g)

Step 2: Balance elements:

Fe(s) → Fe²⁺(aq)

2H⁺(aq) → H₂(g)

Step 3: Balance the charge of each equation with electrons.

The iron reaction has no charge on the left side and (2+) on the right side. To balance, add 2 electrons to the right side:

Fe(s) → Fe²⁺(aq) + 2e⁻

For the other reaction, there is 2×(1+) = (2+) charge on the left and no charge on the right. So add 2 electrons to the left side:

2H⁺(aq) + 2e⁻ → H₂(g)

Step 4: Scale the reactions so that they have an equal amount of electrons.

In this case, it is already done.

Step 5: Add the reactions and cancel the electrons:

Fe(s) + 2H⁺(aq) → Fe²⁺(aq) + H₂(g)

Balanced chemical equation:

Fe(s) + 2HCl(aq) → FeCl₂(aq) + H₂(g)