Скачать или смотреть How to Write the Formula for Iron (III) Sulfate – Step-by-Step Explanation

In this video, we’ll go step by step to write the chemical formula for iron(III) sulfate using the criss-cross method.

First, we identify the charges:

Iron(III) (Fe³⁺) has a +3 charge (from the Roman numeral in the name).
Sulfate (SO₄²⁻) is a polyatomic ion with a -2 charge.

Since the charges don’t cancel out directly, we use the criss-cross method to balance them:

The 2 from sulfate goes to iron → Fe₂
The 3 from iron goes to sulfate → (SO₄)₃
Because we have more than one sulfate ion, we use parentheses around SO₄. This gives us the final formula:

Fe₂(SO₄)₃ ✅

Finally, we check our work:

2 Fe³⁺ → +6 total charge
3 SO₄²⁻ → -6 total charge
Since +6 and -6 cancel, the compound is neutral!

That’s it! Now you know how to write the formula for iron(III) sulfate using the criss-cross method.