Question

How would you balance this chemical equation: `2Sb + I_2 -> 2SbI_3`?

Answer 1

`2 Sb + 3 I_2 === 2 SbI_3`

Explanation:

There are six Iodines in the products so there must be six iodines in the reactants.

Iodine comes as diatomic gas molecule. ( as well as a grey crystal).

`3 xx I_2 = 6 I^-1` therefore it requires 3 `I_2` molecules to balance the equation

Answer 2

You follow a systematic procedure to balance the equation.

Explanation:

Start with the unbalanced equation:

`"2Sb" + "I"_2 → "2SbI"_3`

A method that often works is to balance everything other than `"O"` and `"H"` first, then balance `"O"`, and finally balance `"H"`.

Another useful procedure is to start with what looks like the most complicated formula.

The most complicated formula looks like `"SbI"_3`. It already has a 2 in front of it.

`"2Sb" + "I"_2 → color(red)(2)"SbI"_3`

Balance `"Sb"`:

There are `"2 Sb"` on the right, and there are `"2 Sb"` on the right. `"Sb"` is balanced.

`color(blue)(2)"Sb" + "I"_2 → color(red)(2)"SbI"_3`

Balance `"I"`:

We have fixed `"6 I"` on the right, so we need `"6 I"` on the left. Put a 3 in front of `"I"_2`.

`color(blue)(2)"Sb" + color(orange)(3)"I"_2 → color(red)(2)"SbI"_3`

Every formula now has a fixed coefficient. We should have a balanced equation.

Let’s check:

`bb("Atom"color(white)(m)"Left hand side"color(white)(m)"Right hand side")`
`color(white)(m)"Sb"color(white)(mmmmm)2color(white)(mmmmmmmm)2`
`color(white)(m)"I"color(white)(mmmmmm)6color(white)(mmmmmmmm)6`

All atoms balance. The balanced equation is

`2"Sb" + 3"I"_2 → 2"SbI"_3`