Answer:
By balancing the chemical equation
Explanation:
The Law of Conservation of Matter states that matter cannot be destroyed nor created.
That is, you must have the same amount of matter before and after a reaction.
Atoms are made of matter, so you must have the same number of each type of atom in the reactants as in the products. You must balance the equation.
Consider the reaction
2H₂ + O₂ ⟶ 2H₂O
You must have 2s in front of H₂ and H₂O to balance the atoms.
They give you four atoms of H and two atoms of O on each side of the arrow.
Answer:

Explanation:
We are given the formula:

This is a molecular formula, because it contains nonmetals.
1. Name the first element
The first element is phosphorous (P). Since this is the first element and there is only one, we don't need a prefix.
2. Second element
The second element is chlorine (Cl). It has a subscript of 5, so we must add the prefix of <u>hepta</u>-.
- Phosphorous heptachlorine
Add the ending of -ide.
- Phosphorous heptachloride
The prefix used for the second element is hepta. The compound name is phosphorous heptachloride.