Question

In air, a silver object can tarnish due to the reaction of silver with hydrogen sulfide, a gas found in the air as a result of certain biological processes. ___Ag (s) + ___H2S (g) -----> ___ Ag2S (s) + ___ H2 (g) When this equation is balanced, what is the coefficient of Ag?

Answer 1

Answer:

The coefficient of Ag is 2.

Explanation:

___Ag (s) + ___H₂S (g) ⇒ ___ Ag₂S (s) + ___ H₂(g)

The Law of Conservation of Matter is also called the law of conservation of mass or the Law of Lomonósov-Lavoisier. This law postulates that "the mass is not created or destroyed, only transformed." This means that the reagents interact with each other and form new products with physical and chemical properties different from those of the reagents because the atoms of the substances are ordered differently. But the amount of matter or mass before and after a transformation (chemical reaction) is always the same, that is, the quantities of the masses involved in a given reaction must be constant at all times, not changing in their proportions when the reaction ends.

In others words, the law of conservation of matter states that since no atom can be created or destroyed in a chemical reaction, the number of atoms that are present in the reagents has to be equal to the number of atoms present in the products.

Then, you must balance the chemical equation. For that, you must first look at the subscripts next to each atom to find the number of atoms in the equation. If the same atom appears in more than one molecule, you must add its amounts :

Left side: 1 Ag, 2 H and 1 S

Right side: 2 Ag, 2 H and 1 S

The coefficients located in front of each molecule indicate the amount of each molecule for the reaction. This coefficient can be modified to balance the equation, just as you should never alter the subscripts.

By multiplying the coefficient mentioned by the subscript, you get the amount of each element present in the reaction.  

You can see that the elements H and S are balanced because we have the same quantity on both sides of the reaction. Then you must balance the Ag, so the reaction is:

2 Ag (s) + 1 H₂S (g) ⇒ 1 Ag₂S (s) + 1 H₂(g)

Now you have:

Left side: 2 Ag, 2 H and 1 S

Right side: 2 Ag, 2 H and 1 S

So, you have the same amount of each element to both of the reaction and this is balanced.

Then, the coefficient of Ag is 2.