Question

Which set of coefficients will balance this chemical equation? __PbS(s) + __O2(g) → 2PbO(s) + 2SO2(g)

Answer 1

A two in both of the blanks will balence the equation. It will look like so:

2PbS(s) + 2O2(g) --> 2PbO(s) +2SO2(g)

Answer 2

Answer:

The balanced equation is:

2 PbS(s) + 3 O₂(g) → 2 PbO(s) + 2 SO₂(g)

Explanation:

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.

The subscripts next to each atom indicates the number of atoms in the equation. These must be added to observe the amount of each element on each side of the reaction. If the same atom appears in more than one molecule, you must add its quantities.

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.  

So in this case you have:

__PbS(s) + __O₂(g) → 2 PbO(s) + 2 SO₂(g)

Left side:  1 lead (Pb), 1 sulfur (S) and 2 oxygen (O).

Right side:  2 lead (Pb), 2 sulfur (S) and 6 (2+2*2) oxygen (O)

• Balancing oxygen first, you get:

__PbS(s) + 3 O₂(g) → 2 PbO(s) + 2 SO₂(g)

Left side:  1 lead (Pb), 1 sulfur (S) and 6 (3*2) oxygen (O).

Right side:  2 lead (Pb), 2 sulfur (S) and 6 (2+2*2) oxygen (O)

• Balancing the sulfur:

2 PbS(s) + 3 O₂(g) → 2 PbO(s) + 2 SO₂(g)

Left side:  2 lead (Pb), 2 sulfur (S) and 6 oxygen (O).

Right side:  2 lead (Pb), 2 sulfur (S) and 6  oxygen (O)

You can see that you finally have the same amount of each element on each side of the chemical reaction. So the balanced equation is:

2 PbS(s) + 3 O₂(g) → 2 PbO(s) + 2 SO₂(g)