Which of the following equations is correctly balanced for the reaction between solid lead(II) sulfide and oxygen gas to produce solid lead(II) oxide and sulfur dioxide gas?
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Correct answer
B. 2PbS + 3O2 → 2PbO + 2SO2
Principle or equation
A balanced chemical equation must have the same number of each type of atom on both sides.
Why this answer is correct
Start with PbS + O2 → PbO + SO2. Balance Pb and S: each side has 1 Pb and 1 S. Oxygen: left has 2, right has 1+2=3. To balance, multiply PbS, PbO, SO2 by 2: 2PbS + O2 → 2PbO + 2SO2. Now O: left has 2, right has 2+4=6. To get 6 O on left, use 3O2. Balanced: 2PbS + 3O2 → 2PbO + 2SO2.
Example
For 2PbS + 3O2 → 2PbO + 2SO2, atoms: Pb=2, S=2, O=6 on both sides.
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