Answer: the sequence is 1, 3, 1, 2.
Explanation:
1) Given equation: CS₂(l) + O₂(g) → CO₂(g) + SO₂(g)
2) To balance:
i) initially C is balanced: 1 atom in the left side, and 1 atom in the right sides
ii) Add coefficient 2 in front of SO₂ to have 2 atoms in each side.
That leads to: CS₂(l) + O₂(g) → CO₂(g) + 2SO₂(g)
iii) Count the O atoms; there are 2 atoms in the left, and 6 atoms in the right side. So, add a coefficient 3 in front of O₂ (in the left) and you get:
CS₂(l) + 3O₂(g) → CO₂(g) + 2SO₂(g)
4) You can verigy that now the equation is balanced:
C: 1 in the left, and 1 in the right
S: 2 in the left, and 2 in the right
O: 6 in the left, and 6 in the right.
5) So, the sequence is 1, 3, 1, 2.
Remember, when the none coefficient is shown it is because it is 1.
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