Answers:
The equation balanced is 2Sb + 3 Cl₂ → 2SbCl₃
Explanation:
To balance the equation that represents a chemical reaction you use coefficients in front of every different substance: compound, separate atoms or ions.
The coefficients are used to ensure compliance of mass conservation law in chemical reactions: the number of atoms of the same kind on the reactant side must equal the number of atoms of the same kind on the product side.
Balancing chemical equations is an algebraic procedure, you just must use multiplication and addition.
Coefficients are used to indicate the number of units of substances present and subscripts are used to indicate the number of each kind of atoms inside each unit. You can modify coefficients but not subscripts, since coefficients just change the number of units, but subscripts indicate the composition of the substance.
The coefficient 1 is understood in front of any substance if none coefficient is shown. The same is true for subscripts: subscript 1 is assumed if none coefficient is at the right corner of an atom.
This is how you balance the given reaction:
1) First step: balance Cl atoms
Atom Reactant side Product side:
Cl Cl₂ ⇒ 1×2 = 2 Cl₃ ⇒ 1×3 = 3
Conclusion: put a 3 in front of Cl₂ in fron of SbCl₃
Preliminar result: Sb + 3 Cl₂ → 2SbCl₃
Now there are 3×2 = 6 atoms of Cl in the reactant side and 2×3 atoms of Cl in the product side.
2) Second step: balance Sb atoms
Atom Reactant side Product side
Sb 1×1 = 1 2×1 = 2
Conclusion: put a 2 in front of Sb atom in the reactant side:
Second preliminar result: 2Sb + 3 Cl₂ → 2SbCl₃
3) Count the atoms:
Atom Reactant side Product side
Sb 2 2
Cl 6 6
Conclusion: the equation is balanced.
Final result: 2Sb + 3 Cl₂ → 2SbCl₃
