Apply the concept of Law of Conservation of Mass in balancing chemical equations.
Directions: Balance the
following chemical equations
Show your solution.
Answer (1)
The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction. This means that the number of atoms of each element must be the same on both sides of a chemical equation. To balance chemical equations, we adjust the coefficients (the numbers in front of compounds) without changing the chemical formulas. Let's balance the given chemical equations : a) [tex]Fe + O_2 \rightarrow Fe_2O_3[/tex] Count the atoms: Left: Fe = 1, O = 2 Right: Fe = 2, O = 3 Balance Iron (Fe) first: [tex]2Fe + O_2 \rightarrow Fe_2O_3[/tex] Now count again: Left: Fe = 2, O = 2Right: Fe = 2, O = 3 To balance oxygen, put a coefficient of 3/2 (or 1.5) in front of [tex]O_2[/tex]: [tex]2Fe + \frac{3}{2}O_2 \rightarrow Fe_2O_3[/tex] To eliminate the fraction, multiply everything by 2: [tex]4Fe + 3O_2 \rightarrow 2Fe_2O_3[/tex] b) [tex]H_2 + Cl_2 \rightarrow HCl[/tex] Count the atoms: Left: H = 2, Cl = 2Right: H = 1, Cl = 1 Balance: [tex]H_2 + Cl_2 \rightarrow 2HCl[/tex] c) [tex]Ag + H_2S \rightarrow Ag_2S + H_2[/tex] Count the atoms: Left: Ag = 1, H = 2, S = 1Right: Ag = 2, H = 2, S = 1 Balance silver (Ag): [tex]2Ag + H_2S \rightarrow Ag_2S + H_2[/tex] d) [tex]CH_4 + O_2 \rightarrow CO_2 + H_2O[/tex] Count the atoms: Left: C = 1, H = 4, O = 2Right: C = 1, H = 2, O = 3 Balance hydrogen by putting a coefficient of 2 in front of [tex]H_2O[/tex]: [tex]CH_4 + O_2 \rightarrow CO_2 + 2H_2O[/tex] Now, count: Left: C = 1, H = 4, O = 2Right: C = 1, H = 4, O = 4 Balance oxygen: [tex]CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O[/tex] e) [tex]HgO \rightarrow Hg + O_2[/tex] Count the atoms: Left: Hg = 1, O = 1Right: Hg = 1, O = 2 Balance oxygen: [tex]2HgO \rightarrow 2Hg + O_2[/tex] f) [tex]Co + H_2O \rightarrow Co_2O_3 + H_2[/tex] Count the atoms: Left: Co = 1, H = 2, O = 1 Right: Co = 2, H = 2, O = 3 Balance cobalt (Co) and then oxygen: [tex]3Co + 3H_2O \rightarrow Co_2O_3 + 3H_2[/tex] Now all equations are balanced while following the Law of Conservation of Mass!
