Question

36. Write a balanced chemical equation for each chemical reaction. (a) Solid copper reacts with solid sulfur to form solid copper(I) sulfide. (b) Sulfur dioxide gas reacts with oxygen gas to form sulfur trioxide gas. (c) Aqueous hydrochloric acid reacts with solid manganese(IV) oxide to form aqueous manganese(II) chloride, liquid water, and chlorine gas. (d) Liquid benzene (C6H6) reacts with gaseous oxygen to form carbon dioxide and liquid water.

Answer 1

Answer:

a) 2Cu(s) + S(s) → Cu₂S(s)

b) 2SO₂(g) + O₂(g) → 2SO₃(g)

c) 4HCl(aq) +  MnO₂(s) → MnCl₂(aq) + 2H₂O(l) + Cl₂(g)

d) C₆H₆(l) + 15/2 O₂(g) → 6CO₂(g) + 3H₂O(l)

Explanation:

First, we have to write the chemical formulas for reactants and products. Then, to identify which is the state of matter of each compound (liquid: l, solid: s, aqueous: aq, gas: g). Finally, we write the equation and balance the atoms.

a) Solid copper reacts with solid sulfur to form solid copper(I) sulfide.

Reactants: solid copper (Cu(s)) and solid sulfur (S(s)). Product: copper(I) sulfide (Cu₂S) because sulfur anion has two negative charges (S⁻²) and we need two copper ions with one positive charge (Cu⁺) to obtain the neutral compound.

The balanced requires a coefficient of 2 for Cu(s) to balance the 2 Cu atoms on the products side:

2Cu(s) + S(s) → Cu₂S(s)

(b) Sulfur dioxide gas reacts with oxygen gas to form sulfur trioxide gas.

Reactants: sulfur dioxide (SO₂) and oxygen gas (which is a diatomic molecule: O₂). Products: sulfur trioxide gas (SO₃(s)).

The balanced equation is:

2SO₂(g) + O₂(g) → 2SO₃(g)

We need a coefficient of 2 for SO₂ and SO₃ to balance O and S atoms.

(c) Aqueous hydrochloric acid reacts with solid manganese(IV) oxide to form aqueous manganese(II) chloride, liquid water, and chlorine gas.

Reactants: aqueous hydrochloric acid (HCl(aq)) and solid manganese (IV) oxide (MnO₂(s), because we need two oxygen anions O²⁻ to neutralize 4 positive charges in Mn IV). Products: aqueous manganese(II) chloride (MnCl₂, because we need two chloride ions Cl⁻ to neutralize two positive charges in Mn(II)), liquid water (H₂O), and chlorine gas (Cl₂, because it is a diatomic molecule).

The balanced chemical equation is:

4HCl(aq) +  MnO₂(s) → MnCl₂(aq) + 2H₂O(l) + Cl₂(g)

(d) Liquid benzene (C₆H₆) reacts with gaseous oxygen to form carbon dioxide and liquid water.

Reactants: benzene (C₆H₆) and gaseous oxygen (O₂). Products: carbon dioxide (CO₂, because C has valence IV) and liquid water (H₂O).

The balanced chemical equation is:

C₆H₆(l) + 15/2 O₂(g) → 6CO₂(g) + 3H₂O(l)

In this case, we need a coefficient of 15/2 for O₂ because on the product side there are 15 atoms of O (12 in CO₂ and 3 in H₂O).