Question

1. Write a balanced equation describing each of the following chemical reactions. (Use the lowest possible whole number coefficients. Include states-of-matter under the given conditions in your answer.)

(a) When solid potassium chloride is added to aqueous sulfuric acid, hydrogen chloride gas and aqueous potassium sulfate are produced.

(b) Aqueous solutions of phosphoric acid and rubidium hydroxide react to produce aqueous rubidium dihydrogen phosphate and liquid water.

2. Four moles of hydrogen iodide (HI) gas react with one mole of oxygen (O₂) gas to produce two moles of iodine gas (I₂) and two moles of water gas (H₂O). Using this description of the reaction, write the corresponding chemical equation, showing the appropriate coefficients for each reactant and product. (Include states-of-matter under the given conditions in your answer.)

Answer 1

a)

2KCl(s) + H₂SO₄ (aq) ----> K₂SO₄ (aq) + 2HCl (g)

Both sides have the same number of an atom, so equation is balanced.

2 moles of solid potassium chloride react with 1mole of aqueous sulfuric acid to produce 1mole of aqueous potassium sulfate and 2 moles of hydrogen chloride gas.

KCl is a weak reducing agent, so it does not decompose into Cl₂. It only participates in replacement reactions.

b)

RbOH (aq) + H₃PO₄ (aq) ---> RbH₂PO₄ (aq) + H₂O(l)

Aqueous solutions of phosphoric acid and rubidium hydroxide react to produce aqueous rubidium dihydrogen phosphate and liquid water.

Rubidium hydroxide is a strong base. Its aqueous solution gives Rb⁺ and OH^-

RbOH (aq) ----> Rb⁺ + OH^-

H₃PO₄ acid is a triprotic acid, it gives out one proton and form dihydrogen phosphate anion

H₃PO_4(aq) ------> H₂PO₄^- + H⁺

The Rubidium cation will combine with the dihydrogen phosphate anion and gives aqueous rubidium dihydrogen phosphate. OH^- combined with H⁺ gives liquid water.

2)

4 HI(g)+ O₂ (g) ------> 2I₂ (g) + 2H₂O(g)

It is decomposition reaction. Four moles of hydrogen iodide decomposes and produces two moles of iodine gas and two moles of water. HI is a good reducing agent, so it decompose into I₂ very easily.