Chloride Compounds

Which of the following is an example of a chloride compound?

• CaCl₂

• KNO₃

• NH₃

• Na₂SO₄

Answer explanation

CaCl₂ is a chloride compound, consisting of calcium and chlorine. The other options, KNO₃ (nitrate), NH₃ (ammonia), and Na₂SO₄ (sulfate), do not contain chloride ions.

What happens at the atomic level when a chloride compound dissolves in water?

• The chloride compound remains a solid and does not dissociate.

• The compound reacts with water to form a precipitate.

• The ionic bonds break, releasing individual cations and Cl⁻ anions into the solution.

• The chloride ions combine to form a new solid compound.

Answer explanation

When a chloride compound dissolves in water, the ionic bonds break, allowing the individual cations and Cl⁻ anions to disperse into the solution, which is why this is the correct choice.

Which chloride compound is commonly known as table salt?

• CuCl₂

• KCl

• NaCl

• NH₄Cl

Answer explanation

The compound commonly known as table salt is sodium chloride, represented by the formula NaCl. Other options like CuCl₂, KCl, and NH₄Cl are different chloride compounds and not used as table salt.

Why does calcium chloride (CaCl₂) release heat when dissolved in water, while ammonium chloride (NH₄Cl) absorbs heat?

• A) CaCl₂ has a higher lattice energy than NH₄Cl.

• B) CaCl₂ has a higher hydration energy than its lattice energy, making dissolution exothermic.

• C) NH₄Cl decomposes into ammonia and hydrochloric acid, which absorbs heat.

• D) NH₄Cl undergoes an exothermic reaction with water.

Answer explanation

CaCl₂ releases heat when dissolved because its hydration energy exceeds its lattice energy, making the dissolution process exothermic. In contrast, NH₄Cl absorbs heat due to lower hydration energy compared to its lattice energy.

A scientist is trying to dissolve an unknown chloride compound in water. The solution becomes colder. What can be inferred about the compound?

• It has a higher hydration energy than lattice energy.

• Its dissolution is an exothermic process.

• Its dissolution is an endothermic process.

• The chloride compound is insoluble in water.

Answer explanation

The solution becoming colder indicates that heat is absorbed during dissolution, meaning the process is endothermic. Therefore, the correct inference is that its dissolution is an endothermic process.