Question

10
what is an acid
give three properties of an acid

12
give two differences between ion and molecules

Explanation:

Sub - question 1: What is an acid? Give three properties of an acid

• Definition of an acid: An acid is a substance that, in aqueous solution, produces hydrogen ions ($H^+$) (or hydronium ions $H_3O^+$). For example, hydrochloric acid ($HCl$) dissociates in water as $HCl

ightarrow H^++Cl^-$.

• Property 1 (Taste): Acids have a sour taste. For example, citric acid in lemons gives them a sour taste.
• Property 2 (Reaction with metals): Acids react with active metals (like $Zn$, $Mg$) to produce hydrogen gas. The reaction for zinc and sulfuric acid is $Zn + H_2SO_4

ightarrow ZnSO_4 + H_2\uparrow$.

• Property 3 (Reaction with bases): Acids react with bases in a neutralization reaction to form salt and water. For example, $HCl+NaOH

ightarrow NaCl + H_2O$.

• Difference 1 (Charge): Ions are charged particles (either positively charged - cations, or negatively charged - anions). For example, $Na^+$ (cation) and $Cl^-$ (anion). Molecules are neutral (they have no net charge). For example, $H_2O$, $O_2$ are neutral molecules.
• Difference 2 (Formation): Ions are formed by the gain or loss of electrons by atoms (or groups of atoms). For example, $Na$ atom loses an electron to form $Na^+$ ion. Molecules are formed by the sharing (in covalent bonds) or transfer (in ionic bonds, but the resulting compound is made of ions) of electrons between atoms. For example, $H_2$ molecule is formed by sharing of electrons between two $H$ atoms.

Answer:

• Definition: A substance that produces $H^+$ (or $H_3O^+$) ions in aqueous solution.
• Properties:
• Sour taste.
• Reacts with active metals to produce $H_2$ gas.
• Reacts with bases to form salt and water.

Sub - question 2: Give two differences between ion and molecules