Properties and Chemical Reactions of Acids and Bases

General Properties of Acids

• Acids are chemical substances characterized by having pH values of below 7.

• Physical properties:

  • Taste: When acids are present in edible substances, they are known to have a sour taste.

  • Damage: Acids are naturally corrosive, meaning they can cause damage to surfaces and living tissues upon contact.

• Ionic Behavior and Definition:

  • The defining characteristic of an acidic solution is the presence of hydrogen ions ($H^+$).

  • When acids are added to water ($H_2O$), they dissociate to form positively charged hydrogen ions ($H^+$).

  • Example dissociation using Hydrochloric acid ($HCl$):

  • $HCl_{(aq)} \rightarrow H^+_{(aq)} + Cl^-_{(aq)}$

• Chemical Neutralization: Acids are substances defined by their ability to neutralize a base, which results in the formation of a salt and water.

Reactions of Acids with Metals

• Reactivity Requirements: Not all metals react with dilute acids. Only metals located above hydrogen in the reactivity series will successfully react.

• General Reaction Formula:

  • $\text{acid} + \text{metal} \rightarrow \text{salt} + \text{hydrogen}$

• Product Characteristics:

  • The products consist of a salt and hydrogen gas ($H_2$).

  • Salt Naming: The specific name of the generated salt depends on the anion (negative ion) within the acid used and the specific metal involved.

• Specific Reactions of Magnesium ($Mg$) with Various Acids:

  • Hydrochloric Acid ($HCl$):

  • Salt Product: Magnesium chloride ($MgCl_2$).

  • Gas Product: Hydrogen ($H_2$).

  • Chemical Equation: $Mg + 2HCl \rightarrow MgCl_2 + H_2$

  • Sulfuric Acid ($H_2SO_4$):

  • Salt Product: Magnesium sulfate ($MgSO_4$).

  • Gas Product: Hydrogen ($H_2$).

  • Chemical Equation: $Mg + H_2SO_4 \rightarrow MgSO_4 + H_2$

  • Nitric Acid ($HNO_3$):

  • Salt Product: Magnesium nitrate ($Mg(NO_3)_2$).

  • Gas Product: Hydrogen ($H_2$).

  • Chemical Equation: $Mg + 2HNO_3 \rightarrow Mg(NO_3)_2 + H_2$

Reactions of Acids with Bases (Neutralization)

• Definition of Bases: Metal oxides and metal hydroxides serve as bases. Metal hydroxides that are soluble in water are specifically called alkalis.

• Neutralization Process: A neutralization reaction occurs when an acid and a base react together.

• General Reaction Formula for Neutralization:

  • $\text{acid} + \text{base} \rightarrow \text{salt} + \text{water}$

• Universal Products: In all acid-base neutralization reactions, the chemicals produced are consistently a salt and water ($H_2O$).