Definition properties types reactions and uses of acids bases and salts
FAQs on Acids Bases and Salts Complete Chemistry Guide
1. What are acids, bases, and salts in chemistry?
Acids are substances that produce H+ ions in water, bases produce OH- ions in water, and salts are ionic compounds formed from the neutralization of an acid and a base.
- According to the Arrhenius definition, acids increase H+ concentration in aqueous solution.
- Bases increase OH- concentration in aqueous solution.
- A salt is formed when H+ from an acid is replaced by a metal or NH4+ ion.
- Example: HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
2. What is the difference between strong and weak acids?
The key difference is that strong acids completely ionize in water, while weak acids only partially ionize.
- Strong acid example: HCl(aq) → H+(aq) + Cl-(aq)
- Weak acid example: CH3COOH(aq) ⇌ H+(aq) + CH3COO-(aq)
- Strong acids have very low pH (close to 0–3).
- Weak acids have higher pH compared to strong acids of the same concentration.
3. How do you define an acid according to Arrhenius, Brønsted–Lowry, and Lewis?
An acid is defined as an H+ donor by Arrhenius and Brønsted–Lowry, and as an electron pair acceptor by Lewis.
- Arrhenius acid: Produces H+ in water (e.g., HNO3).
- Brønsted–Lowry acid: Donates a proton (H+) to another species.
- Lewis acid: Accepts an electron pair (e.g., BF3).
4. What is a neutralization reaction?
A neutralization reaction is a chemical reaction between an acid and a base that forms salt and water.
- General form: Acid + Base → Salt + Water
- Example: H2SO4(aq) + 2NaOH(aq) → Na2SO4(aq) + 2H2O(l)
- Net ionic equation: H+(aq) + OH-(aq) → H2O(l)
5. What is the pH scale and how does it work?
The pH scale measures the acidity or basicity of a solution based on hydrogen ion concentration and ranges from 0 to 14.
- Formula: pH = −log[H+]
- pH < 7: acidic solution
- pH = 7: neutral solution (pure water)
- pH > 7: basic (alkaline) solution
6. How are salts formed from acids and bases?
Salts are formed when the hydrogen ion of an acid is replaced by a metal or ammonium ion during neutralization.
- Acid + Base → Salt + Water
- Example: HCl(aq) + KOH(aq) → KCl(aq) + H2O(l)
- The salt consists of the base’s cation (K+) and the acid’s anion (Cl-).
7. What is the difference between acids and bases?
The main difference is that acids donate H+ ions, while bases accept H+ ions or produce OH- ions in solution.
- Acids: Sour taste, turn blue litmus red, pH < 7.
- Bases: Bitter taste, turn red litmus blue, pH > 7.
- Acids react with metals to produce H2(g).
8. What are the types of salts in chemistry?
Salts are classified as neutral salts, acidic salts, and basic salts based on their effect on solution pH.
- Neutral salts: Formed from strong acid and strong base (e.g., NaCl).
- Acidic salts: Formed from strong acid and weak base (e.g., NH4Cl).
- Basic salts: Formed from strong base and weak acid (e.g., CH3COONa).
9. How do you calculate the pH of a strong acid solution?
To calculate the pH of a strong acid, first determine [H+] from its concentration and then apply the formula pH = −log[H+].
- Example: 0.01 M HCl fully dissociates, so [H+] = 0.01 M.
- pH = −log(0.01) = 2.
- For diprotic strong acids like H2SO4, account for both H+ ions if fully dissociated in basic problems.
10. Why do acids react with metals to produce hydrogen gas?
Acids react with reactive metals because H+ ions are reduced to hydrogen gas while the metal is oxidized.
- General reaction: Metal + Acid → Salt + H2(g)
- Example: Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
- The metal must be above hydrogen in the reactivity series.
