Arrhenius definitions: Acid → in water gives \(H^+\); Base → in water gives \(OH^-\). Examples: \(HCl\), \(H_2SO_4\); \(NaOH\), \(Ca(OH)_2\).

Dissociation (aq): \(\displaystyle NaCl(s)\xrightarrow{H_2O} Na^+(aq)+Cl^-(aq)\). Ions in water conduct electricity.

Strength vs Concentration: Strength = extent of ionization (strong/weak). Concentration = amount present (dilute/concentrated).

Basicity & Acidity: Basicity of acid = number of replaceable \(H^+\). Acidity of base = number of \(OH^-\) from one molecule.

pH scale (0–14): \(\text{pH}=7\) neutral, <7 acidic, >7 basic. Pure water at \(25^\circ C\): \([H^+]=10^{-7}\ \text{mol}\,\text{L}^{-1}\).

Neutralization: \(\displaystyle H^++OH^- \to H_2O\); overall: Acid + Base → Salt + Water.

Reactions: Acids + metals → salt + \(H_2\uparrow\); Metal oxides (basic) + acids → salt + water; Non-metal oxides (acidic) + bases → salt + water; (Bi)carbonates + acids → salt + \(CO_2\uparrow + H_2O\).

Salts by pH: Strong acid + strong base → neutral; strong acid + weak base → acidic; weak acid + strong base → basic.

Water of crystallization: e.g., \(CuSO_4\cdot5H_2O\), \(FeSO_4\cdot7H_2O\), \(Na_2CO_3\cdot10H_2O\), \(K_2SO_4\cdot Al_2(SO_4)_3\cdot24H_2O\).

Electrolysis of \(CuSO_4\) (aq): Cathode: \(\displaystyle Cu^{2+}+2e^- \to Cu(s)\). Anode (Cu): \(\displaystyle Cu(s)\to Cu^{2+}+2e^-\).

Electrolysis of water: volumes \(H_2:O_2=2:1\). Cathode: \(2H_2O+2e^- \to H_2+2OH^-\); Anode: \(2H_2O \to O_2+4H^++4e^-\).

1) Arrhenius acid?

Substance giving \(H^+\) in water (e.g., \(HCl\)).

2) Arrhenius base?

Substance giving \(OH^-\) in water (e.g., \(NaOH\)).

3) Alkali meaning?

Water-soluble base (e.g., \(KOH\), \(NH_3\) solution).

4) Basicity of \(H_2SO_4\)?

2 (dibasic).

5) Acidity of \(Al(OH)_3\)?

3 (tribasic base).

6) Unit of molarity?

\(\text{mol L}^{-1}\) (M).

7) Neutralization ionic equation?

\(\displaystyle H^+ + OH^- \to H_2O\).

8) pH of pure water at \(25^\circ C\)?

7 (neutral).

9) Gas with Mg + dil. HCl?

Hydrogen, burns with pop sound.

10) Nature of \(CO_2\) (oxide)?

Acidic oxide.

11) Example of amphoteric oxide.

\(\mathrm{Al_2O_3}\) or \(\mathrm{ZnO}\).

12) Colour change of blue vitriol on heating?

Blue \(\to\) white (\(CuSO_4\cdot5H_2O \to CuSO_4\)).

13) Universal indicator shows?

Colour varies with pH (0–14).

14) Conducting solutions contain?

Free ions (electrolytes).

15) pH of 1 M \(HCl\)?

\(\approx 0\) (very acidic).

16) pH of 1 M \(NaOH\)?

\(\approx 14\) (strongly basic).

17) Product with acid + carbonate?

Salt + \(CO_2\uparrow\) + \(H_2O\).

18) Salt from strong acid + strong base?

Neutral salt (pH ≈ 7).

19) Hydronium formula?

\(\mathrm{H_3O^+}\).

20) Ionic bond forms due to?

Electrostatic attraction between cation and anion.

1) Write dissociation of \(HCl\) in water.

\(\displaystyle HCl(aq)\to H^+(aq)+Cl^-(aq)\) (almost complete).

2) Write dissociation of \(NH_4OH\) in water.

Weak: \(\displaystyle NH_4OH \rightleftharpoons NH_4^+ + OH^-\).

3) Why does litmus turn red in acids?

Due to \(H^+\) presence; acid–base indicator behaviour.

4) Give equation: \(NaOH\) + \(HCl\).

\(\displaystyle NaOH+HCl\to NaCl+H_2O\).

5) Mg with dilute \(HCl\) (balanced).

\(\displaystyle Mg+2HCl\to MgCl_2+H_2\uparrow\).

6) Metal oxide + acid (example).

\(\displaystyle CuO+2HCl\to CuCl_2+H_2O\).

7) Non-metal oxide + base (example).

\(\displaystyle CO_2+2NaOH\to Na_2CO_3+H_2O\).

8) Bicarbonate + acid (example).

\(\displaystyle NaHCO_3+HCl\to NaCl+CO_2\uparrow+H_2O\).

9) Define concentrated vs dilute.

High vs low solute proportion in solution.

10) State pH ranges for acid/base.

Acid: <7; Base: >7; Neutral: 7.

11) Name two strong acids.

\(HCl, H_2SO_4\).

12) Name two strong bases.

\(NaOH, KOH\).

13) Why pure water is poor conductor?

Very low \([H^+]\) and \([OH^-]\) (~\(10^{-7}\) M each).

14) What happens to pH during neutralization?

Moves towards 7 as \(H^+\) and \(OH^-\) form \(H_2O\).

15) Acidic salt example with reason.

\(NH_4Cl\) (strong acid + weak base) → pH<7.

16) Basic salt example with reason.

\(Na_2CO_3\) (weak acid + strong base) → pH>7.

17) Write formula for washing soda (crystalline).

\(\displaystyle Na_2CO_3\cdot10H_2O\).

18) Name electrode where reduction occurs.

Cathode (gain of electrons).

19) Colour change of phenolphthalein in base.

Colourless → pink in basic solution.

20) Why are non-metal oxides acidic?

They form acids in water / react with bases to give salt + water.

1) Differentiate strong vs weak acid with equation.

Strong: near-complete ionization (e.g., \(HCl\to H^++Cl^-\)). Weak: partial (e.g., \(CH_3COOH \rightleftharpoons H^++CH_3COO^-\)).

2) Show neutralization using ionic equation.

\(\displaystyle H^+ + OH^- \to H_2O\); spectator ions form salt in solution.

3) Explain basicity and acidity with examples.

Basicity: \(H_2SO_4\) has 2 replaceable \(H^+\). Acidity: \(Ba(OH)_2\) gives 2 \(OH^-\) → dibasic base.

4) Write two reactions of acids with metals.

\(\displaystyle Zn+H_2SO_4(dil.)\to ZnSO_4+H_2\uparrow\); \(\displaystyle Mg+2HCl\to MgCl_2+H_2\uparrow\).

5) Why \(Al_2O_3\) and \(ZnO\) are amphoteric?

They react with acids and bases: \(Al_2O_3+6HCl\to 2AlCl_3+3H_2O\); \(Al_2O_3+2NaOH\to 2NaAlO_2+H_2O\).

6) Derive salt nature from parent acid/base strength.

Strong acid+strong base→neutral; Strong acid+weak base→acidic; Weak acid+strong base→basic.

7) Show carbonate/bicarbonate test with limewater.

\(\displaystyle Ca(OH)_2+CO_2\to CaCO_3\downarrow+H_2O\) (milky).

8) Compute molarity: 3.65 g HCl in 1 L.

\(M=\dfrac{m/M_r}{V}=\dfrac{3.65/36.5}{1}=0.1\ \text{M}\).

9) Why hydronium exists instead of bare \(H^+\)?

Free \(H^+\) binds to water: \(\displaystyle H^++H_2O\to H_3O^+\) for stability.

10) Write dissociation & conductivity link.

More ions → higher conductivity; strong electrolytes (salts, strong acids/bases) conduct well.

11) Explain universal indicator.

Mixed indicators giving a colour range mapped to pH 0–14 for quick estimation.

12) Balanced equations: metal oxides with acids.

\(\displaystyle Fe_2O_3+6HCl\to 2FeCl_3+3H_2O\); \(\displaystyle CaO+2HNO_3\to Ca(NO_3)_2+H_2O\).

13) Balanced: non-metal oxides with bases.

\(\displaystyle SO_3+2NaOH\to Na_2SO_4+H_2O\); \(\displaystyle CO_2+2KOH\to K_2CO_3+H_2O\).

14) Water of crystallization example & change on heating.

\(CuSO_4\cdot5H_2O \xrightarrow{\Delta} CuSO_4+5H_2O\) (blue→white), reversible on adding water.

15) Write net ionic for bicarbonate + acid.

\(\displaystyle HCO_3^-+H^+\to CO_2\uparrow+H_2O\).

16) Electrolysis of \(CuSO_4\): what changes at electrodes?

Cu deposits at cathode; anode dissolves (if copper) replenishing \(Cu^{2+}\).

17) Electrolysis of water: volume ratio & reasons.

\(H_2:O_2=2:1\) per stoichiometry of reactions at cathode/anode.

18) Define concentrated acid safely.

High solute fraction; always add acid to water, not vice versa.

19) Role of pH in daily life (two).

Soil suitability for crops; gastric juice pH for digestion.

20) Write two examples of salts and classify.

\(NaCl\) neutral; \(NH_4NO_3\) acidic; \(Na_2CO_3\) basic.

(a) Chloride, nitrate, hydride, ammonium

Odd: ammonium (\(NH_4^+\)) is a cation; others \(Cl^-, NO_3^-, H^-\) are anions.

(b) Hydrogen chloride, sodium hydroxide, calcium oxide, ammonia

Odd: sodium hydroxide (base/alkali); HCl (acid), CaO (basic oxide), NH\(_3\) (weak base) — by type, CaO is oxide not solution; best odd by “not a molecular gas/compound” is CaO (ionic solid).

(c) Acetic acid, carbonic acid, hydrochloric acid, nitric acid

Odd: acetic acid (weak); others strong mineral acids.

(d) Ammonium chloride, sodium chloride, potassium nitrate, sodium sulphate

Odd: ammonium chloride (acidic salt); others from strong acid + strong base (neutral).

(e) Sodium nitrate, sodium carbonate, sodium sulphate, sodium chloride

Odd: sodium carbonate (basic salt); others neutral.

(f) Calcium oxide, magnesium oxide, zinc oxide, sodium oxide

Odd: zinc oxide (amphoteric); others basic oxides.

(g) Crystalline blue vitriol, crystalline common salt, crystalline ferrous sulphate, crystalline sodium carbonate

Odd: common salt (NaCl) (no water of crystallization); others have water of crystallization (\(CuSO_4\cdot5H_2O\), \(FeSO_4\cdot7H_2O\), \(Na_2CO_3\cdot10H_2O\)).

(h) Sodium chloride, potassium hydroxide, acetic acid, sodium acetate

Odd: sodium chloride (neutral salt); others are base/acid/basic salt.

(a) Add 50 mL water to 50 mL \(CuSO_4\) solution.

Dilution: colour lightens; concentration (and thus intensity) decreases.

(b) Add phenolphthalein to 10 mL NaOH.

Turns pink (basic medium).

(c) Copper filings + dilute \(HNO_3\).

Effervescence/brown fumes (\(NO_2\)); blue solution of \(Cu^{2+}\) (e.g., \(Cu(NO_3)_2\)).

(d) Litmus into dil. HCl, then add conc. NaOH and stir.

Red in acid; on adding base, turns blue as pH > 7.

(e) \(MgO\) added to dil. HCl and to dil. NaOH.

With HCl: salt \(MgCl_2\) + water; with NaOH: little/no reaction (both basic).

(f) \(ZnO\) added to dil. HCl and to dil. NaOH.

With HCl: \(ZnCl_2+H_2O\); with NaOH: forms sodium zincate \(Na_2ZnO_2\) + water (amphoteric).

(g) Dilute HCl to limestone.

Effervescence of \(CO_2\): \(\displaystyle CaCO_3+2HCl\to CaCl_2+CO_2\uparrow+H_2O\).

(h) Heat blue vitriol; cool and add water.

Blue→white (loses \(5H_2O\)); on adding water, blue colour returns; physical change.

(i) Electrolytic cell with dilute \(H_2SO_4\).

Electrolysis of water: gases at electrodes; \(H_2\) at cathode (double volume of \(O_2\) at anode).

List: \(CaO, MgO, CO_2, SO_3, Na_2O, ZnO, Al_2O_3, Fe_2O_3\)

Basic: \(CaO, MgO, Na_2O, Fe_2O_3\).
Acidic: \(CO_2, SO_3\).
Amphoteric: \(ZnO, Al_2O_3\).

a) Formation of NaCl from Na and Cl

Na (2,8,1) → loses 1e\(^{-}\) → \(Na^+\) (2,8); Cl (2,8,7) + 1e\(^{-}\) → \(Cl^-\) (2,8,8); electrostatic attraction forms NaCl.

b) Formation of MgCl\(_2\) from Mg and Cl

Mg (2,8,2) → loses 2e\(^{-}\) → \(Mg^{2+}\); two Cl atoms each gain 1e\(^{-}\) → 2 \(Cl^-\); compound \(MgCl_2\).

List: HCl, NaCl, KOH, NH\(_3\) (aq), CH\(_3\)COOH, MgCl\(_2\), CuSO\(_4\)

\(HCl\to H^++Cl^-\) (large/strong).
\(NaCl\to Na^++Cl^-\) (large).
\(KOH\to K^++OH^-\) (large).
\(NH_3+H_2O \rightleftharpoons NH_4^++OH^-\) (small/weak).
\(CH_3COOH \rightleftharpoons H^++CH_3COO^-\) (small/weak).
\(MgCl_2\to Mg^{2+}+2Cl^-\) (large).
\(CuSO_4\to Cu^{2+}+SO_4^{2-}\) (large).

a) 7.3 g HCl in 100 mL solution

g/L: \(7.3/0.1=73\ g/L\). \(M=\dfrac{7.3/36.5}{0.1}=2.0\ M\).

b) 2 g NaOH in 50 mL solution

g/L: \(2/0.05=40\ g/L\). \(M=\dfrac{2/40}{0.05}=1.0\ M\).

c) 3 g \(CH_3COOH\) in 100 mL

g/L: \(30\ g/L\). \(M=\dfrac{3/60}{0.1}=0.5\ M\).

d) 4.9 g \(H_2SO_4\) in 200 mL

g/L: \(4.9/0.2=24.5\ g/L\). \(M=\dfrac{4.9/98}{0.2}=0.25\ M\).

Measure pH & explain effect

Typical fresh rain pH ≈ 5.6 (due to dissolved \(CO_2\)); acid rain pH < 5.6 harms plants, aquatic life, and corrodes structures.

a) Classify acids by basicity with one example each

Monobasic: \(HCl\); Dibasic: \(H_2SO_4\); Tribasic: \(H_3PO_4\).

b) What is neutralization? Two daily life examples

Acid + base → salt + water; examples: antacid neutralizes excess stomach acid; lime (Ca(OH)\(_2\)) treats acidic soil.

c) Explain electrolysis of water with electrode reactions

Using electrolyte, current splits water: Cathode \(2H_2O+2e^- \to H_2+2OH^-\); Anode \(2H_2O \to O_2+4H^++4e^-\); gas ratio \(2:1\).

a) Hydronium ions are always in form \(H_3O^+\)

Bare \(H^+\) is highly reactive; immediately associates with water to form \(H_3O^+\).

b) Buttermilk spoils in copper/brass container

Acidic buttermilk reacts with metal to form salts; possible contamination and corrosion—unsafe.

(a) \(NaOH\) added to \(HCl\)

\(\displaystyle NaOH+HCl\to NaCl+H_2O\).

(b) Zinc dust + dilute \(H_2SO_4\)

\(\displaystyle Zn+H_2SO_4(dil.)\to ZnSO_4+H_2\uparrow\).

(c) Dilute \(HNO_3\) + calcium oxide

\(\displaystyle CaO+2HNO_3\to Ca(NO_3)_2+H_2O\).

(e) \(CO_2\) through \(KOH\) solution

\(\displaystyle CO_2+2KOH\to K_2CO_3+H_2O\).

(f) Dilute \(HCl\) on baking soda

\(\displaystyle NaHCO_3+HCl\to NaCl+CO_2\uparrow+H_2O\).

a) Acids vs Bases

Acids give \(H^+\), turn blue litmus red, pH<7; Bases give \(OH^-\), turn red litmus blue, pH>7.

b) Cation vs Anion

Cation: positively charged ion (\(Na^+\)); Anion: negatively charged ion (\(Cl^-\)).

c) Negative vs Positive electrode

Cathode (negative): reduction; Anode (positive): oxidation (in electrolytic cell).

Substances: common salt, sodium acetate, HCl, \(CO_2\), KBr, \(Ca(OH)_2\), \(NH_4Cl\), vinegar, \(Na_2CO_3\), ammonia, \(SO_2\)

pH ≈ 7 (neutral salts): NaCl, KBr.
pH < 7 (acidic): HCl, \(NH_4Cl\), vinegar (acetic acid), \(CO_2\) (acidic solution), \(SO_2\) (acidic solution).
pH > 7 (basic): sodium acetate, \(Ca(OH)_2\), \(Na_2CO_3\), ammonia solution.

Neutralization patterns (complete the typical forms)

\(\displaystyle HNO_3 + KOH \to KNO_3 + H_2O\).
\(\displaystyle 2NH_4OH + H_2SO_4 \to (NH_4)_2SO_4 + 2H_2O\).
\(\displaystyle HBr + KOH \to KBr + H_2O\).

Acids with metals

\(\displaystyle Mg+2HCl \to MgCl_2+H_2\uparrow\).
\(\displaystyle Zn+H_2SO_4(dil.) \to ZnSO_4+H_2\uparrow\).
(Copper requires oxidizing acids like \(HNO_3\); with dil. HCl no reaction.)

Metal oxides with acids (basic oxides)

\(\displaystyle CaO+2HCl \to CaCl_2+H_2O\).
\(\displaystyle MgO+2HCl \to MgCl_2+H_2O\).
\(\displaystyle ZnO+2HCl \to ZnCl_2+H_2O\).
\(\displaystyle Al_2O_3 + 6HF \to 2AlF_3 + 3H_2O\).

Non-metal oxides with bases (acidic oxides)

\(\displaystyle CO_2+2NaOH \to Na_2CO_3+H_2O\).
\(\displaystyle CO_2+2KOH \to K_2CO_3+H_2O\).
\(\displaystyle SO_3+2NaOH \to Na_2SO_4+H_2O\).

Carbonates/Bicarbonates with acids

\(\displaystyle Na_2CO_3+2HCl \to 2NaCl+CO_2\uparrow+H_2O\).
\(\displaystyle Na_2CO_3+H_2SO_4 \to Na_2SO_4+CO_2\uparrow+H_2O\).
\(\displaystyle CaCO_3+2HNO_3 \to Ca(NO_3)_2+CO_2\uparrow+H_2O\).
\(\displaystyle K_2CO_3+H_2SO_4 \to K_2SO_4+CO_2\uparrow+H_2O\).
\(\displaystyle NaHCO_3+HCl \to NaCl+CO_2\uparrow+H_2O\).
\(\displaystyle KHCO_3+HNO_3 \to KNO_3+CO_2\uparrow+H_2O\).
\(\displaystyle NaHCO_3+CH_3COOH \to CH_3COONa+CO_2\uparrow+H_2O\).

Solute	Given	g/L	Molar Mass (g/mol)	Molarity (mol/L)
HCl	3.65 g in 1 L	3.65	36.5	\(0.10\)
NaOH	1.5 mol in 2 L	—	40	\(0.75\)
NaCl	117 g in 2 L	58.5	58.5	\(1.00\)