chem- acids and bases

Q.1 Which has higher H+ concentration: 1M HCl or 1M CH3COOH?

HCl

Q.2 Why is CH3COOH a weak acid and HCl a strong acid?

HCl fully ionizes in water; CH3COOH only partially ionizes.

Q.3 Which gas evolves when dilute HCl reacts with metal bicarbonate? How is it recognized?

CO2 gas; turns lime water milky.

Q.4 Effect of increase in H+ ion concentration on pH?

pH decreases.

Q.5 Name the gas when dilute HCl reacts with active metal. How recognized?

Hydrogen gas; pop sound with burning splint.

Q.6 Why tooth decay starts when pH < 5.5?

Enamel dissolves in acid, starts decay.

Q.7 What happens to pH of acid when diluted?

pH increases.

Q.8 Fresh milk pH=6 turns to curd; pH increases or decreases? Why?

Decreases; lactic acid forms during curdling.

Q.9 Arrange pH 0,2,4,6 by increasing H+ concentration.

6 < 4 < 2 < 0 (lowest to highest H+).

Q.10 Why acid rain harms aquatic life?

Lowers pH of water; harmful for organisms.

Q.11 Heating CuSO4 crystals: color before and after; source of droplets?

Blue before heating, white after; droplets are water of crystallisation.

Q.12 Products when NaHCO3 heated and chemical equation?

Na2CO3, H2O, CO2; 2 NaHCO3 → Na2CO3 + H2O + CO2.

Q.13 Name & formula of calcium compound to disinfect water; how manufactured?

Bleaching powder (Ca(OCl)2); made by passing Cl2 over dry slaked lime.

Q.14 Decomposition of gypsum to P.O.P and back.

CaSO4·2H2O → CaSO4·½H2O + 1½ H2O; then +1½ H2O → back to CaSO4·2H2O.

Q.15 CO2 passed into lime water (a) limited (b) excess.

(a) Milkiness (CaCO3); (b) milkiness disappears (Ca(HCO3)2).

Q.16 (a) Why bleaching powder smells of chlorine? (b) Why not dissolve fully?

(a) Releases Cl2 gas; (b) has insoluble Ca(OH)2.

Q.17 Formula of washing soda, from baking soda, uses?

Na2CO3·10H2O; heat NaHCO3; used to soften water, make glass & soap.

Q.18 Difference: litmus vs universal indicator; synthetic vs natural indicators.

Litmus shows acid/base; universal shows pH scale; synthetic made in lab; natural from plants.

Q.19 (a) Zinc + NaOH (b) Zinc + HCl.

(a) Sodium zincate + H2; (b) ZnCl2 + H2.

Q.20 Two characteristics of acids and bases.

Acids: sour, turn blue litmus red; Bases: bitter, turn red litmus blue.

Q.21 Explain chlor-alkali process.

Pass electricity through brine → Cl2, H2, NaOH; called chlor (chlorine) + alkali (NaOH).

Q.22 Why: (a) don’t add water to concentrated acid (b) use antacids (c) baking soda on bee sting.

(a) Heat splashes acid; (b) neutralizes excess acid; (c) neutralizes formic acid.

Q.23 What is water of crystallisation of Four salts? Why P.O.P is CaSO4·½H2O?

Water in crystals; CuSO4·5H2O, FeSO4·7H2O, Na2CO3·10H2O, MgSO4·7H2O; P.O.P has half water.

Q.24 Why NaHCO3 in fire extinguisher & baking powder?

Releases CO2; puts out fire & makes dough rise.

Q.25 Why: (a) tartaric acid in baking powder (b) bleaching powder disinfects water (c) strong acid ≠ concentrated acid.

(a) Stops bitter taste; (b) releases Cl2; (c) strong = fully ionizes; concentrated = high amount per volume.