1. Dry HCl gas does not contain $H^+$ ions. It requires water to dissociate
and release $H^+$ ions which are responsible for acidic behaviour.
2. Dilution of acid is highly exothermic. If water is added to acid, the heat
generated can cause the mixture to splash out, causing burns. Adding acid to water allows the large volume
of water to absorb the heat safely.
3. Acids dissociate in water to produce $H^+$ (or $H_3O^+$) ions which are
mobile charge carriers, enabling electrical conductivity.
4. Alcohol and glucose have hydrogen in their molecules, but their hydrogen
is not ionizable. They do not release $H^+$ ions in aqueous solution.
5. Yes, from dissociation of water. But the concentration of $OH^-$ ions is
much greater than $H^+$ ions, making it basic.
6. When soil is too acidic (low pH). Quick lime or slaked lime neutralises
the excess acidity of the soil.
7. Baking soda ($NaHCO_3$) releases $CO_2$ when heated, but also produces
$Na_2CO_3$ which tastes bitter. Tartaric acid neutralises the bitter taste of $Na_2CO_3$.
8. Plaster of Paris absorbs moisture (water) from air and sets into a hard
mass (Gypsum), becoming unusable for moulding.
9. Distilled water has no dissolved ions to carry current. Rain water
dissolves gases like $CO_2$ and $SO_2$ forming acids, providing ions for conduction.
10. pH will decrease (become more acidic). Lactobacillus bacteria convert
lactose in milk to Lactic Acid during curd formation.
11.
$Zn(s) + H_2SO_4(aq) \rightarrow ZnSO_4(aq) + H_2(g)$
12. (Amphoteric nature of Zn)
$Zn(s) + 2NaOH(aq) \rightarrow Na_2ZnO_2(aq) + H_2(g)$
13.
$CaCO_3(s) + 2HCl(aq) \rightarrow CaCl_2(aq) + H_2O(l) + CO_2(g)$
14.
$Na_2CO_3(s) + 2HCl(aq) \rightarrow 2NaCl(aq) + H_2O(l) + CO_2(g)$
15. (Excess $CO_2$)
$Ca(OH)_2(aq) + CO_2(g) \rightarrow CaCO_3(s) + H_2O(l)$ (Milky)
$CaCO_3(s) + H_2O(l) + CO_2(g) \rightarrow Ca(HCO_3)_2(aq)$ (Clear)
16.
$CuO(s) + 2HCl(aq) \rightarrow CuCl_2(aq) + H_2O(l)$
(Black CuO turns blue-green $CuCl_2$)
17. (Neutralisation)
$NaOH(aq) + HCl(aq) \rightarrow NaCl(aq) + H_2O(l)$
18.
$2NaHCO_3(s) \xrightarrow{\Delta} Na_2CO_3(s) + H_2O(g) + CO_2(g)$
19.
$Ca(OH)_2(s) + Cl_2(g) \rightarrow CaOCl_2(s) + H_2O(l)$
20.
$Na_2CO_3(s) + 10H_2O(l) \rightarrow Na_2CO_3 \cdot 10H_2O(s)$
21.
$CaSO_4 \cdot \frac{1}{2}H_2O(s) + \frac{3}{2}H_2O(l) \rightarrow CaSO_4 \cdot
2H_2O(s)$
22. Bleaching Powder ($CaOCl_2$)
23. Plaster of Paris ($CaSO_4 \cdot \frac{1}{2}H_2O$)
24. Washing Soda ($Na_2CO_3 \cdot 10H_2O$)
25. Baking Soda ($NaHCO_3$)
26. Baking Soda ($NaHCO_3$)
27. Washing Soda ($Na_2CO_3$)
28. Baking Soda ($NaHCO_3$) or Milk of Magnesia
($Mg(OH)_2$)
29. Plaster of Paris
30. Washing Soda
31. Bleaching Powder ($CaOCl_2$)
32. Bee sting injects Formic Acid (Methanoic Acid). Baking soda (mild base)
neutralises the acid, giving relief.
33. Nettle stings inject Formic Acid. Rubbing the affected area with leaves
of a Dock plant (which contain a base) provides relief.
34. In moist air, Copper reacts with $CO_2$, $O_2$ and moisture to form basic
copper carbonate, $CuCO_3 \cdot Cu(OH)_2$, which is green.
35. Baking soda is a mild base. It slightly increases the pH, slowing down
the growth of Lactobacillus bacteria and delaying curd formation. It also keeps milk fresh longer.
