Question

6. What ion gives H2SO the ability to react strongly with many substances? What ion is responsible for the corro- of bases like NaOH? siveness strong 7. List four common properties of acids and four common properties of bases.

Answer 1

6. The H₂SO₄ ionization is two step process to generate protons (2H⁺) and sulphate ions (SO4^--)

Step 1 :  H₂SO₄ + H₂O   $\rightarrow$ H₃O⁺   + HSO4^-

Step 2:  HSO4^- $\rightarrow$ H⁺   + SO4^--

Therefore the conjugate acid ions hydronium ion (H₃O+) and (H+) has ability to react with many substance, when react vigorously with NaOH, The overall reaction is called the neutralization reaction in which the acid reacts with base resulting the carrosiveness of base and forms the salt and water. The balanced equation is as below.

    2H₂SO₄ + 2NaOH $\rightarrow$ Na₂SO₄ + 2H₂O

7. The common properties of acid and base are,

a) By Arrhenius theory, the acids give off H⁺ (hydrogen) ions when ionizes in water and bases give off OH^- (hydroxide) ions  when ionizes in water..

b) As per the Brønsted-Lowry the acid is proton or hydrogen (H⁺) donor and base is called the proton or hydrogen (H⁺) acceptor.

c) By Lewis acid base concept, the acid called an electrons acceptor and base donate the electrons.

d)  Acids taste sour, react with metals and carbonates which turn blue litmus paper into red in solution. Bases taste bitter, do not react with carbonates and turn red litmus paper blue in solution.

8. The particles in pure water in chemistry means pure H₂O without any dissolved salts or gases called deionized water.

In pure drinking water as per WHO standards, has traces of minerals like sodium, magnesium, traces of carbonates and dissolved gases like oxygen.

Normally purified liquid water consists of a mixture of molecules and ions, including H₂O, HDO (≈ 10^-2 %), H₃O⁺ and OH^- (≈ 10^-6 %), H₂O₂ (≈ 10^-7 %), CO₂ (≈ 10^-4 %), O₂ (≈ 10^-4 %) and N₂ (≈ 10^-3 %)

9. The water reaction with itself is also called the self ionization or autoionization of water as below equation,

H₂O + H₂O   $\rightarrow$ H₃O⁺   + OH^-

The equilibrium constant for the autoionization of water is K_eq

$Keq = [H3O+] [OH-]/[H2O] [H2O] = [H+] [OH-]/[H2O]$

As in dilute solution concentration of water is 1

Keq = [H⁺] [OH^-]

The equilibrium constant for self ionization of water = 10 ^-14 at room temperature (25 ⁰C) The ionization constant or dissociation constant or self-ionization constant or water ion-product constant or ionic product of water is denoted as K_w which is same as Keq.

Keq = Kw = [H⁺] [OH^-] = 10 ^-14

pH + pOH = 14

10. Water molecules can acts either acids or bases as per the Brønsted-Lowry concept therefore water has an amphoteric nature.