Equilibrium 3

Question 1

Lewis acid base concept

Answer 1

According to this acid is a substance which accepts lone pair of electron and base is a substance which donates a lone pair of electron.

Question 2

lewis acids

Answer 2

• All positively charged ions are Lewis acids
  eg: - NH4+, H3O+, Cl-, NO+
• All neutral species having electron deficiency octet.
  eg: - BF3, Bcl3, AlCl3
• All compounds in which central atom has a vacant d orbital which can accept electrons.
  eg: - SF4, SiCl4
• All molecules having double bond between two elements with different electronegativities.
  Eg: - O=C=O
  O=S=O

Question 3

Lewis base

Answer 3

• all negatively charged species.
  eg: - Cl-, OH-, F-, CN-, Br-
• all neutral charged having lone pair of electron
  eg: - NH3, H2O, R-O-R

Question 4

Write a description on ionic product of water

Answer 4

• Ionic product of water kw is defined as the product of concentration of hydronium ions to the concentration of hydroxyl ions.
• It has a constant value, if temperature is constant at 298 Kelvin (room temperature ) the value is 1 x 10 ⁻¹⁴ moles/L
• Kw= x.x = x²
  x= √10 ⁻¹⁴
  = 10⁻⁷
  [H3O+] = [OH-] = 10⁻⁷ mol/L

Question 5

derivation of pH formula

Answer 5

[H+] = 10 ^-pH
log [H+]=log 10 ^-pH
log[H+]= -pH log 10
log[H+] = -pH
pH= -log [H+]

Question 6

Define pH

Answer 6

p H is defined as the negative logarithm of hydrogen ion concentration in a solution.

Question 7

derivation of pOH formula

Answer 7

Kw= [H+] [OH-]
log Kw= log ([H+] [OH-])
log Kw= (log [H+]) + (log [OH-])
- log Kw= -(log [H+]) - (log [OH-])

pKw= pH+ pOH
=> pKw= pH+ pOH=14

Question 8

define indicators

Answer 8

Indicators are organic substances which are weak acids or weak base which change the color in a certain phrase range.

Question 9

how to detect the endpoint of a titration

Answer 9

indicators are used to detect the endpoint in an acid based titration.