DIKET :

V (NH4)Cl = 100 mL

pH = 9

Kb atau Ionisasi basa atau tetapan basa NH3 = 10^-5

DITANYA : Berapa massa

( gram ) kristal dari Senyawa (NH4)Cl yang harus di masukan ?

JAWAB :

pOH = 14 - (-Log [OH-])

pOH = 14 - (5-Log1)

pOH = 9

[OH-]

-Log [OH-] = pOH

-Log [OH-] = 5

-Log [OH-] = -Log 10^-5

[OH-] = 10^-5

n Basa NH3 :

= M . V

= 10^-5 × 100 mL

= 0,00005 × 100 mL

= 0,005 mol

n garam (NH4)Cl :

= Kb . n Basa / [OH-]

= 10^-5 × 0,005 / 10^-5

= 0,005 mol

Mr (NH4)Cl :

= Ar N + (Ar H × 4) + Ar Cl

= 14 g/mol + (4 g/mol) + 35,5 g/mol

= 53,5 g/mol

Gram (NH4)Cl :

= n garam (NH4)Cl . Mr (NH4)Cl

= 0,005 mol × 53,5 g/mol

= 0,2675 gram