Larutan H2SO4 0,4% (Mr = 98) dengan massa jenis 1,225 gram/cm kubik, berapa PH?

Diketahui :
H2SO4 = 0,4%
Mr = 98 gr/mol
Massa jenis (p) = 1,225 gram/cm³ = 1,225 gram/ml

Ditanya : pH larutan ?

Jawab :

H2SO4 :
= 0,4%
= 0,4 gram H2SO4 / 100 gram larutan

Volume larutan :
= m / p
= 100 gram / 1,225 gram/ml
= 81,63 ml

Molaritas H2SO4 :
= gr / Mr × 1000 / Vml
= 0,4 / 98 × 1000 / 81,63
= 0,05 M

[H+] :
= a . M
= 2 . 0,05 M
= 10-¹ M

pH :
= – log [H+]
= – log 10-¹
= 1