Question

Calculati pH-ul unei solutii care contine 0,4 g NaOH in 100 cm3

Answer 1

-calculez moli NaOH ,cu M= 40g/mol
n sau niu= 0,4g/40g/mol= 0,01mol   NaOH
- calculez moli din 1000ml solutie(1ml=1cm³)
n= 0,01x10==> 0,1mol---> c,m= n/V--> C= 0,1mol/litru=10 ⁻¹mol/l
-NaOh este o baza tare, total ionizata, si se aproximeaza [OH⁻] =[NaOH}
-stiu :[OH⁻]x[H⁺] =10 ⁻¹⁴mol2/l2---> [H⁺]= 10⁻¹³mol/l  
-pH= - Lg[H⁺]----> pH= 13---. > SOLUTIE ALCALINA