Question

Calculati, la 250C:
a. Concentratia [H+] si pH pentru o proba de apa potabila care contine [OH]=2.0X10-7M
b. Concentratiile [H+] si [OH-] ale sangelui uman la pH=7,40
c. pOH pentru o solutie in care [H+]=5x[OH-]

Answer 1

cred ca t=25C ????????

a.     [H⁺][OH⁻]= 10⁻¹⁴mol²/l²

----> [H⁺]= 10⁻¹⁴/2x10⁻⁷mol/l=0,5x10⁻⁷mol/l=5x10⁻⁸mol/l

b.pH=- lg[H⁺]----> [H⁺]= 10la puterea (-7,4)= 3,98x10⁻⁸mol/l

                            [OH⁻]= 10⁻¹⁴/3,98X10⁻⁸ mol/l=0,25x10⁻⁶mol/l=           2,5x10⁻⁷mol/l

c. 5[OH⁻][OH⁻]=10⁻¹⁴mol²/l²---> [OH⁻]²=0,2X10⁻¹⁴---> [OH⁻]=0,44x10⁻⁷mol/l

pOH= -lg(4,4x10⁻⁷)= 7-lg4,4=..................calculeaza !!!!!