Question

CHIMIE.
1.Calculeaza pH-ul unei solutii obtinute prin amestecarea a 600mL solutie NaOH 0,005M cu 400mL solutie cu HCL 0,005M
2.Care este pH-ul solutiei care contine in 500 ML , 1,825 g HCl.
Multumesc anticipat! Imi trb urgent!

Answer 1

1. pH = ?

V1 = 600mL = 0,6 L NaOH
C1 = 0,005M
V2 = 400mL = 0,4L HCl
C2 = 0,005M

C1 = n1/V1 => n1 = C1*V1 = 0,005*0,6 = 0,003 moli NaOH
C2 = n2/V2 => n2 = C2*V2 = 0,005*0,4 = 0,002 moli HCl

n NaOH exces = 0,001 moli

V final = 1000mL = 1L

C final = n NaOH exces/V final = 0,001/1 = 10⁻³ M 

[OH⁻] = C final = 10^(-pOH) = 10⁻³M => pOH = 3

pH = 11 

2. pH = ?

V = 500mL
m = 1,825g HCl

C = md/M*Vs = 1,825/36,5*0,5 = 0,1M

HCl -> A.T => [HCl] = C = [H₃O⁺] = 10^(-pH) = 10⁻¹M => pH = 1