Question

As avea mai mare nevoie de formule, decat de rezultate.

Answer 1

3. ms = ?  (g) H2SO4
C = 50%
Vs = 4L sol. H2SO4
Cm = 0,5 moli/L

Cm = md/M*Vs(L) sau Cm = n/Vs 

Cm = md/M*Vs(L) => md = Cm*M*Vs(L)  = 0,5*98*4 = 196g H2SO4

Cm = n/Vs -> n = Cm*Vs = 0,5*4 = 2 moli H2SO4

md = 2*98 = 196g H2SO4    ,   MH2SO4 = 98g/mol

C = md/ms*100 => ms=md*100/C = 196*100/50 = 392g

4.a. pH = 12

[H₃O⁺] = ?

[H₃O⁺] = 10⁻(pH) = 10⁻¹² moli/L

b. HCO₃⁻ +  H₂O ⇔ CO₃⁻² + H₃O⁺ 

HCO₃⁻ / CO₃⁻ ² (baza conjugata)

5.a. Ionii prezenti : Cu²⁺ ; SO₄²⁻, H⁺, OH⁻

A(+) OH⁻ -1e⁻ => OH
2OH ⇒ H₂O + 1/2O₂↑

K(-) Cu⁺² +2e⁻ ⇒ Cu⁰

In solutie : 2H⁺ + SO₄²⁻ => H₂SO₄

Rc globala: CuSO₄ + H₂O ---(electroliza)---> Cu + H₂SO₄ + 1/2O₂↑

b. m Cu = ?

m CuSO₄ = 320g

η = 80%

M CuSO₄ = 160g/mol

n CuSO4 = 320/160 = 2 moli


n CuSO₄ = n Cu = 2 moli (nt)

η = np/nt*100 => np = η*nt/100 = 80*2/100 = 1,6 moli Cu

n=m/M => m Cu = 1,6*64 = 102,4g