Question

8. Calculaţi echivalentul-gram pentru:
Na; Al; SO2; Al2O3; HCl; H3PO4; Ca(OH)2; Al(OH)3; CuSO4; Al2(SO4)3; HNO3;
KOH; Ba(OH)2; Fe(OH)3; MgO; Fe2O3.

Answer 1

Răspuns:

• Echivalentul gram  (Eg) la substantele simple( elemente chimice) se calculeaza cu relatia :

E g atom = Masa atomica, A / valenta

***

Eg Na= 23 g/1 = 23g

Eg Al = 27 g / 3 = 9 g

• Echivalentul gram (Eg) la substantele compuse - oxizi se calculeaza cu relatia:

E g Oxizi = Masa molara, M / numar atomi metal (nemetal) x valenta lui

***

Eg SO₂ = M SO₂/ 1.4= AS+2.A O / 4 =32+2.16/4=64/4=16 g

Eg Al₂O₃=M Al₂O₃ / 2.3= (2.A Al+3.A O)/6=(2.27+3.16)/6=102/6=17 g

Eg MgO= M MgO/1.2=(A Mg + A O) /1. 2= (24+16) / 2=40/2=20 g

Eg Fe₂O₃= M Fe₂O₃ / 2.3= (2. A Fe + 3. A O) /6=(2.56+3.16)/6=160/6=26,67 g

• Echivalentul gram  (Eg) la baze (hidroxizi) se calculeaza cu relatia:

Eg baze =Masa molara / numarul de grupari HO⁻ (aciditate)

***

Eg Ca(OH)₂=M Ca(OH)₂/ 2= (A Ca+2.A O+2.A H) / 2=(40+2.16+2.1)/2=74/2=37 g

Eg Al(OH)₃= M Al(OH)₃/3 = (A Al + 3.A O +3.A H)/3=(27+3.16+3.1)/3=26g

Eg KOH = M KOH/1= (A K+ A O+A H)/1= (39+16+1)/1=56g

Eg Ba(OH)2=M Ba(OH)₂/2= (A Ba+ 2.A O+ 2. A H) /2= (137+2.16+2.1)/2=

171/2=85,5 g

Eg Fe(OH)₃ = M Fe(OH)₃/ 3 = (A Fe + 3. A O + 3.A H) / 3= (56+3.16+3.1)/3=

107/3=35,67 g

• Echivalentul gram (Eg) la acizi se calculeaza cu relatia:

Eg acizi = Masa molara/ numarul de ioni H⁺ (bazicitate)

***

Eg HCl = M HCl/ 1= A H + A Cl = 1+35,5=36,5 g

Eg H₃PO₄ = M H₃PO₄/3= (3.A H + A P +4.A O)/ 3= (3.1+31+4.16)/3=98/3=32,67 g

Eg HNO₃ = M HNO₃/ 1 = A H+ A N + 3.A O= 1+14+3.16=63 g

• Echivalentul gram (Eg) la saruri se calculeaza cu relatia:

Eg sare= Masa molara/ numarul de metal.valenta metal

***

Eg CuSO₄ = M CuSO4 / 1.2= (A Cu + A S + 4.A O)/2= (64+32+4.16)/2=160/2=80 g

Eg Al₂(SO₄)₃= M Al₂(SO₄)₃ / 2.3 = (2.A Al + 3A S+ 12 A O)/6= (2.27+3.32+12.16)/6=342/6=57 g

Verificati, calculele! Sper, sa va ajute!

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