2.
+2 0 0 +1
NiO + H2 --> Ni + H2O
Ni⁺²_+2e-__> Ni⁰ reducere (ag ox) NiO
H2⁰_-2e-__> H2⁺ ox (ag. red) H2
+2 0 0 +2
CuO + C --> Cu + CO
Cu⁺²_+2e-__> Cu⁰ red. (ag. ox) CuO
C⁰_-2e-__> C⁺² ox (ag. red) C
+5 0 +3 0
V2O5 + Al --> Al2O3 + V
6x V2⁺⁵_+10e-__> 2V⁰ red (ag. ox) V2O5
10x 2Al⁰_-6e-__> Al2⁺³ ox (ag red) Al
=>
3V2O5 + 10Al --> 5Al2O3 + 6V
6.
a)
+5 -1 -1 0
KClO3 + HCl --> KCl + H2O + Cl2
1x Cl⁺⁵_+6e-__> Cl⁻ red (ag ox) KClO3
3x 2Cl⁻¹_-2e-_> Cl2⁰ ox. (ag red) HCl
=> prin oxidarea HCl
b)
KClO3 + 6HCl --> KCl + 3H2O + 3Cl2
c)
100% KClO3.......................... 2,5 impur
98% ....................................... a = 2,25 pur
2,25 g n moli
KClO3 + 6HCl --> KCl + 3H2O + 3Cl2
122,5 3
=> n = 2,25x3/122,5 = 0,055 moli Cl2
d)
2,25 g md g
KClO3 + 6HCl --> KCl + 3H2O + 3Cl2
122,5 6x36,5
=> md = 2,25x6x36,5/122,5
= 4,02 g HCl
stim ca c% = mdx100/ms
=> ms = mdx100/c%
= 4,02x100/36 = 11,17 g sol HCl
stim ca ro = ms/Vs
=> Vs = ms/ro
= 11,17/1,183 = 9,45 cm3 sol. HCl
