3.
2Na + 2H2O --> 2NaOH + H2
CaO + H2O --> Ca(OH)2
2NaOH + CuSO4 --> Cu(OH)2 + Na2SO4
2NaCl + 2H2O --electroliza--> 2NaOH + H2 + Cl2
4.
CaO + H2O --> Ca(OH)2 , varul aplicat pe perete se intareste in timp datorita pierderii de apa astfel ca Ca(OH)2 se va transforma in mare parte in CaO
Ca(OH)2 ---> CaO + H2O
5.
84 g md n moli
3KOH + AlCl3 --> 3KCl + Al(OH)3
3x56 133,5 1
=> n = 84x1/3x56 = 0,5 moli baza
=> md = 84x133,5/3x56 = 66,75 g AlCl3 reactionata
stim ca c% = mdx100/ms
=> ms = mdx100/c%
= 66,75x100/10 = 667,5 g sol. AlCl3
6.
a.
Al(OH)3 + 3HCl --> AlCl3 + 3H2O
b.
2,5 g m g
Al(OH)3 + 3HCl --> AlCl3 + 3H2O
78 3x36,5
=> m = 2,5x3x36,5/78 = 3,51 g HCl
c.
100% suc gastric ......................... 0,3% HCl
a g .................................................. 3,51g HCl
= 1170 g suc. gastric
7.
Ce mase de solutii ( ms1 si ms2) sunt necesare pentru a obtine solutie finala de cf% = 45%, msf = 2000 grame solutie de 45%, prin amestecarea unei solutii de c1= 90% cu o solutie de c2 = 10 %.
Rezolvare:
metoda grafica (regula dreptunghiului)
c1=90% -----------------> c.f.-c2 = 45-10= 35 parti masa sol. 90%
c.f.=45%
c2=10% -------------------> c1-c.f= 90-45= 45 parti masa sol. 10%
------------------------------------------------
total = 35+45= 80 parti sol. finala
80 parti sol. finala ............. 35 parti sol. 90% .............. 45 parti sol. 10%
2000 g ..................................... ms1 g ............................... ms2 g
= 875 g sol 90% = 1125 parti sol 10%
