Question

va rog ajutorrrr
am test

Answer 1

Răspuns:

Explicație:

1.

4moli H2SO4

react. cu 4moli NaOH

subst. in exces

xmoli             4moli    

H2SO4  +2 NaOH = Na2SO4 + 2H2O

1mol         2moli          

x= 4 : 2= 2moli H2SO4

Deci H2SO4 este in exces -----> 4moli - 2moli= 2moli H2 SO4 in exces

2.

400g sol. NaOH , c=5%

react. cu HCl

masa de HCl

moli sare

md NaOH= c. ms : 100

md=5 . 400 : 100=20g NaOH

20g          xg      yg

NaOH + HCl  = NaCl + H2 O

40g       36,5g   58,5g

x= 20 . 36,5 : 40= 18,75 g HCl

n= m : M

n= 18,75g : 36,5g/moli= 0,5moli HCl

y=20. 58,5 : 40=29,25g NaCl

n= 29,25g : 58,5g/moli=0,5moli NaCl

M NaCl= 23 + 35,5=58,5----> 58,5g/moli

MNaOH= 23 + 16 +1 = 40---> 40g/moli