Question

1.Cati atomi de oxigen (O) se gasesc in 212 kg Na2Co3?

2. Calculati masa de oxigen (O) din 572 g solutie de Na2Co3 de concentratie 37%.

Se dau:
ANa=23
AO=16
AC=12
AH=1

Answer 1

1.   Na2CO3
 
MNa2CO3 =2.23 +12 +3.16 =106

Daca in 106kgNa2CO3 se gasesc 48kg O  atunci in 212kg  Na2CO3 se afla xkg O


106KgNa2CO3-------------48kg O
212kgNa2CO3--------------Xkg O

X=212.48/106=96kg O


AO=16                              23
16g O----------------6,023.10   atomi O
96gO-----------------Y

                      23                        23
Y=96.6,023.10    /16 =36,138.10    atomi O


2. Se calculeaza masa subst.dizolvate md din formula concentratiei c

c=md/ms . 100
md=c.ms/100
md=37.572/100=211,64 g Na2CO3

MNa2CO3=106

106 gNa2CO3------------48gO
211,64 gNa2CO3-------X

X=211,64.48/106=95,82 g O