Răspuns:
Explicație:
a. H3PO4
M= 3 +31 +4.16=98 ------> 98g/moli
98g H3PO4--------3gH--------31gP-------64g O
100g-----------------------x--------------y-----------z
x= 100 . 3 : 98 = 3,06% H
y= 100 . 31 : 98 = 31,63%P
z= 100 . 64 : 98 = 65,31% O
b . NaOH
M= 23 +16 +1=40-------> 40g/moli
40g NaOH ------23g Na--------16gO--------1gH
100g---------------------x-------------y----------------z
x= 100. 23 : 40= 57,5% Na
y= 100. 16 : 40=40% O
z= 100.1 : 40=2,5% H
