Question

cati moli de apa se gasesc in 90 g apa

Answer 1

m=90 g $H_{2}O$

$M_{H_{2}O}=2\cdot 1+16=2+16=18$

n=$\dfrac{m}{M}$

n= $\dfrac{90}{18}$=5 moli

Answer 2

v(cantitatea de substanta) =m ÷M(masa molară)
M(apei) =18g/mol
v=90g÷18g/mol=5mol
v(apa)=5mol
Succes!!!