Question

cate grame de oxigen sunt necesare pentru a obtine 240g de oxid de magneziu?

Answer 1

[tex]m_{MgO}=240 \ g \\ \boxed{m_{O_{2}}-?} \\ \bold{Rezolvare:} \\ O_2+2Mg=2MgO \\ \boxed{\nu=\frac{m}{M}} \\ m_{O_{2}}=\nu_{O_{2}}\cdot M_{O_{2}} \\ M_{O_{2}}=16 \cdot 2=32 \ g/mol \\ \nu_{O_{2}}=x \\ \frac{x}{1}=\frac{y}{2}, \ unde \ y=\nu_{MgO} \\ \nu_{MgO}=\frac{m_{MgO}}{M_{MgO}} \\ M_{MgO}=12 \cdot 1+16 \cdot 1=12+16=28 \ g/mol \\ \nu_{MgO}=\frac{240 g }{28 \ g/mol}=8,6 \ moli \\ \Righttarrow y=8,6; \ \ \ \Rightarrow x=\frac{8,6 \cdot 1}{2}=4,3;\\ \Rightarrow \nu_{O_{2}}=4,3 \ moli [/tex]
$m_{O_{2}}=4,3 \ moli\cdot 32\ g/mol \\ \Rightarrow \boxed{\bold{m_{O_{2}}=137,6\ g}}$