1.
PTHH: \(Mg+2HCl\)→\(MgCl_2+H_2\)
Theo ĐLBTKL ta có:
\(m_{MgCl_2}=m_{Mg}+m_{HCl}-m_{H_2}\)
\(m_{MgCl_2}=7,2+21,9-0,6=28,5\left(gam\right)\)
2.
PTHH: \(4P+5O_2\)→\(2P_2O_5\)
+Theo ĐLBTKL ta có:
\(m_{P_2O_5}=m_P+m_{O_2}\)
\(m_{P_2O_5}=12,4+16\)= 28,4 (gam)