`#AkaShi`
PTHH:
`Mg+2HCl -> MgCl_2 + H_2↑\ (1)`
`MgO+2HCl->MgCl_2+H_2O\ (2)`
`->n_{H_2}=(V_{H_2})/(22,4)=(2,24)/(22,4)=0,1\ (mol)`
Theo tỉ lệ pt `(1)` :
`->n_{Mg}=n_{H_2}=0,1\ (mol)`
`->m_{Mg}=n_{Mg}xxM_{Mg}=0,1xx24=2,4\ (g)`
`->m_{MgO}=m_{hh}-m_{mg}=8,8-2,4=6,4\ (g)`
`->%m_{Mg}=(2,4)/(8,8)xx100%=27,27%`
`->%m_{MgO}=(6,4)/(8,8)xx100%=72,73%`
`\text{__________________________}`
`b)`
`->n_{MgO}=(6,40)/4=0,16\ (mol)`
Theo tỉ lệ pt `(1)`:
`->n_{HCl(1)}=2xxn_{Mg}=2xx0,1=0,2\ (mol)`
Theo tỉ lệ pt `(2)`:
`->n_{HCl(1)}=2xxn_{MgO}=2xx0,16=0,32\ (mol)`
`->∑n_{HCl}=0,32+0,2=0,52\ (mol)`
`->m_{HCl}=M_{HCl}xxn_{HCl}=0,52xx36,5=18,98\ (g)`
`\text{_____________________________________}`
`c)`
`->m_{dd\ HCl}=18,98:14,6%=130\ (g)`
`->m_{dd\ sau\ pư}=130+8,8-0,1xx2=138,6\ (g)`
`->n_{MgCl_2(1)}=n_{Mg}=0,1\ (mol)`
`->n_{MgCl_2(2)}=n_{MgO}=0,16\ (mol)`
`->∑n_{MgCl_2}=0,1+0,16=0,26\ (mol)`
`->C%_{MgCl_2}=(0,26xx95)/(138,6)xx100%=17,82%`
