`Zn+2HCl->ZnCl_2+H_2`
`ZnO+2HCl->ZnCl_2+H_2O`
`a)``n_{H_2}=(7,84)/(22,4)=0,35(mol)`
`n_{Zn}=n_{H_2}=0,35(mol)`
`%m_{Zn}=(0,35.65)/(25,95%)=87,67%`
`%m_{ZnO}=100%-87,67%=12,33%`
`b)``n_{ZnO}=(25,95-(0,35.65))/(65+16)≈0,04(mol)`
`n_{HCl}=(0,35.2)+(0,04.2)=0,78(mol)`
`%m_{HCl}=(0,78.3,5)/(250%)=11,388%`
`m_{dd(spu)}=25,95+250-0,35.2=275,25(g)`
`m_{muoi}=0,35.(65+35,5.2)+0,04.(65+35,5.2)=53,04(g)`
`%m_{muoi}=(53,04)/(275,25%)=19,27%`
