Câu 4:
\(2Al+3S\rightarrow Al_2S_3\)
\(n_S=0,3\left(mol\right)\)
\(n_{Al}=0,25\left(mol\right)\)
\(\frac{n_{Al}}{2}>\frac{n_S}{3}\Rightarrow\) Al dư, Al2S3
\(m_{Al\left(dư\right)}=0,25-\frac{2}{3}.0,3=0,05\left(mol\right)\)
\(\Rightarrow m=1,35\left(g\right)\)
\(\Rightarrow m_{Al2S3}=\frac{1}{3}.0,3.150=15\left(g\right)\)
Câu 5:
\(2Na+S\rightarrow Na_2S\)
\(n_S=0,1\left(mol\right)\)
\(n_{Na}=0,1\left(mol\right)\)
\(\frac{n_{Na}}{2}< \frac{n_S}{1}\)
\(m_{S\left(dư\right)}=0,1-\frac{1}{2}.0,1=0,05\left(mol\right)\)
\(\Rightarrow m=1,6\left(g\right)\)
\(\Rightarrow m_{Na2S}=0,1.\frac{1}{2}.78=3,9\left(g\right)\)
Câu 6:
\(S+Fe\rightarrow FeS\)
\(n_S=0,2\left(mol\right)\)
\(n_{Fe}=0,1\left(mol\right)\)
S dư
\(m_{S\left(Dư\right)}=0,1.32=3,2\left(g\right)\)
\(m_{FeS}=0,1.88=8,8\left(g\right)\)
Câu 7:
Gọi a và b là số mol của S trong 2 phương trình
\(S+Fe\rightarrow FeS\)
\(3S+2Al\rightarrow Al_2S_3\)
Giải hệ PT:
\(\left\{{}\begin{matrix}a+b=0,04\\56a+18b=1,1\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}a=0,01\\b=0,03\end{matrix}\right.\)
\(\%m_{Fe}=\frac{0,01.56}{1,1}.100\%=50,9\%\)
\(\%m_{Al}=100\%-50,9\%=49,1\%\)
