a, Ta có : \(\dfrac{n_{Al}}{n_{Mg}}=\dfrac{2}{1}\)

Mà \(m_{hh}=m_{Al}+m_{Mg}=27n_{Al}+24n_{Mg}=7,8\)

\(\Rightarrow\left\{{}\begin{matrix}n_{Al}=0,2\\n_{Mg}=0,1\end{matrix}\right.\) mol

b, Ta có : \(\left\{{}\begin{matrix}m_{Al}=n.M=5,4\\m_{Mg}=n.M=2,4\end{matrix}\right.\) g

Vậy ...

\(n_{H_2SO_4}=5a\left(mol\right),n_{HCl}=3a\left(mol\right)\)

\(m=98\cdot5a+36.5\cdot3a=5.995\left(g\right)\)

\(\Rightarrow a=0.01\)

\(n_{H_2SO_4}=0.05\left(mol\right),n_{HCl}=0.03\left(mol\right)\)

\(b.\)

\(n_{H_2SO_4}=0.025\left(mol\right),n_{HCl}=0.015\left(mol\right)\)

\(n_{CO}=x\left(mol\right),n_{CO_2}=y\left(mol\right)\)

\(n_B=x+y=0.025+0.015=0.04\left(mol\right)\left(1\right)\)

\(m_B=28x+44y=2.16\left(g\right)\left(2\right)\)

\(\left(1\right),\left(2\right):\) Không biết sao tới chổ này số mol âm mất em ơii

\(\left\{{}\begin{matrix}n_{Cl_2}+n_{O_2}=\dfrac{8,96}{22,4}=0,4\left(mol\right)\\\dfrac{n_{Cl_2}}{n_{O_2}}=\dfrac{1}{3}\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}n_{Cl_2}=0,1\left(mol\right)\\n_{O_2}=0,3\left(mol\right)\end{matrix}\right.\)

=> \(\left\{{}\begin{matrix}m_{Cl_2}=0,1.71=7,1\left(g\right)\\m_{O_2}=0,3.32=9,6\left(g\right)\end{matrix}\right.\)

=> m_hh = 7,1 + 9,6 = 16,7(g)

Đặt $n_{Cl_2}=x(mol)\Rightarrow n_{O_2}=3x(mol)$

Mà $n_{hh}=n_{Cl_2}+n_{O_2}=\dfrac{8,96}{22,4}=0,4$

$\Rightarrow x+3x=0,4\Rightarrow x=0,1$

$\Rightarrow m_{Cl_2}=0,1.71=7,1(g);m_{O_2}=3.0,1.32=9,6(g)$

$\Rightarrow m_{hh}=7,1+9,6=16,7(g)$

a)

Gọi n Fe = 3a(mol) ; n Mg = 2a(mol)

Suy ra : 

3a.56 + 2a.24 = 21,6

=> a = 0,1

Vậy : n Fe = 0,3 ; n Mg = 0,2(mol)

$3Fe + 2O_2 \xrightarrow{t^o} Fe_3O_4$

$2Mg + O_2 \xrightarrow{t^o} 2MgO$
n Fe3O4 = 1/3 n Fe = 0,1(mol) => m Fe3O4 = 0,1.232 = 23,2(gam)

n MgO = n Mg = 0,2(mol) => m MgO = 0,2.40 = 8(gam)

b)

n O2 = 2/3 n Fe + 1/2 n Mg = 0,3(mol)

V O2 = 0,3.22,4 = 6,72 lít

help me

1, a, + 8.2=16 => CH₄

+ 8,5 . 2 = 17 => NH₃

+ 16 . 2 =32 => O₂
+ 22 . 2 = 44 => CO₂

b, + 0,138 . 29 \(\approx4\) => He

+ 1,172 . 29 \(\approx34\) => H₂S

+ 2,448 . 29 \(\approx71\Rightarrow Cl_2\)

+ 0,965 . 29 \(\approx28\) => N