Sửa đề 2,6 -> 2,3 gam

a) $2Na + 2H_2O \to 2NaOH + H_2$

n Na = 2,3/23 = 0,1(mol)

n H2 = 1/2 n Na = 0,05(mol)

=> V H2 = 0,05.22,4 = 1,12(lít)

b) n NaOH = n Na = 2,3/23 = 0,1(mol)

=> CM NaOH = 0,1/0,2 = 0,5M

\(Fe+H_2SO_4 \to FeSO_4+H_2\\ n_{H_2}=0,15(mol)\\ a/\\ n_{Fe}=n_{H_2}=0,15(mol)\\ m_{Fe}=0,15.56=8,4(g)\\ b/\\ n_{H_2SO_4}=n_{H_2}=0,15(mol)\\ CM_{H_2SO_4}=\dfrac{0,15}{2}=0,75M c/\\ n_{FeSO_4}=n_{H_2}=0,15(mol)\\ CM_{FeSO_4}=\dfrac{0,15}{0,2}=0,75M\\\)

\(Mg+H_2SO_4\rightarrow MgSO_4+H_2\uparrow\\ n_{Mg}=n_{H_2SO_4}=n_{H_2}=\dfrac{3,36}{22,4}=0,15\left(mol\right)\\ a,m_{Mg}=0,15.24=3,6\left(g\right)\\ b,C_{MddH_2SO_4}=\dfrac{0,15}{0,2}=0,75\left(M\right)\)

Bài 1 : 

a) $2Na + 2H_2O \to 2NaOH + H_2$

b) $n_{H_2} = \dfrac{5,6}{22,4} = 0,25(mol) \Rightarrow n_{Na} = 2n_{H_2} = 0,5(mol)$
$m_{Na} = 0,5.23 = 11,5(gam)$

c) $n_{NaOH} = n_{Na} = 0,5(mol)$

$C_{M_{NaOH}} = \dfrac{0,5}{0,2} = 2,5M$

$m_{H_2O} = D.V = 200.1 = 200(gam)$

$m_{dd} = 11,5 + 200 - 0,25.2 = 211(gam)$
$C\%_{NaOH} = \dfrac{0,5.40}{211}.100\% = 9,48\%$

Bài 2:

\(n_{Al}=\dfrac{2,7}{27}=0,1\left(mol\right)\\ n_{O_2}=\dfrac{11,2.20\%}{22,4}=0,1\left(mol\right)\\ 4Al+3O_2\underrightarrow{^{to}}2Al_2O_3\\ Vì:\dfrac{0,1}{4}< \dfrac{0,3}{1}\Rightarrow O_2dư\\ \Rightarrow Sau.p.ứng:Al_2O_3,O_2dư,N_2\\ n_{N_2}=\dfrac{80}{20}.0,1=0,4\left(mol\right)\Rightarrow m_{N_2}=28.0,4=11,2\left(g\right)\\ n_{O_2\left(dư\right)}=0,1-\dfrac{3}{4}.0,1=0,025\left(mol\right)\\ m_{O_2\left(dư\right)}=0,025.32=0,8\left(g\right)\\ n_{Al_2O_3}=\dfrac{2}{4}.0,1=0,05\left(mol\right)\\ m_{Al_2O_3}=102.0,05=5,1\left(g\right)\)

Bài 2 : 

$n_{Al} = \dfrac{2,7}{27} = 0,1(mol) ; n_{O_2} = \dfrac{11,2.20\%}{22,4} = 0,1(mol)$
$4Al + 3O_2 \xrightarrow{t^o} 2Al_2O_3$

Ta thấy : 

$n_{Al} : 4 < n_{O_2} : 3$ nên $O_2$ dư

Sau phản ứng, thu được : 

$n_{Al_2O_3} = \dfrac{1}{2}n_{Al} = 0,05(mol) \Rightarrow m_{Al_2O_3} = 0,05.102 = 5,1(gam)$
$n_{O_2\ pư} = \dfrac{3}{4}n_{Al} = 0,075(mol) \Rightarrow m_{O_2\ dư} = (0,1 - 0,075).32 = 0,8(gam)$
$n_{N_2} = 0,5 - 0,1 = 0,4(mol) \Rightarrow m_{N_2} = 0,4.28 = 11,2(gam)$

\(n_{H_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\\ a.2Na+2H_2O\rightarrow2NaOH+H_2\\ b.0,5.......0,5.........0,5..........0,25\left(mol\right)\\ b.m_{Na}=0,5.23=11,5\left(g\right)\\ c.C\%_{ddA}=C\%_{ddNaOH}=\dfrac{0,5.40}{0,5.23+200.1-0,25.2}.100\approx9,479\%\)

\(n_{H2}=\dfrac{4,48}{22,4}=0,2\left(mol\right)\)

Pt : \(2Na+2H_2O\rightarrow2NaOH+H_2|\)

         2          2                2            1

        0,4                         0,4         0,2

a) \(n_{Na}=\dfrac{0,2.2}{1}=0,4\left(mol\right)\)

⇒ \(m_{Na}=0,4.23=9,2\left(g\right)\)

b) \(n_{NaOH}=\dfrac{0,2.2}{1}=0,4\left(mol\right)\)

⇒ \(m_{NaOH}=0,4.40=16\left(g\right)\)

\(m_{ddspu}=9,2+191,2-\left(0,2.2\right)=200\left(g\right)\)

\(C_{NaOH}=\dfrac{16.100}{200}=8\)⁰/₀

 Chúc bạn học tốt

nNa=0,2.21=0,4(mol)nNa=0,2.21=0,4(mol)

⇒ mNa=0,4.23=9,2(g)mNa=0,4.23=9,2(g)

b) CNaOH=16.100200=8CNaOH=16.100200=8⁰/₀

\(n_{Na}=\dfrac{6,9}{23}=0,3\left(mol\right)\\ 2Na+2H_2O\rightarrow2NaOH+H_2\\ n_{H_2}=\dfrac{0,3}{2}=0,15\left(mol\right)\\ a,V_{H_2\left(đktc\right)}=0,15.22,4=3,36\left(l\right)\\ b,m_{ddsaup.ứ}=m_{Na}+m_{H_2O}-m_{H_2}=6,9+100-0,15.2=106,6\left(g\right)\)