a) PTHH: \(Na_2O+H_2O\rightarrow2NaOH\)

Ta có: \(n_{NaOH}=2n_{Na_2O}=2\cdot\dfrac{6,2}{62}=0,2\left(mol\right)\) \(\Rightarrow C_{M_{NaOH}}=\dfrac{0,2}{0,4}=0,5\left(M\right)\)

b) PTHH: \(2NaOH+CuSO_4\rightarrow Cu\left(OH\right)_2\downarrow+Na_2SO_4\)

Ta có: \(\left\{{}\begin{matrix}n_{NaOH}=0,2\left(mol\right)\\n_{CuSO_4}=0,2\cdot2,5=0,5\left(mol\right)\end{matrix}\right.\)

Xét tỉ lệ: \(\dfrac{0,2}{2}< \dfrac{0,5}{1}\) \(\Rightarrow\) CuSO₄ còn dư

\(\Rightarrow\left\{{}\begin{matrix}n_{Cu\left(OH\right)_2}=0,1\left(mol\right)=n_{Na_2SO_4}\\n_{CuSO_4\left(dư\right)}=0,4\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{Cu\left(OH\right)_2}=0,1\cdot98=9,8\left(g\right)\\C_{M_{Na_2SO_4}}=\dfrac{0,1}{0,4+0,2}\approx0,17\left(M\right)\\C_{M_{CuSO_4\left(dư\right)}}=\dfrac{0,4}{0,6}\approx0,67\left(M\right)\end{matrix}\right.\)

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:

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

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

a) Đổi 300 ml = 0,3 l

Cm=\(\dfrac{n}{v}\) \(\Rightarrow\) n_NaOH= Cm.V = 0,3.1 = 0,3 Mol

PTHH: 2NaOH + FeCl₂ \(\rightarrow\) 2NaCl + Fe(OH)₂

\(\Rightarrow\) n_Fe = 0,3 Mol

\(\Rightarrow\) V_Fe = \(\dfrac{n}{Cm}\) = \(\dfrac{0,3}{0,1}\) = 3 lít

b) ta có n_{\(_{Fe\left(OH\right)_2}\)}= 0,3 Mol

\(\Rightarrow\) m_{\(_{Fe\left(OH\right)_2}\)}= n.M = 0,3.90 = 27 g

c) mk nghĩ phải cho V_NaCl mới giải đc

V = 300 ml = 0,3 (l)

=>n_NaOH = 0,3.1 = 0,3 mol

2NaOH + FeCl₂ ->2 NaCl + Fe(OH)₂

0,3------>0,15---->0,3--------0,15

a) V_FeCl2 = \(\dfrac{0,15}{0,1}\)= 1,5 (l)

b) m_Fe(OH)2 = 0,15 . 90 = 13,5 g

c) Vdd = 1,5+ 0,3 = 1,8 (l)

C_M(NaCl) = \(\dfrac{0,3}{1,8}\) = 0,1666 M

\(a.PTHH:Fe_2O_3+6HCl--->2FeCl_3+3H_2O\)

b. Ta có: \(n_{Fe_2O_3}=\dfrac{16}{160}=0,1\left(mol\right)\)

Theo PT: \(n_{HCl}=6.n_{Fe_2O_3}=6.0,1=0,6\left(mol\right)\)

\(\Rightarrow m_{HCl}=0,6.36,5=21,9\left(g\right)\)

c. Theo PT: \(n_{FeCl_3}=2.n_{Fe_2O_3}=0,1.2=0,2\left(mol\right)\)

\(\Rightarrow m_{FeCl_3}=0,2.162,5=32,5\left(g\right)\)

Ta có: \(m_{dd_{FeCl_3}}=16+284=300\left(g\right)\)

\(\Rightarrow C_{\%_{FeCl_3}}=\dfrac{32,5}{300}.100\%=10,83\%\)

n_Fe2O3= 0.1(mol)

PTHH:  Fe2O3 + 6HCl -> 2FeCl3 + 3H2O (1)

a) Theo PT (1) : n_HCl = 6 n_Fe2O3 -> n_HCl = 0.1*6= 0.6(mol)

=> m_HCl= 0.6*36.5 = 21.9(g)

b)n_FeCl3=0.2(mol)

m_FeCl3= 162.5*0.2=32.5(g)

=> m_dd sau phản ứng: 248+16 = 264(g)

=> C%_muối= 32.5:264*100=12.3%

\(m_{Fe_2\left(SO_4\right)_3}=\dfrac{200\cdot20}{100}=40\left(g\right)\Rightarrow n=0,1mol\)

\(Fe_2\left(SO_4\right)_3+6NaOH\rightarrow2Fe\left(OH\right)_3\downarrow+3Na_2SO_4\)

0,1                    0,6              0,2                   0,3

a)\(m_{NaOH}=0,6\cdot40=24\left(g\right)\)

b)\(m_{Fe\left(OH\right)_3}=0,2\cdot107=21,4\left(g\right)\)

c)\(m_{Na_2SO_4}=0,3\cdot142=42,6\left(g\right)\)

   \(m_{ddsau}=200+24-21,4=202,6\left(g\right)\)

   \(\Rightarrow C\%=\dfrac{42,6}{202,6}\cdot100\%=21,03\%\)

a) Zn + 2HCl → ZnCl2 + H2

b) Theo PTHH :

n H2 = n Zn = 13/65 = 0,2 (mol)

=> V H2 = 0,2.22,4 = 4,48(lít)

c) n ZnCl2 = n Zn = 0,2(mol)

=> m ZnCl2 = 0,2.136 = 27,2(gam)

d) CM ZnCl2 = 0,2/0,2 = 1M

Đáp án C

,n_FeCl2 = 0,1 ; n_AgNO3 = 0,5 mol

Fe²⁺ + Ag⁺  -> Fe³⁺ + Ag

Ag⁺ + Cl^- -> AgCl

=> kết tủa gồm 0,2 mol AgCl và 0,1 mol Ag

=> m_{kết tủa} = 39,5g

=>C