Tiếp bài của creeper nhé:

c. Ta có: \(n_{ZnO}=\dfrac{4,86}{81}=0,06\left(mol\right)\)

Theo PT₍₁₎: \(n_{HCl}=2.n_{ZnO}=2.0,06=0,12\left(mol\right)\)

Theo PT₍₂₎: \(n_{HCl}=2.n_{Zn}=2.0,1=0,2\left(mol\right)\)

=> \(n_{HCl}=0,12+0,2=0,32\left(mol\right)\)

=> \(m_{HCl}=0,32.36,5=11,68\left(g\right)\)

Ta có: \(C_{\%_{HCl}}=\dfrac{11,68}{m_{dd_{HCl}}}.100\%=12\%\)

=> \(m_{dd_{HCl}}=\dfrac{292}{3}\left(g\right)\)

Theo đề, ta có: 

\(D=\dfrac{\dfrac{292}{3}}{V_{dd_{HCl}}}=1,2\)(g/ml)

=> \(V_{dd_{HCl}}=81,1\left(ml\right)\)

Đặt: \(n_{Zn}=a\left(mol\right);n_{ZnO}=b\left(mol\right)\left(a,b>0\right)\)

\(n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)

\(a.Zn+2HCl\rightarrow ZnCl_2+H_2\\ ZnO+2HCl\rightarrow ZnCl_2+H_2O\\ \Rightarrow\left\{{}\begin{matrix}65a+81b=14,6\\a=0,1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,1\\b=0,1\end{matrix}\right.\\ b.m_{Zn}=0,1.65=6,5\left(g\right)\\ m_{ZnO}=0,1.81=8,1\left(g\right)\\ d.m_{ddHCl}=\dfrac{\left(0,1+0,1\right).2.36,5.100}{7,3}=200\left(g\right)\)

Bạn ơi cho mình hỏi là khúc cuối ấy Nhân 2 ở đâu ra vậy???? 

C32: 

a, \(n_C=\dfrac{2,4}{12}=0,2\left(mol\right)\)

PT: \(C+O_2\underrightarrow{t^o}CO_2\)

Theo PT: \(n_{CO_2}=n_C=0,2\left(mol\right)\Rightarrow V_{CO_2}=0,2.22,4=4,48\left(l\right)\)

b, \(n_{NaOH}=0,3.1=0,3\left(mol\right)\)

\(\Rightarrow\dfrac{n_{NaOH}}{n_{CO_2}}=1,5\) → Pư tạo NaHCO₃ và Na₂CO₃

PT: \(CO_2+NaOH\rightarrow NaHCO_3\)

\(CO_2+2NaOH\rightarrow Na_2CO_3+H_2O\)

Ta có: \(\left\{{}\begin{matrix}n_{CO_2}=n_{NaHCO_3}+n_{Na_2CO_3}=0,2\\n_{NaOH}=n_{NaHCO_3}+2n_{Na_2CO_3}=0,3\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}n_{NaHCO_3}=0,1\left(mol\right)\\n_{Na_2CO_3}=0,1\left(mol\right)\end{matrix}\right.\)

⇒ m_NaHCO3 = 0,1.84 = 8,4 (g)

m_Na2CO3 = 0,1.106 = 10,6 (g)

c, \(C_{M_{NaHCO_3}}=C_{M_{Na_2CO_3}}=\dfrac{0,1}{0,3}=\dfrac{1}{3}\left(M\right)\)

Lần sau bạn đăng tách câu hỏi ra nhé.

C31:

a, \(Zn+2HCl\rightarrow ZnCl_2+H_2\)

\(ZnO+2HCl\rightarrow ZnCl_2+H_2O\)

b, \(n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\)

Theo PT: \(n_{Zn}=n_{H_2}=0,1\left(mol\right)\)

\(\Rightarrow\left\{{}\begin{matrix}\%m_{Zn}=\dfrac{0,1.65}{14,6}.100\%\approx44,52\%\\\%m_{ZnO}\approx55,48\%\end{matrix}\right.\)

c, \(n_{ZnO}=\dfrac{14,6-0,1.65}{81}=0,1\left(mol\right)\)

Theo PT: \(n_{HCl}=2n_{Zn}+2n_{ZnO}=0,4\left(mol\right)\)

\(\Rightarrow m_{ddHCl}=\dfrac{0,4.36,5}{10\%}=146\left(g\right)\)

2Al + 6HCl -> 2AlCl₃ + 3H₂ (1)

ZnO + 2HCl -> ZnCl₂ + H₂O (2)

a) n_H2= 13,44/22.4=0.6(mol) -> mH2=0,6.2=1,2(g)

Theo PTHH: n_Al = 2/3 n_H2 = 2/3 . 0,6= 0,4(mol) -> m_Al = 0,4 . 27=10,8(g)

-> m_ZnO = 27-10,8= 16,2(g)

b) n_ZnO = 16,2/81=0,2(mol)

Theo PTHH (2): nHCl = 2nZnO=2.0,2=0,4(mol)

Theo PTHH (1) : nHCl=2nH₂=2.0,6=1,2(mol)

-> \(\Sigma\)nHCl = 0,4+1,2=1,6(mol)

-> mHCl = 1,6.36,5= 58,4(g)

-> mdd_HCl = 58,4.100/29,2= 200(g)

c) Theo PTHH (1): nAlCl₃ = 2/3 nH₂ = 2/3 . 0,6=0,4(mol)                                         -> mAlCl3=0,4.133,5=53,4(g)

mdd sau phản ứng= m_A + mddHCl - mH2 =27+200-1,2 =225,8(g)

-> C% AlCl3 = 53,4.100%/225,8 = 20,88%

Theo PTHH (2) nZnCl2 =nZnO= 0,2(mol)-> mZnCl2=0,2.136=27,2(g)

-> C% ZnCl2= 27,2.100%/255,8=10,63%

Bạn ơi bài này mình giải phương trình được chứ?

a)

$2K + 2H_2O \to 2KOH + H_2$
$BaO + H_2O \to Ba(OH)_2$
Theo PTHH : 

$n_K = 2n_{H_2} = 0,2(mol)$
$\%m_K = \dfrac{0,2.39}{23,1}.100\% = 33,77\%$

$\%m_{BaO} = 100\%- 33,77\% = 66,23\%$

b)

$n_{BaO} = \dfrac{23,1 - 0,2.39}{153} = 0,1(mol)$

$m_{dd} = 23,1 + 177,1 - 0,1.2 = 200(gam)$
$C\%_{KOH} = \dfrac{0,2.56}{200}.100\% = 5,6\%$

$C\%_{Ba(OH)_2} = \dfrac{0,1.171}{200}.100\% = 8,55\%$

c)

$KOH + HCl \to KCl + H_2O$
$Ba(OH)_2 + 2HCl \to BaCl_2 + 2H_2O$
$n_{HCl} = 2n_{Ba(OH)_2} + n_{KOH} = 0,4(mol)$
$V = \dfrac{0,4}{0,5} = 0,8(lít) = 800(ml)$

n_H2 = \(\dfrac{3,36}{22,4}=0,15\left(mol\right)\)

Fe + 2HCl ---> FeCl₂ + H₂

0,15    0,3           0,15     0,15

m_Fe = 0,15.56 = 8,4 (g)

m_Fe2O3 = 24,4 - 8,4 = 16 (g)

n_Fe2O3 = \(\dfrac{16}{160}=0,1\left(mol\right)\)

%m_Fe = \(\dfrac{8,4}{24,4}=34,42\%\)

%m_Fe2O3 = \(100\%-34,42\%=65,58\%\)

Fe₂O₃ + 6HCl ---> 2FeCl₃ + 3H₂O

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

n_{HCl (ban đầu)} = 0,8.1,5 = 1,2 (mol)

n_{HCl (dư)} = 1,2 - 0,3 - 0,6 = 0,3 (mol)

=> \(\left\{{}\begin{matrix}C_{MFeCl_3}=\dfrac{0,2+0,15}{0,8}=0,4375M\\C_{MHCl\left(dư\right)}=\dfrac{0,3}{0,8}=0,375M\end{matrix}\right.\)

PTHH: 

FeCl₃ + 3NaOH ---> Fe(OH)₃ + 3NaCl

0,35        1,05

HCl + NaOH ---> NaCl + H₂O

0,3       0,3

=> \(V_{ddNaOH}=\dfrac{1,05+0,3}{1}=1,35\left(l\right)=1350\left(ml\right)\)