Bài 42: Nồng độ dung dịch

\(n_{KMnO_4\left(lt\right)}=\dfrac{31.6}{158}\cdot80\%=0.16\left(mol\right)\)

\(2KMnO_4\underrightarrow{^{^{t^0}}}K_2MnO_4+MnO_2+O_2\)

\(0.16.............................................0.08\)

\(V_{O_2}=0.08\cdot22.4=1.792\left(l\right)\)

n KMnO4 = 31,6/158 =0,2(mol)

$2KMnO_4 \xrightarrow{t^o} K_2MnO_4 + MnO_2 + O_2$

n O2(lt) = 1/2 n KMnO4 = 0,1(mol)

n O2(tt) = 0,1.80% = 0,08(mol)

V O2 = 0,08.22,4 = 1,792 lít

\(n_{Cu}=\dfrac{6.4}{64}=0.1\left(mol\right)\)

\(2Cu+O_2\underrightarrow{^{t^0}}2CuO\)

\(0.1....................0.1\)

\(m_{CuO\left(tt\right)}=0.1\cdot80=8\left(g\right)\)

\(H\%=\dfrac{m_{lt}}{m_{tt}}\cdot100\%=\dfrac{6.4}{8}\cdot100\%=80\%\)

\(n_{NaCl\left(lt\right)}=\dfrac{8.775}{58.5}=0.15\left(mol\right)\)

\(2Na+Cl_2\underrightarrow{^{t^0}}2NaCl\)

\(0.15..................0.15\)

\(m_{Na\left(tt\right)}=\dfrac{0.15\cdot23}{75\%}=4.6\left(g\right)\)

n_NaCl=\(\dfrac{8,775}{58,5}=0,15\left(mol\right)\)

PTHH 2Na+Cl₂---->2NaCl

---------0,15------------0,15

=>n_Na(tt)=\(\dfrac{0,15}{75}.100=0,2\left(mol\right)\)

=>m_Na(tt)=0,2.23=4,6(g)

\(n_{O_2}=\dfrac{43.2}{32}=1.35\left(mol\right)\)

\(2KClO_3\underrightarrow{^{t^0}}2KCl+3O_2\)

\(0.9...........................1.35\)

\(H\%=\dfrac{0.9}{1}\cdot100\%=90\%\)

PT: \(2KClO_3\underrightarrow{t^o}2KCl+3O_2\)

______1_____________1,5 (mol)

⇒ m_{O2 (lí thuyết)} = 1,5.32 = 48 (g)

Mà: m_{O2 (thực tế)} = 43,2 (g)

\(\Rightarrow H\%=\dfrac{43,2}{48}.100\%=90\%\)

Bạn tham khảo nhé!

\(n_{O_2}\)=\(\dfrac{43,2}{32}=1,35\left(mol\right)\)

PTHH 2KClO₃-----t^o--->2KCl +3O₂

=>\(n_{O_2\left(lt\right)}=1.\dfrac{3}{2}=1,5\left(mol\right)\)

=>H%=\(\dfrac{1,35}{1,5}.100\%=90\%\)

\(n_{CaO}=\dfrac{1.68\cdot1000}{56}=30\left(kmol\right)\)

\(CaCO_3\underrightarrow{^{t^0}}CaO+CO_2\)

\(30...........30\)

\(m_{CaCO_3}=30\cdot100=3000\left(kg\right)=3\left(tấn\right)\)

\(H\%=\dfrac{3}{4}\cdot100\%=75\%\)

\(n_{Al_2S_3}=\dfrac{25.5}{150}=0.17\left(mol\right)\)

\(n_{Al}=\dfrac{10.8}{27}=0.4\left(mol\right)\)

\(2Al+3S\underrightarrow{^{t^0}}Al_2S_3\)

\(0.34...........0.17\)

\(H\%=\dfrac{0.34}{0.4}\cdot100\%=85\%\)

n Al2S3 = 25,5/150=0,17(mol)

$2Al + 3S \xrightarrow{t^o} Al_2S_3$

n Al = 2n Al2S3 = 0,34(mol)
H = 0,34.27/10,8   .100% = 85%

n_NaCl = C_M .V = 2,5.0,9 = 2,25 (mol)

→ m_NaCl = 2,25.(23 + 35,5) = 131,625 (g)

nNaCl = CM.V = 2,5.0,9 = 2,25 (mol)

=> mNaCl = 2,25.(23 + 35,5) = 131,625 (g).

a) CM MgCl2 = 0,5/1,5 = 0,33M

b) n CuSO4 = 400/160 = 2,5(mol)

CM CuSO4 = 2,5/4 = 0,625M

a) `CM_(MgCl_2) = (0,5)/(1,5)`\(\approx\)`0,33 M`

b) `n_(CuSO_4)=2,5(mol)`

→ `CM_(CuSO_4)=(2,5)/4=0,625 M`

`C% = m_(ct)/m_(dd) . 100`

⇔ `m_(ct)= C%.m_(dd)/100 = (4.50)/100=2(g)`

\(a.\)

\(C\%_{KCl}=\dfrac{20}{600}\cdot100\%=3.33\%\)

\(b.\)

\(C\%_{NaNO_3}=\dfrac{32}{2000}\cdot100\%=1.6\%\)