\(nC_2H_5OH=\dfrac{2,9}{46}=0,06\left(mol\right)\)

\(C_2H_5OH+Na\rightarrow C_2H_5ONa+\dfrac{1}{2}H_2\)

 0,06           0,06        0,06           0,03  (mol)

VH2 = 0,03.22,4= 0,672 (l)

V = m /D

=> V rượu etylic = 2,9 / 0,8 = 3,625 (ml)

Mình cần gấp mọi người ơi!!!

n_H2 = 85,12 : 22,4 = 3,8 (mol) ; n_H2O = V_H2O.D = 108 (g) => n_H2O = 108/18 = 6 (mol)

PTHH:

2Na + 2C₂H₅OH → 2C₂H₅ONa + H₂↑

                x          → 0,5x    (mol)

2Na + 2H₂O → 2NaOH + H₂↑

           6       → 3       (mol)

Ta có: n_H2 = 0,5x + 3 = 3,8

=> x = 1,6 (mol) = n_C2H5OH

m_C2H5OH = 1,6.46 = 73,6 (g)

a) 

\(V_{C_2H_5OH}=\dfrac{96.20}{100}=19,2\left(ml\right)\)

=> \(m_{C_2H_5OH}=19,2.0,8=15,36\left(g\right)\)

b) \(n_{C_2H_5OH}=\dfrac{15,36}{46}=\dfrac{192}{575}\left(mol\right)\)

\(V_{H_2O}=20-19,2=0,8\left(ml\right)\)

=> \(m_{H_2O}=0,8.1=0,8\left(g\right)\)

=> \(n_{H_2O}=\dfrac{0,8}{18}=\dfrac{2}{45}\left(mol\right)\)

PTHH: 2C₂H₅OH + 2Na --> 2C₂H₅ONa + H₂

               \(\dfrac{192}{575}\)------------------------->\(\dfrac{96}{575}\)

             2H₂O + 2Na --> 2NaOH + H₂

              \(\dfrac{2}{45}\)----------------------->\(\dfrac{1}{45}\)

=> \(V_{H_2}=22,4.\left(\dfrac{96}{575}+\dfrac{1}{45}\right)=4,238\left(l\right)\)

C2H5OH + Na -- > C2H5OHNa + 1/2 H2

Na+H2O --- > NaOH + 1/2H2

Vr = 20x96/100 = 19,2ml = 0.0192 (l)

mC2H5OH = D.V = 19,2 x 0.8 = 15.36 (g)

nC2H5OH = m/M = 15.36 / 46 = 0.43 (mol) 

=> nH2 = 0.215 (mol)

VH2O = 1 ml => mH2O = 1 (g)

=> nH2O = m/M = 1/18 = 0.056 (mol)

=> nH2 = 0.028 (mol)

nH2 = 0.215 + 0.028 = 0.243 (mol)

=> VH2 = 22.4 x 0,243  = 5,4432 (l)

\(V_{C_2H_5OH\left(\text{nguyên chất}\right)}=16.71,875\%=11,5\left(ml\right)\\ \rightarrow m_{C_2H_5OH\left(\text{nguyên chất}\right)}=11,5.0,8=9,2\left(g\right)\\ \rightarrow n_{C_2H_5OH\left(\text{nguyên chất}\right)}=\dfrac{9,2}{46}=0,2\left(mol\right)\)

PTHH: 2C₂H₅OH + 2K ---> 2C₂H₅OK + H₂

                0,2                                           0,1

=> V_H2 = 0,1.22,4 = 2,24 (l)

Đáp án B

Đáp án: A

Vì dung dịch rượu gồm rượu etylic và nước nên ta gọi:

n H 2 O = x m o l  và n C 2 H 5 O H = y m o l

PTHH:

2 N a   +   2 H 2 O   →   2 N a O H   +   H 2 ↑     ( 1 )

            x mol         →         0,5.x mol

2 N a   +   2 C 2 H 5 O H   →   2 C 2 H 5 O N a   +   H 2 ↑

              y mol         →                  0,5.y mol

Ta có hệ phương trình:

18 x + 46 y = 10 , 1 0 , 5 x + 0 , 5 y = 0 , 125 ⇒ x = 0 , 05 y = 0 , 2

V C 2 H 5 O H  nguyên chất = m D = 0 , 2 . 46 0 , 8 = 11 , 5 m l

V H 2 O = m D = 10 , 1 - 9 , 2 1 = 0 , 9 m l

=> V d d   r ư ợ u = V H 2 O + V C 2 H 5 O H = 0,9 + 11,5 = 12,4 ml

=> Độ rượu  D 0 = V C 2 H 5 O H V d d r u o u . 100 = 11 , 5 12 , 4 . 100 = 92 , 74 0

Gọi \(\left\{{}\begin{matrix}n_{C_2H_5OH}=a\left(mol\right)\\n_{H_2O}=b\left(mol\right)\end{matrix}\right.\)

\(n_{H_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\)

PTHH:

2C₂H₅OH + 2Na ---> 2C₂H₅ONa + H₂

a --------------------------------------------> 0,5a

2H₂O + 2Na ---> 2NaOH + H₂

b --------------------------------> 0,5b

Hệ pt \(\left\{{}\begin{matrix}46a+18b=20,2\\0,5a+0,5b=0,25\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,4\left(mol\right)\\b=0,1\left(mol\right)\end{matrix}\right.\)

\(\rightarrow\left\{{}\begin{matrix}m_{C_2H_5OH}=0,4.46=18,4\left(g\right)\\m_{H_2O}=0,1.18=1,8\left(g\right)\end{matrix}\right.\rightarrow\left\{{}\begin{matrix}V_{C_2H_5OH}=\dfrac{18,4}{0,8}=23\left(ml\right)\\V_{H_2O}=\dfrac{1,8}{1}=1,8\left(ml\right)\end{matrix}\right.\)

=> Độ rượu là: \(\dfrac{23}{23+1,8}=92,74^o\)