Coi 

\(m_{dd\ NaOH} = 100\ gam\\ \Rightarrow n_{NaOH} = \dfrac{100.10\%}{40} = 0,25(mol)\)

CH₃COOH + NaOH → CH₃COONa + H₂O

0,25................0,25.................0,25......................(mol)

\(m_{CH_3COONa} = 0,25.82 = 20,5(gam)\\ \Rightarrow m_{dd\ sau\ pư} = \dfrac{20,5}{10,25\%} = 200(gam)\\ \Rightarrow m_{dd\ axit\ axetic} = 200 -100 = 100(gam)\)

Vậy :

\(C\%_{CH_3COOH} = \dfrac{0,25.60}{100}.100\% = 15\%\)

Số mol NaOH là :

\(\dfrac{100.10}{100.40} = 0,25\) (mol)

PTHH : \(CH_3COOH +NaOH \) \(\rightarrow\) \(CH_3COONa +H_2O\)

Pư : 0,25 \(\leftarrow\) 0,25 \(\rightarrow\) 0,25 (mol)

Khối lượng \(CH _3\)COOH = 0,25.60=15(g)

\(\Rightarrow\) Khối lượng dd \(CH_3\)COOH a% là : 15. \(\dfrac{100}{a}\) % = \(\dfrac{1500}{a}\) (g)

Khối lượng muối \(CH_3COONa : 0,25.82=20,5\) (g)

Trong dd muối thu được sau phản ứng :

\(m_{tan}\) = \(m_{ {CH_3COONa}}= 20,5 \) (g)

\(m_{dd} = m_{ddCH_3COOH} +m_{ddNaOH} = \dfrac{1500}{a} +100\) (g)

Đặt : \(\dfrac{1500}{a} +100 = \) m

C% của muối là : 10,25%

Ta có : 10,25% = \(\dfrac{20,5.100%}{m}\) % \(\Rightarrow\) m = 200

Từ \(\dfrac{1500}{a} +100 = \) m = 200 \(\Rightarrow\) a = 15%

CH3COOH + NaOH -> CH3COONa + H2O

1........................1..................1 (mol)

Gia su số mol NaOH là 1 mol

=> m_{dung dịch NaOH} = 40/10% = 400(g)

=> m _{dung dịch sau} = \(\frac{60}{a\%}+400\left(g\right)\)

Theo bài ra : \(C\%_{CH3COONa}=\frac{82}{\frac{60}{a\%}+400}.100\%=10,25\%\)

=> a = 15 %

Tham khảo:

Gọi x là số mol CH3COOH ban đầu .
CH3COOH + NaOH --->CH3COONa + H2O.
x mol ............x mol .........x mol
* m(CH3COOH) = 60x gam .
*m(dung dịch CH3COOH)= (60x.100)/a gam .
*m(NaOH) = 40x gam
=>m(dung dịch NaOH) = (40x.100)/10 = 400x gam
=>m(dung dịch sau phản ứng) = 400x + 6000x/a gam
*m(CH3COONa ) = 82x gam.
Ta có :
%(CH3COONa )=10,25 = 82x.100/(400x + 6000x/a)
=>a = 15%

ĐÁP ÁN D:

Đặt n_CH3COOH = x mol và n_HCOOH= y mol giả sử phản ứng vừa hết 100g dd NaOH => n_NaOH = n_H+ = x + y = 0,25 mol

=> n_CH3COONa= x mol => %m_CH3COONa =

=> x= 0,1 mol ; y= 0,15 mol => m _{dd sau}= 112,9g =.%m_HCOONa = 9,035%

=> chọn D

$a\big)$

$n_{CH_3COOH}=\dfrac{100}{1000}.1=0,1(mol)$

$CH_3COOH+NaOH\to CH_3COONa+H_2O$

Theo PT: $n_{NaOH}=n_{CH_3COOH}=0,1(mol)$

$\to C\%_{NaOH}=\dfrac{0,1.40}{50}.100\%=80\%$

$b\big)$

$n_{Na_2CO_3}=\dfrac{10,6}{106}=0,1(mol)$

$2CH_3COOH+Na_2CO_3\to 2CH_3COONa+CO_2+H_2O$

Theo PT: $\begin{cases} n_{CO_2}=n_{Na_2CO_3}=0,1(mol)\\ n_{CH_3COONa}=2n_{Na_2CO_3}=0,2(mol) \end{cases}$

$\to C\%_{CH_3COONa}=\dfrac{0,2.82}{60+10,6-0,1.44}.100\%\approx 24,77\%$

Đáp án B

Đáp án : B

\(a,n_{CuO}=\dfrac{4}{80}=0,05\left(mol\right)\)

PTHH: \(CuO+2HCl\rightarrow CuCl_2+H_2O\)

           0,05---->0,1------>0,1

\(\rightarrow x=C\%_{HCl}=\dfrac{0,1.36,5}{200}.100\%=1,825\%\)

\(b,\) PTHH: \(CuCl_2+2NaOH\rightarrow Cu\left(OH\right)_2\downarrow+2NaCl\)

                 0,05----->0,1-------->0,05----------->0,1

\(\rightarrow m_{ddNaOH}=\dfrac{0,1.40}{10\%}=40\left(g\right)\\ \rightarrow m_{dd\left(sau.pư\right)}=40+200+4-0,05.98=239,1\left(g\right)\)

\(\rightarrow C\%_{NaCl}=\dfrac{0,1.58,5}{239,1}.100\%=2,45\%\)

\(n_{CuO}=\dfrac{4}{80}=0,05\left(mol\right)\\ pthh:CuO+HCl\rightarrow CuCl_2+H_2O\)
          0,05     0,05      0,05        0,05 
\(x=C\%_{HCl}=\dfrac{0,05.36,5}{200}.100\%=0,9125\%\\ pthh:CuCl_2+2NaOH\rightarrow Cu\left(OH\right)_2+2NaCl\) 
      
 

\(m_{CH_3COOH}=100.6\%=6\left(g\right)\Rightarrow n_{CH_3COOH}=\dfrac{6}{60}=0,1\left(mol\right)\)

PT: \(CH_3COOH+NaHCO_3\rightarrow CH_3COONa+CO_2+H_2O\)

Theo PT: \(n_{NaHCO_3}=n_{CH_3COOH}=0,1\left(mol\right)\)

\(\Rightarrow a=C_{M_{NaHCO_3}}=\dfrac{0,1}{0,05}=2\left(M\right)\)

a) Na₂CO₃ + 2CH₃COOH --> 2CH₃COONa + CO₂ + H₂O

b) \(n_{CH_3COOH}=\dfrac{25.6\%}{60}=0,025\left(mol\right)\)

PTHH: Na₂CO₃ + 2CH₃COOH --> 2CH₃COONa + CO₂ + H₂O

              0,0125<-----0,025------------>0,025------>0,0125

=> \(m_{Na_2CO_3}=0,0125.106=1,325\left(g\right)\)

c) \(m_{dd.sau.pư}=1,325+25-0,0125.44=25,775\left(g\right)\)

\(C\%_{dd.CH_3COONa}=\dfrac{0,025.82}{25,775}.100\%=7,95\%\)

m CH3COOH=1,5g=>n=0,025 mol

2CH3COOH+Na2CO3->2CH3COONa+H2O+CO2

0,025--------------0,0125----------0,025

=>m Na2CO3=0,0125.106=1,325g

=>mdd=25g

c) 

C% =\(\dfrac{0,025.82}{25+25}100=4,1\%\)