pt CH3COOH+NaOH\(\rightarrow\)CH3COONa+H2O

ta có mCH3COOH=15*120:100=18 g\(\Rightarrow\)nCH3COOH=0,3 mol

mNaOH=20*100:100=20g\(\Rightarrow\)nNaOH=0,5 mol

theo pt thì NaOH dư

ta có nCH3COONa=nCH3COOH=0,3 mol\(\Rightarrow\)mCH3COONa=24,6 g

ta có m dd sau phản ứng =120+100=220 g \(\Rightarrow\)C%CH3COONa=11,2%

Mg+2CH₃COOH->(CH₃COO)₂Mg+H₂

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

n _Mg=\(\dfrac{3,6}{24}\)=0,15 mol

m _CH3COOH=24g =>n _CH3COOH=\(\dfrac{24}{60}\)=0,6 mol

->CH3COOH dư

=>C% _(CH3COO)2Mg=\(\dfrac{0,15.142}{200+3,6-0,15.2}\).100=10,48%

=>C% _{CH3COOH dư}= \(\dfrac{0,3.60}{200+3,6-0,15.2}\).100=8,85%

\(C\%_{ddNaOH\left(thu.được\right)}=\dfrac{20}{20+150}.100\%\approx11,765\%\)

\(m_{CH_3COOH}=12\%.100=12\left(g\right)\\ n_{CH_3COOH}=\dfrac{12}{60}=0,2\left(mol\right)\)

PTHH: CH₃COOH + NaOH ---> CH₃COONa + H₂O

               0,2--------->0,2------------>0,2

\(m_{NaOH}=0,2.40=8\left(g\right)\\ m_{ddNaOH}=\dfrac{8}{8,4\%}=\dfrac{2000}{21}\left(g\right)\\ m_{ddCH_3COONa}=\dfrac{2000}{21}+100=\dfrac{4100}{21}\left(g\right)\\ m_{CH_3COONa}=0,2.82=16,4\left(g\right)\\ C\%_{CH_3COONa}=\dfrac{16,4}{\dfrac{4100}{21}}.100\%=8,4\%\)

`=>` Gợi ý:

`CH3COOH + NaHCO3 => CH3COONa + CO2 + H2O`

`m<sub>CH3COOH</sub> = 100x12/100 = 12` (g)

`==> n<sub>CH3COOH</sub> = m/M = 12/60 = 0.2` (mol)

Theo pt: `=> n<sub>NaHCO3</sub> = 0.2` (mol)

`==> m<sub>NaHCO3</sub> = n.M = 0.2x84 =16.8` (g)

`==> m<sub>dd NaHCO3</sub> = 16.8x100/8.4 = 200` (g)

Ta có: `n<sub>CH3COONa</sub> = 0.2` (mol)

a,Giả sử m_ddHCl = 36,5 (g) \(\Rightarrow n_{HCl}=\dfrac{36,5.0,2}{36,5}=0,2\left(mol\right)\)

PTHH: Fe + 2HCl → FeCl₂ + H₂

Mol:     a         2a          a         a

PTHH: Mg + 2HCl → MgCl₂ + H₂

Mol:       b         2b           b         b

Ta có: \(2a+2b=0,2\Leftrightarrow a+b=0,1\left(mol\right)\)

m_{dd D} = 56a+24b+36,5-(a+b).2 = 56a+24b+36,3 (g)

\(C\%_{ddFeCl_2}=\dfrac{127a.100\%}{56a+24b+36,3}=15,757\%\)

\(\Leftrightarrow127a=8,82392a+3,78168b+5,719791\)

\(\Leftrightarrow118,17608a-3,78168b=5,719791\)

Ta có: \(\left\{{}\begin{matrix}a+b=0,1\\118,17608a-3,78168b=5,719791\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=0,05\\b=0,05\end{matrix}\right.\)

\(C\%_{ddMgCl_2}=\dfrac{95.0,05.100\%}{56.0,05+24.0,05+36,3}=11,79\%\)

a, \(Mg+2HCl\rightarrow MgCl_2+H_2\)

b, \(n_{Mg}=\dfrac{1,2}{24}=0,05\left(mol\right)\)

Theo PT: \(n_{HCl}=2n_{Mg}=0,1\left(mol\right)\Rightarrow m_{ddHCl}=\dfrac{0,1.36,5}{10\%}=36,5\left(g\right)\)

c, \(n_{H_2}=n_{MgCl_2}=n_{Mg}=0,05\left(mol\right)\)

Ta có: m _{dd sau pư} = 1,2 + 36,5 - 0,05.2 = 37,6 (g)

\(\Rightarrow C\%_{MgCl_2}=\dfrac{0,05.95}{37,6}.100\%\approx12,63\%\)

 5 Nồng độ phần trăm là gì? Trong hóa học, nồng độ phần trăm của dung dịch được kí hiệu là C% cho ta biết số gam chất tan có trong 100 gam dung dịch là bao nhiêu

C%=\(\dfrac{20}{620}.100=3,22\%\)

CM=\(\dfrac{1,5}{0,75}\)=2M

6 ko giải thích lại

C%=\(\dfrac{30}{230}100=13\%\)

CM=\(\dfrac{1}{0,2}\)=5M