Cho dung dịch Ca(OH)2 X% tác dụng vừa đủ với dung dịch CH3COOH 15% thì thu được dung dịch muối có nồng độ 9,875%. Hãy tính X
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Giả sử có 100g dd CH3COOH 15%
Ta có:
nCH3COOH=\(\dfrac{100.15\%}{60}\)=0,25(mol)
PTHH:Ca(OH)2+2CH3COOH→(CH3COO)2Ca+2H2O
⇒nCa(OH)2=n(CH3COO)2Ca=0,125(mol)
⇒mdd(Ca(OH)2)=\(\dfrac{0,125.74}{X\%}\)=9,25
⇒mdd(spu)=\(\dfrac{9,25}{X\%+100}\)⇔C%=9,875%
\(\dfrac{0,125.158.100}{\dfrac{9,25}{X\%+100}}\)=9,875⇔x=9,25
![](https://rs.olm.vn/images/avt/0.png?1311)
$a\big)$
$n_{CH_3COOH}=\dfrac{100}{1000}.1=0,1(mol)$
$CH_3COOH+NaOH\to CH_3COONa+H_2O$
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: $\begin{cases} n_{CO_2}=n_{Na_2CO_3}=0,1(mol)\\ n_{CH_3COONa}=2n_{Na_2CO_3}=0,2(mol) \end{cases}$
$\to C\%_{CH_3COONa}=\dfrac{0,2.82}{60+10,6-0,1.44}.100\%\approx 24,77\%$
![](https://rs.olm.vn/images/avt/0.png?1311)
* Ta có: \(n_{CO_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\)
a. PTHH: \(CO_2+Ca\left(OH\right)_2--->CaCO_3\downarrow+H_2O\)
b. Theo PT: \(n_{Ca\left(OH\right)_2}=n_{CO_2}=0,25\left(mol\right)\)
Đổi 100ml = 0,1 lít
=> \(C_{M_{Ca\left(OH\right)_2}}=\dfrac{0,25}{0,1}=2,5M\)
* PTHH: X2O3 + 3H2SO4 ---> X2(SO4)3 + 3H2O
Đổi 600ml = 0,6 lít
Ta có: \(n_{H_2SO_4}=1.0,6=0,6\left(mol\right)\)
Theo PT: \(n_{X_2O_3}=\dfrac{1}{3}.n_{H_2SO_4}=\dfrac{1}{3}.0,6=0,2\left(mol\right)\)
=> \(M_{X_2O_3}=\dfrac{32}{0,2}=160\left(g\right)\)
Ta có: \(M_{X_2O_3}=NTK_X.2+16.3=160\left(g\right)\)
=> NTKX = 56(đvC)
Vậy X là sắt (Fe)
=> CTHH là Fe2O3
![](https://rs.olm.vn/images/avt/0.png?1311)
\(m_{CH_3COOH}=12\%.100=12\left(g\right)\\ n_{CH_3COOH}=\dfrac{12}{60}=0,2\left(mol\right)\)
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`
`mCH3COOH = 100x12/100 = 12` (g)
`==> nCH3COOH = m/M = 12/60 = 0.2` (mol)
Theo pt: `=> nNaHCO3 = 0.2` (mol)
`==> mNaHCO3 = n.M = 0.2x84 =16.8` (g)
`==> mdd NaHCO3 = 16.8x100/8.4 = 200` (g)
Ta có: `nCH3COONa = 0.2` (mol)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a.n_{CO_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\\ a.Ca\left(OH\right)_2+CO_2\rightarrow CaCO_3+H_2O\\ 0,25.......0,25............0,25..........0,25\left(mol\right)\\ C_{MddCa\left(OH\right)_2}=\dfrac{0,25}{0,1}=2,5\left(M\right)\\ b.m_{\downarrow}=m_{CaCO_3}=100.0,25=25\left(g\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
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 :
\(C\%_{CH_3COOH} = \dfrac{0,25.60}{100}.100\% = 15\%\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(n_{HCl}=0,1.0,2=0,02\left(mol\right)\)
Pt : \(2HCl+Ca\left(OH\right)_2\rightarrow CaCl_2+2H_2O\)
0,02---->0,01---------->0,01
a) Nồng độ mol đề cho rồi mà nhỉ
b) \(m_{muôi}=m_{CaCl2}=0,01.111=1,11\left(g\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a, \(n_{KOH}=\dfrac{8,4}{56}=0,15\left(mol\right)\)
PT: \(CH_3COOH+KOH\rightarrow CH_3COOK+H_2O\)
Theo PT: \(n_{CH_3COOH}=n_{KOH}=0,15\left(mol\right)\Rightarrow C_{M_{CH_3COOH}}=\dfrac{0,15}{0,5}=0,3\left(M\right)\)
b, \(n_{Na_2CO_3}=0,2.0,5=0,1\left(mol\right)\)
PT: \(2CH_3COOH+Na_2CO_3\rightarrow2CH_3COONa+CO_2+H_2O\)
Xét tỉ lệ: \(\dfrac{0,15}{2}< \dfrac{0,1}{1}\), ta được Na2CO3 dư.
Theo PT: \(n_{CO_2}=\dfrac{1}{2}n_{CH_3COOH}=0,075\left(mol\right)\Rightarrow V_{CO_2}=0,075.22,4=1,68\left(l\right)\)
Giả sử có 100g dd CH3COOH 15%
Ta có:
\(n_{CH3COOH}=\frac{100.15\%}{60}=0,25\left(mol\right)\)
\(PTHH:Ca\left(OH\right)_2+2CH_3COOH\rightarrow\left(CH_3COO\right)_2Ca+2H_2O\)
\(\Rightarrow n_{Ca\left(OH\right)2}=n_{\left(CH3COO\right)2Ca}=0,125\left(mol\right)\)
\(\Rightarrow m_{dd\left(Ca\left(OH\right)2\right)}=\frac{0,125.74}{x\%}=\frac{9,25}{x\%}\)
\(\Rightarrow m_{dd\left(spu\right)}=\frac{9,25}{x\%+100}\Leftrightarrow C\%=9,875\%\)
\(\frac{0,125.158.100}{\frac{9,25}{x\%+100}}=9,875\Leftrightarrow x=9,25\)