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![](https://rs.olm.vn/images/avt/0.png?1311)
a, PT: \(Fe+2HCl\rightarrow FeCl_2+H_2\)
\(Mg+2HCl\rightarrow MgCl_2+H_2\)
b, Gọi: \(\left\{{}\begin{matrix}n_{Fe}=x\left(mol\right)\\n_{Mg}=y\left(mol\right)\end{matrix}\right.\)
Theo PT: \(\left\{{}\begin{matrix}n_{HCl}=2n_{Fe}+2n_{Mg}=2x+2y\left(mol\right)\\n_{H_2}=n_{Fe}+n_{Mg}=x+y\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow m_{HCl}=36,5.\left(2x+2y\right)=73\left(x+y\right)\left(g\right)\)
\(\Rightarrow m_{ddHCl}=\dfrac{73\left(x+y\right)}{20\%}=365\left(x+y\right)\left(g\right)\)
Ta có: m dd sau pư = mFe + mMg + m dd HCl - mH2 = 56x + 24y + 365.(x+y) - 2.(x+y) = 419x + 387y (g)
Theo PT: \(n_{MgCl_2}=n_{Mg}=y\left(mol\right)\)
\(C\%_{MgCl_2}=11,87\%\) \(\Rightarrow\dfrac{95y}{419x+387y}=0,1187\)
\(\Rightarrow\dfrac{x}{y}=0,9865\Rightarrow x=0,9865y\)
Theo PT: \(n_{FeCl_2}=n_{Fe}=x\left(mol\right)\)
\(\Rightarrow C\%_{FeCl_2}=\dfrac{127x}{419x+387y}.100\%=\dfrac{127.0,9865y}{419.0,9865y+387y}.100\%\approx15,65\%\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a. Ta có: mNaOH=\(\frac{200.20}{100}=40\left(g\right)\)
pt : NaOH + HCl --------> NaCl + H2O
theo pt: 40g 36,5g 58,5g 18g
theo đề: 40g 36,5g 58,5g
=>\(C_{\%}=\frac{58,5}{200+100}.100\%=19,5\%\)
b.\(C_{\%}=\frac{36,5}{100}.100\%=36,5\%\)
![](https://rs.olm.vn/images/avt/0.png?1311)
https://hoc24.vn/cau-hoi/cho-400-g-dung-dich-naoh-30-tac-dung-vua-het-voi-100-g-dung-dich-hcl-tinh-a-nong-do-muoi-thu-duoc-sau-phan-ungb-tinh-nong-do-axit-hcl-bie.7974814552205
Tui trả lời rùi nghen
![](https://rs.olm.vn/images/avt/0.png?1311)
\(n_{Zn}=\dfrac{6,5}{65}=0,1\left(mol\right)\)
\(n_{CuO}=\dfrac{20}{80}=0,25\left(mol\right)\)
PTHH: Zn + 2HCl ---> ZnCl2 + H2
0,1---->0,1----------------->0,1
=> \(\left\{{}\begin{matrix}V_{H_2}=0,1.22,4=2,24\left(l\right)\\C_{M\left(HCl\right)}=\dfrac{0,2}{0,2}=1M\end{matrix}\right.\)
PTHH: CuO + H2 --to--> Cu + H2O
LTL: 0,25 > 0,1 => CuO dư
Theo pthh: nCu = nH2 = 0,1 (mol)
=> mCu = 0,1.64 = 6,4 (g)
\(n_{Zn}=\dfrac{6,5}{65}=0,1\left(mol\right)\\
pthh:Zn+2HCl\rightarrow ZnCl_2+H_2\)
0,1 0,2 0,2
\(V_{H_2}=0,2.22,4=4,48l\\
C_M=\dfrac{0,2}{0,2}=1M\\
n_{CuO}=\dfrac{20}{80}=0,25\left(G\right)\\
pthh:CuO+H_2\underrightarrow{t^o}Cu+H_2O\\
LTL:0,25>0,1\)
=>CuO dư
\(n_{Cu}=n_{H_2}=0,1\left(mol\right)\\
m_{Cu}=0,1.64=6,4g\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a.Mg+2HCl->MgCl_2+H_2\\ Fe+2HCl->FeCl_2+H_2\\ b.Giả.sử:có:100g.dd.HCl\\ n_{HCl}=\dfrac{20\%.100}{36,5}=\dfrac{40}{73}mol\\ n_{Fe}=a;n_{Mg}=b\\ 2a+2b=\dfrac{40}{73}\\ BTKL:m_{ddsau}=56a+24b+100-2\left(a+b\right)=54a+22b+100\left(g\right)\\ C\%_{MgCl_2}=\dfrac{95b}{54a+22b+100}=\dfrac{11,787}{100}\\ -54a+783,97b=100\\ a=b=0,137\left(mol\right)\\ C\%FeCl_2=\dfrac{0,137\cdot127}{\dfrac{95\cdot0,137}{11,787\%}}\cdot100\%=15,757\%\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)Khối lượng của dd NaOH:
\(m_{NaOH}=\dfrac{m_{dd}.C\%}{100\%}=\dfrac{400.30\%}{100\%}=120\left(g\right)\)
Số mol của 400 g dd NaOH:
\(n_{NaOH}=\dfrac{m}{M}=\dfrac{120}{40}=3\left(mol\right)\)
PTHH:
\(NaOH+HCl\rightarrow NaCl+H_2O\)
1 : 1 : 1 : 1
3 -> 3 : 3 : 3 (mol)
Khối lượng của 3 mol NaCl:
\(m_{NaCl}=n.M=3.36,5=109,5\left(g\right)\)
Khối lượng của dd NaCl sau P.Ư:
\(m_{ddNaCl}=m_{ct}+m_{dm}=100+400=500\left(g\right)\)
Nồng độ % của dd NaCl:
\(C\%_{NaCl}=\dfrac{m_{ct}}{m_{dm}}.100\%=\dfrac{3.58,5}{500}.100\%=35,1\%\)
b, Nồng độ phần trăm của Axit:
\(C\%_{HCl}=\dfrac{m_{ct}}{m_{dd}}.100\%=\dfrac{3.36,5}{500}.100\%=21,9\%\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(n_{Zn}=\dfrac{6.5}{65}=0.1\left(mol\right)\)
\(Zn+2HCl\rightarrow ZnCl_2+H_2\)
\(0.1.....0.2...........0.1..........0.1\)
\(m_{HCl}=0.2\cdot36.5=7.3\left(g\right)\)
\(m_{\text{dung dịch sau phản ứng}}=6.5+146-0.1\cdot2=152.3\left(g\right)\)
\(C\%_{ZnCl_2}=\dfrac{136\cdot0.1}{152.3}\cdot100\%=8.92\%\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(n_{NaOH}=\dfrac{20\%.200}{40}=1\left(mol\right)\\ NaOH+HCl\rightarrow NaCl+H_2O\\ n_{NaCl}=n_{HCl}=n_{NaOH}=1\left(mol\right)\\ a,m_{ddNaCl}=200+100=300\left(g\right)\\ C\%_{ddNaCl}=\dfrac{58,5.1}{300}.100=19,5\%\\ b,C\%_{ddHCl}=\dfrac{36,5.1}{100}.100=36,5\%\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\($a/$\\ Zn+2HCl \to ZnCl_2+H_2\\ b/\\ n_{Zn}=0,1(mol)\\ n_{HCl}=0,1.2=0,2(mol)\\ m_{ddHCl}=\frac{0,2.36,5.100}{7,3}=100(g)\\ C\%_{ZnCl_2}=\frac{0,1.136}{100+6,5-0,1.2}.100\%=12,8\%\)
\(a/\\ Zn+2HCl \to ZnCl_2+H_2\\ b/\\ n_{Zn}=\frac{6,5}{65}=0,1(mol)\\ n_{HCl}=0,2(mol)\\ m_{ddsaupu}=\frac{0,1.36,5.100}{7,3}+6,5-0,1.2=56,3(g)\\ C\%_{ZnCl_2}=\frac{0,1.136}{56,3}.100\%=24,16\%\)