cho 24 g Mg tác dụng hoàn toàn với 200 ml dd Aixit Clohiđric a,tính thể tích khí thoát ra ở điều kiện tiêu chuẩn.b, tính nồng độ mol của dd axit Clohiđric cần dùng
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Khí sinh ra có dkhí/H2 = 15 ⇒ M khí = 15.2 = 30 (g/mol)
→ NO
Ta có: \(n_{Cu}=\dfrac{1,92}{64}=0,03\left(mol\right)\)
\(n_{KNO_3}=0,1.0,1=0,01\left(mol\right)=n_{NO_3^-}\)
\(n_{H_2SO_4}=0,1.0,16=0,016\left(mol\right)\Rightarrow n_{H^+}=0,016.2=0,032\left(mol\right)\)
\(3Cu+8H^++2NO_3^-\rightarrow3Cu^{2+}+2NO+4H_2O\)
⇒ nNO = 0,008 (mol)
⇒ VH2 = 0,008.22,4 = 0,1792 (l)
a, \(n_{MgCO_3}=\dfrac{8,4}{84}=0,1\left(mol\right)\)
PT: \(MgCO_3+2HCl\rightarrow MgCl_2+CO_2+H_2O\)
Theo PT: \(n_{CO_2}=n_{MgCO_3}=0,1\left(mol\right)\)
\(\Rightarrow V_{CO_2}=0,1.22,4=2,24\left(l\right)\)
b, \(n_{KOH}=50.33,6\%=16,8\left(g\right)\Rightarrow n_{KOH}=\dfrac{16,8}{56}=0,3\left(mol\right)\)
\(\Rightarrow\dfrac{n_{KOH}}{n_{CO_2}}=\dfrac{0,3}{0,1}=3\) → pư tạo muối K2CO3 và KOH dư.
PT: \(CO_2+2KOH\rightarrow K_2CO_3+H_2O\)
Theo PT: \(n_{K_2CO_3}=n_{CO_2}=0,1\left(mol\right)\)
\(\Rightarrow m_{K_2CO_3}=0,1.138=13,8\left(g\right)\)
\(K_2O+H_2O\rightarrow2KOH\)
\(2KOH+CO_2\rightarrow K_2CO_3+H_2O\)
\(K_2CO_3+2HCl\rightarrow2KCl+CO_2+H_2O\)
\(KCl+AgNO_3\rightarrow KNO_3+AgCl\)
a, \(MgCl_2+2NaOH\rightarrow Mg\left(OH\right)_2+2NaCl\)
\(Mg\left(OH\right)_2\underrightarrow{t^o}MgO+H_2O\)
b, \(n_{MgCl_2}=0,2.0,25=0,05\left(mol\right)\)
Theo PT: \(n_{MgO}=n_{Mg\left(OH\right)_2}=n_{MgCl_2}=0,05\left(mol\right)\)
\(\Rightarrow m_{MgO}=0,05.40=2\left(g\right)\)
c, \(n_{NaOH}=2n_{MgCl_2}=0,1\left(mol\right)\)
\(\Rightarrow m_{ddNaOH}=\dfrac{0,1.40}{15\%}=\dfrac{80}{3}\left(g\right)\)
a, PT: \(2KClO_3\underrightarrow{t^o}2KCl+3O_2\)
Ta có: \(n_{KCl}=\dfrac{1,49}{74,5}=0,02\left(mol\right)\)
Theo PT: \(n_{O_2}=\dfrac{3}{2}n_{KCl}=0,03\left(mol\right)\)
\(\Rightarrow V_{O_2}=0,03.24,79=0,7437\left(l\right)\)
b, Theo PT: \(n_{KClO_3\left(TT\right)}=n_{KCl}=0,02\left(mol\right)\)
\(\Rightarrow m_{KClO_3\left(TT\right)}=0,02.122,5=2,45\left(g\right)\)
\(\Rightarrow H=\dfrac{2,45}{3,5}.100\%=70\%\)
a, \(n_{CuO}=\dfrac{4}{80}=0,05\left(mol\right)\)
PT: \(Cu\left(OH\right)_2\underrightarrow{t^o}CuO+H_2O\)
Theo PT: \(n_{Cu\left(OH\right)_2}=n_{CuO}=0,05\left(mol\right)\)
\(\Rightarrow m_{Cu\left(OH\right)_2}=0,05.98=4,9\left(g\right)\)
b, \(m_{H_2SO_4}=250.9,8\%=24,5\left(g\right)\Rightarrow n_{H_2SO_4}=\dfrac{24,5}{98}=0,25\left(mol\right)\)
PT: \(Cu\left(OH\right)_2+H_2SO_4\rightarrow CuSO_4+2H_2O\)
Xét tỉ lệ: \(\dfrac{0,05}{1}< \dfrac{0,25}{1}\), ta được H2SO4 dư.
Theo PT: \(n_{CuSO_4}=n_{H_2SO_4\left(pư\right)}=n_{Cu\left(OH\right)_2}=0,05\left(mol\right)\)
\(\Rightarrow n_{H_2SO_4\left(dư\right)}=0,25-0,05=0,2\left(mol\right)\)
\(\Rightarrow\left\{{}\begin{matrix}C\%_{CuSO_4}=\dfrac{0,05.160}{4,9+250}.100\%\approx3,14\%\\C\%_{H_2SO_4\left(dư\right)}=\dfrac{0,2.98}{4,9+250}.100\%\approx7,69\%\end{matrix}\right.\)
a, \(2NaOH+H_2SO_4\rightarrow Na_2SO_4+2H_2O\)
\(2KOH+H_2SO_4\rightarrow K_2SO_4+2H_2O\)
Ta có: 40nNaOH + 56nKOH = 25,44 (1)
\(n_{H_2SO_4}=\dfrac{1}{2}n_{NaOH}+\dfrac{1}{2}n_{KOH}=0,3.0,9=0,27\left(mol\right)\left(2\right)\)
Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}n_{NaOH}=0,3\left(mol\right)\\n_{KOH}=0,24\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}m_{NaOH}=0,3.40=12\left(g\right)\\m_{KOH}=0,24.56=13,44\left(g\right)\end{matrix}\right.\)
b, \(m_{ddH_2SO_4}=300.1,14=342\left(g\right)\)
\(\Rightarrow C\%_{H_2SO_4}=\dfrac{0,27.98}{342}.100\%\approx7,74\%\)
\(n_{Mg}=\dfrac{24}{24}=1\left(mol\right)\)
PT: \(Mg+2HCl\rightarrow MgCl_2+H_2\)
a, \(n_{H_2}=n_{Mg}=1\left(mol\right)\Rightarrow V_{H_2}=1.22,4=22,4\left(l\right)\)
b, \(n_{HCl}=2n_{Mg}=2\left(mol\right)\Rightarrow C_{M_{HCl}}=\dfrac{2}{0,2}=10\left(M\right)\)