B1: cần lấy bao nhiêu gam H2SO4.3SO3 vào 600g dung dịch H2SO4 2M (d =1.2g/ml) để thu được dung dịch H2SO4 98%
B2: cần lấy bao nhiêu gam H2SO4.3SO3 và bao nhiêu gam dung dịch H2SO4 15%để thu được dung dịch H2SO4 35% (d =1.2g /ml)
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\(m_{ddH_2SO_4\left(95\%\right)}=a\left(g\right);m_{ddH_2SO_4\left(10\%\right)}=b\left(g\right)\\ m_{ddH_2SO_4\left(25\%\right)}=1,15.50=57,5\left(g\right)\\ \rightarrow\left\{{}\begin{matrix}a+b=57,5\\0,95a+0,1b=57,5.25\%\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=10,147\\b=47,353\end{matrix}\right.\)
=> Cần khoảng 10,147 gam dd H2SO4 95% trộn với khoảng 47,353 gam dd H2SO4 10%
Bài 10:
- Giả sử có 100 gam dd H2SO4 98%
\(m_{H_2SO_4}=\dfrac{100.98}{100}=98\left(g\right)\) => \(n_{H_2SO_4}=\dfrac{98}{98}=1\left(mol\right)\)
\(V_{dd.H_2SO_4.98\%}=\dfrac{100}{1,84}=\dfrac{1250}{23}\left(ml\right)=\dfrac{5}{92}\left(l\right)\)
\(C_{M\left(dd.H_2SO_4.98\%\right)}=\dfrac{1}{\dfrac{5}{92}}=18,4M\)
\(n_{H_2SO_4}=18,4.0,05=0,92\left(mol\right)\)
=> \(m_{H_2SO_4}=0,92.98=90,16\left(g\right)\)
=> \(m_{dd.H_2SO_4.10\%}=\dfrac{90,16.100}{10}=901,6\left(g\right)\)
Bài 11:
a) Do dd sau pư có 3 chát tan với nồng độ % bằng nhau
=> \(m_{Al_2\left(SO_4\right)_3}=m_{ZnSO_4}=m_{H_2SO_4\left(dư\right)}\)
Gọi số mol Al, Zn là a, b (mol)
PTHH: 2Al + 3H2SO4 --> Al2(SO4)3 + 3H2
a----->1,5a------->0,5a----->1,5a
Zn + H2SO4 --> ZnSO4 + H2
b----->b--------->b----->b
=> \(\left\{{}\begin{matrix}m_{Al_2\left(SO_4\right)_3}=342.0,5a=171a\left(g\right)\\m_{ZnSO_4}=161b\left(g\right)\end{matrix}\right.\)
=> 171a = 161b
=> \(\dfrac{a}{b}=\dfrac{161}{171}\) (1)
Có: \(\dfrac{m_{Al}}{m_{Zn}}=\dfrac{27.n_{Al}}{65.n_{Zn}}=\dfrac{27}{65}.\dfrac{161}{171}=\dfrac{483}{1235}\)
b) \(n_{H_2}=1,5a+b=\dfrac{11,2}{22,4}=0,5\left(mol\right)\) (2)
(1)(2) => \(\left\{{}\begin{matrix}a=\dfrac{161}{825}\left(mol\right)\\b=\dfrac{57}{275}\left(mol\right)\end{matrix}\right.\)
=> \(x=\dfrac{161}{825}.27+\dfrac{57}{275}.65=\dfrac{5154}{275}\left(g\right)\)
\(m_{H_2SO_4\left(dư\right)}=m_{Al_2\left(SO_4\right)_3}=342.0,5\dfrac{161}{825}=\dfrac{9177}{275}\left(g\right)\)
=> \(m_{H_2SO_4\left(bđ\right)}=98\left(1,5a+b\right)+\dfrac{9177}{275}=\dfrac{22652}{275}\left(g\right)\)
=> \(y=\dfrac{\dfrac{22652}{275}.100}{10}=\dfrac{45304}{55}\left(g\right)\)
Gọi
\(n_{SO_3}=a\left(mol\right)\\ \rightarrow m_{dd\left(sau\right)}=600+80a\left(g\right)\\ PTHH:SO_3+H_2O\rightarrow H_2SO_4\\ Mol:a\rightarrow a\rightarrow a\\ m_{H_2SO_4\left(bđ\right)}=24,5\%.600=147\left(g\right)\\ \rightarrow C\%_{H_2SO_4\left(sau\right)}=\dfrac{146+98a}{600+80a}=49\%\\ \Leftrightarrow n_{SO_3}=2,5\left(mol\right)\\ \rightarrow m_{SO_3}=2,5.80=200\left(g\right)\)
Gọi \(n_{SO_3}=a\left(mol\right)\)
\(\rightarrow m_{dd\left(sau.khi.hoà.tan.thêm\right)}=600+80a\left(g\right)\)
\(PTHH:SO_3+H_2O\rightarrow H_2SO_4\)
a a
\(m_{H_2SO_4\left(bđ\right)}=24,5\%.600=147\left(g\right)\\ \rightarrow C\%_{H_2SO_4\left(sau.khi.pha\right)}=\dfrac{147+98a}{600+a}=49\%\\ \Leftrightarrow a\approx1,51\left(mol\right)\\ \rightarrow m_{SO_3}=1,51.80=120,8\left(g\right)\)
Gọi mdd H2SO4 10% = x (g)
Ta có: mH2SO4 25% = \(\frac{150.25}{100}\) = 37,5 g
mdd H2SO4 15% = x + 150
mH2SO4 15% = \(\frac{10x}{100}\) +37,5= 0,1x + 37,5
Ta có: C% dd sau p.ứng =\(\frac{m_{ct}}{m_{dd}}.100\)
⇔⇔ 15 =\(\frac{0,1x+37,5}{x+150}.100\)
⇔⇔ 0,15 = \(\frac{0,1x+37,5}{x+150}\)
⇔⇔ 0,15x + 22,5 = 0,1x + 37,5
⇔⇔ 0,05x = 15
⇔⇔ x = 300g = mdd H2SO4 10%
Gọi mdd H2SO4 10% = x (g)
Ta có: mH2SO4 25% = \(^{\frac{150}{25}.100}\) = 37,5 g
mdd H2SO4 15% = x + 150
mH2SO4 15% = \(\frac{10.x}{100}\) + 37,5 = 0,1x + 37,5
Ta có: C% dd sau p.ứng = \(\frac{m_{ct}}{m_{dd}}.100\)
\(\Leftrightarrow\) 15 = \(\frac{0,1x+37,5}{x+150}.100\)
\(\Leftrightarrow\) 0,15 = \(\frac{0,1x+37,5}{x+150}\)
\(\Leftrightarrow\) 0,15x + 22,5 = 0,1x + 37,5
\(\Leftrightarrow\) 0,05x = 15
\(\Leftrightarrow\) x = 300g = mdd H2SO4 10%
\(m_{dd\ H_2SO_4} = D.V = 1,31.100 = 131(gam)\\ \Rightarrow m_{H_2SO_4} = 131.40\% = 52,4(gam)\\ \Rightarrow m_{H_2O} = 131-52,4 = 78,6\ gam\\ \Rightarrow n_{H_2O} = \dfrac{78,6}{18}=\dfrac{131}{30}(mol)\\ n_{oleum} = x(mol) \Rightarrow n_{SO_3} = 3x(mol)\\ SO_3 + H_2O\to H_2SO_4\\ n_{SO_3\ pư} = n_{H_2O} = \dfrac{131}{30}\ mol\\ n_{SO_3\ dư} = 3x - \dfrac{131}{30}\ mol\\ m_{oleum} = 131 + 338x(gam)\\ \)
\(\eqalign{ & \% {m_{S{O_3}}} = {{\left( {3x - {{131} \over {30}}} \right).80} \over {131 + 338x}}.100\% = 10\% \cr & \Rightarrow x = 1,7577 \cr & \Rightarrow {m_{{H_2}S{O_4}.3S{O_3}}} = 338.1,7577 = 594(g) \cr}\)