để trung hòa 56 gam dung dịch KOH 35% thì cần bao nhiêu ml dd HCL 0,5 M? tính khối lượng muối thu được sau phản ứng
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a.250ml=0,25l ; nHCl=0,25.1,5=0,375mol
KOH+HCl->KCl+H2O
1mol 1mol 1mol
0,375 0,375 0,375
VKOh=0,375/2=0,1875l
b.CM KCL=0,375/0,25=1,5M
c.NaOH+HCL=NaCl+H2O
1mol 1mol
0,375 0,375
mdd NaOH=0,375.40.100/10=150g
Bài 1:
Ta có: \(n_{HCl}=0,2.0,5=0,1\left(mol\right)\)
BTNT H, có: \(n_{HCl}=2n_{H_2O}\Rightarrow n_{H_2O}=0,05\left(mol\right)\)
Theo ĐL BTKL, có: m oxit + mHCl = mmuối + mH2O
⇒ mmuối = 2,8 + 0,1.36,5 - 0,05.18 = 5,55 (g)
Bài 2:
\(m_{KOH}=200.5,6\%=11,2\left(g\right)\Rightarrow n_{KOH}=\dfrac{11,2}{56}=0,2\left(mol\right)\)
PT: \(2KOH+CuCl_2\rightarrow2KCl+Cu\left(OH\right)_2\)
Theo PT: \(n_{Cu\left(OH\right)_2}=\dfrac{1}{2}n_{KOH}=0,1\left(mol\right)\)
\(\Rightarrow m_{Cu\left(OH\right)_2}=0,1.98=9,8\left(g\right)\)
\(\text{1)}m_{KOH}=40.35\%=14\left(g\right)\\ \rightarrow n_{KOH}=\dfrac{14}{56}=0,25\left(mol\right)\\ PTHH:KOH+HCl\rightarrow KCl+H_2O\\ \text{Theo pthh}:n_{HCl}=n_{KOH}=0,25\left(mol\right)\\ \rightarrow V_{ddHCl}=0,25.0,5=0,125\left(l\right)\)
\(\text{2)}n_{Al}=\dfrac{4,05}{27}=0,15\left(mol\right)\\ n_{H_2SO_4}=200.14,7\%=29,4\left(g\right)\\ \rightarrow n_{H_2SO_4}=\dfrac{29,4}{98}=0,3\\ \text{PTHH}:2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\uparrow\\ \text{LTL}:\dfrac{0,15}{2}< \dfrac{0,3}{3}\rightarrow H_2SO_4\text{ dư}\)
\(\text{Theo pthh}:\left\{{}\begin{matrix}n_{H_2SO_4\left(pư\right)}=\dfrac{3}{2}n_{Al}=\dfrac{3}{2}.0,15=0,225\left(mol\right)\\n_{H_2}=n_{H_2SO_4\left(pư\right)}=0,225\left(mol\right)\\n_{Al_2\left(SO_4\right)_3}=\dfrac{1}{2}n_{Al}=\dfrac{1}{2}.0,15=0,075\left(mol\right)\end{matrix}\right.\\ \rightarrow m_{dd\left(\text{sau phản ứng}\right)}=200+4,05-0,3.2=203,45\left(g\right)\)
\(\rightarrow\left\{{}\begin{matrix}C\%_{H_2SO_4\text{ dư}}=\dfrac{\left(0,3-0,225\right).98}{203,45}=3,61\%\\C\%_{Al_2\left(SO_4\right)_3}=\dfrac{342.0,075}{203,45}=12,61\%\end{matrix}\right.\)
mKOH = mdd .35% = 19,6 (g)
⇒ nKOH = \(\frac{19,6}{56}=0,35\left(mol\right)\)
KOH + HCl → KCl + H2O
0,35 0,35 0,35
\(V_{HCl}=\frac{n}{C_M}=0,7\left(l\right)=700\left(ml\right)\)
mKCl = 0,35.74,5 = 26,075(mol)