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nK = 39 / 39=1 (mol)
Pt: 2K + 2H2O --> 2KOH + H2
1 mol--------------------------> 0,5 mol
mH2 = 0,5 . 2 = 1 (g)
mdd = mK + mnước - mH2 = 39 + 362 - 1 = 400 (g)
C% dd KOH = 39/400.100%=9,75%
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SO3 + H2O \(\rightarrow\) H2SO4
nSO3=\(\dfrac{200}{80}=2,5\left(mol\right)\)
Theo PTHH ta có:
nSO3=nH2SO4=2,5(mol)
mH2SO4=98.2,5=245(g)
mdd H2SO4 17 % =1000.1,12=1120(g)
mH2SO4trong dd=1120.\(\dfrac{17}{100}=190,4\left(g\right)\)
C% dd H2SO4 =\(\dfrac{245+190,4}{1120+200}.100\%=33\%\)
\(n_{SO_3}=\dfrac{200}{80}=2.5\left(mol\right)\)
\(m_{dd_{H_2SO_4}}=1000\cdot1.12=1120\left(g\right)\)
\(m_{H_2SO_4}=1120\cdot17\%=190.4\left(g\right)\)
\(SO_3+H_2O\rightarrow H_2SO_4\)
\(2.5.....................2.5\)
\(m_{H_2SO_4}=2.5\cdot98+190.4=435.4\left(g\right)\)
\(m_{dd_{H_2SO_4}}=200+1120=1320\left(g\right)\)
\(C\%_{H_2SO_4}=\dfrac{435.4}{1320}\cdot100\%=33\%\)
$SO_3 + H_2O \to H_2SO_4$
$n_{H_2SO_4} = n_{SO_3} = \dfrac{200}{80} = 2,5(mol)$
$m_{dd\ H_2SO_4\ 17\%} =1000.1,12 = 1120(gam)$
Sau khi pha :
$m_{dd} = 200 + 1120 = 1320(gam)$
$m_{H_2SO_4} = 1120.17\% + 2,5.98 = 435,4(gam)$
$C\%_{H_2SO_4} = \dfrac{435,4}{1320}.100\% = 33\%$
a, \(C\%_{KCl}=\dfrac{20}{20+60}.100\%=25\%\)
b, \(C\%=\dfrac{40}{40+150}.100\%\approx21,05\%\)
c, \(C\%_{NaOH}=\dfrac{60}{60+240}.100\%=20\%\)
d, \(C\%_{NaNO_3}=\dfrac{30}{30+90}.100\%=25\%\)
e, \(m_{NaCl}=150.60\%=90\left(g\right)\)
f, \(m_{ddA}=\dfrac{25}{10\%}=250\left(g\right)\)
g, \(n_{NaOH}=120.20\%=24\left(g\right)\)
Gọi: nNaOH (thêm vào) = a (g)
\(\Rightarrow\dfrac{a+24}{a+120}.100\%=25\%\Rightarrow a=8\left(g\right)\)
\(SO_3+H_2O\rightarrow H_2SO_4\)
\(n_{SO_3}=\dfrac{12}{80}=0,15\left(mol\right)\)
Theo PT: \(n_{H_2SO_4}=n_{SO_3}=0,15\left(mol\right)\)
\(\Rightarrow C\%_{H_2SO_4}=\dfrac{0,15.98}{12+100}.100\%=13,125\%\)
PTHH: \(SO_3+H_2O\rightarrow H_2SO_4\)
Ta có: \(n_{SO_3}=\dfrac{320}{80}=4\left(mol\right)=n_{H_2SO_4}\) \(\Rightarrow C\%_{H_2SO_4}=\dfrac{4\cdot98}{320+480}\cdot100\%=49\%\)
Dung dịch sau p/ứ làm quỳ tím hóa đỏ
gì mà 4 mol SO3 lận z
nSO3=4(mol)
PTHH: SO3 + H2O -> H2SO4
mH2O=480(g) => mddH2SO4=mSO3 + mH2O=800(g)
nH2SO4=nSO3=4(mol) => mH2SO4=392(g)
=> C%ddH2SO4= (392/800).100=49%
=> QUỲ TÍM HÓA ĐỎ LÈ LÈ NÈ
PTHH: \(K+H_2O\rightarrow KOH+\dfrac{1}{2}H_2\uparrow\)
a) Ta có: \(n_K=\dfrac{7,8}{39}=0,2\left(mol\right)\)
\(\Rightarrow\left\{{}\begin{matrix}n_{KOH}=0,2\left(mol\right)\\n_{H_2}=0,1\left(mol\right)\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{KOH}=0,2\cdot56=11,2\left(g\right)\\m_{H_2}=0,1\cdot2=0,2 \left(g\right)\end{matrix}\right.\)
Mặt khác: \(m_{dd\left(saup/ứ\right)}=m_K+m_{H_2O}-m_{H_2}=400\left(g\right)\)
\(\Rightarrow C\%_{KOH}=\dfrac{11,2}{400}\cdot100\%=2,8\%\)
b) Ta có: \(V_{dd\left(saup/ứ\right)}=\dfrac{400}{1,08}\approx370,37\left(ml\right)=0,37037\left(l\right)\)
\(\Rightarrow C_{M_{KOH}}=\dfrac{0,2}{0,37037}\approx0,54\left(M\right)\)
Câu 1:
nK = \(\dfrac{39}{39}=1\) mol
Pt: 2K + 2H2O --> 2KOH + H2
1 mol--------------------------> 0,5 mol
mH2 = 0,5 . 2 = 1 (g)
mdd = mK + mnước - mH2 = 39 + 362 - 1 = 400 (g)
C% dd KOH = \(\dfrac{39}{400}.100\%=9,75\%\)
Câu 2:
Đổi: 1 lít = 1000 ml
mdd H2SO4 = \(1000\times1,12=1120\left(g\right)\)
mH2SO4 = \(\dfrac{1120\times17}{100}=190,4\left(g\right)\)
=> mH2O = 1120 - 190,4 = 929,6 (g)
=> nH2O = \(\dfrac{929,6}{18}=51,64\) mol
nSO3 = \(\dfrac{200}{80}=2,5\) mol => nước dư
Pt: SO3 + H2O --> H2SO4 (1)
...2,5 mol----------> 2,5 mol
mH2SO4 (1) = 2,5 . 98 = 245 (g)
mH2SO4 sau khi hòa tan =245 + 190,4 = 435,4 (g)
mdd = 1120 + 200 = 1320 (g)
C% = \(\dfrac{435,4}{1320}.100\%=33\%\)