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\(a) n_{Na_2CO_3} = \dfrac{2,12}{106} = 0,02(mol) ; n_{HCl} = 0,5.0,1 = 0,05(mol)\\ Na_2CO_3 + 2HCl \to 2NaCl + CO_2 + H_2O\\ Vì :2n_{Na_2CO_3} = 0,04 < n_{HCl} = 0,05\ nên\ HCl\ \text{dư}\\ n_{CO_2} = n_{Na_2CO_3} = 0,02(mol)\\ V_{CO_2} = 0,02.22,4 = 0,448(lít)\\ b) n_{HCl\ dư} = n_{HCl\ ban\ đầu} - 2n_{Na_2CO_3} = 0,05 -0,02.2 = 0,01(mol)\\ n_{NaCl} = 2n_{Na_2CO_3} = 0,02.2 = 0,04(mol)\\ C_{M_{HCl}} = \dfrac{0,01}{0,5} = 0,02M\\ C_{M_{NaCl}} = \dfrac{0,04}{0,5} = 0,08M\)
a)
$Fe + H_2SO_4 \to FeSO_4 + H_2$
Theo PTHH :
$n_{Fe} = n_{H_2} = \dfrac{3,36}{22,4} = 0,15(mol)$
$m_{Fe} = 0,15.56 = 8,4(gam)$
b)
$n_{H_2SO_4} = n_{H_2} = 0,15(mol)$
$C_{M_{H_2SO_4}} = \dfrac{0,15}{0,05} = 3M$
c)
$n_{FeSO_4} = n_{H_2} = 0,15(mol)$
$C_{M_{FeSO_4}} = \dfrac{0,15}{0,05} = 3M$
\(n_{Al_2O_3}=\dfrac{18,36}{102}=0,18\left(mol\right)\\ n_{Al}=\dfrac{0,81}{27}=0,03\left(mol\right)\\ Al_2O_3+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2O\left(1\right)\\ 2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\left(2\right)\\ H_2SO_4+2NaOH\rightarrow Na_2SO_4+2H_2O\left(3\right)\\ n_{NaOH}=0,05.4=0,2\left(mol\right)\\ n_{H_2SO_4\left(dư\right)}=\dfrac{0,2}{2}=0,1\left(mol\right)\\ n_{Al_2\left(SO_4\right)_3}=0,18+0,5.0,03=0,195\left(mol\right)\\ m_{ddsau}=m_{hh}+m_{ddH_2SO_4}-m_{H_2}\\ =18,36+0,81+300-0,045.2=319,08\left(g\right)\\ C\%_{ddAl_2\left(SO_4\right)_3}=\dfrac{342.0,195}{319,08}.100\approx20,901\%\\ C\%_{ddH_2SO_4\left(dư\right)}=\dfrac{0,1.98}{319,08}.100\approx3,071\%\)
a) Đặt \(n_{CH_3COOH}=x\left(mol\right)\)
\( n_{H^+}=10^{-2,88}\cdot0,05=6,59\cdot10^{-5}\)
\(CH_3COOH\text{ }⇌\text{ }CH_3COO^-\text{ }+\text{ }H^+\)
Bd \(x\)
PL \(6,59\cdot10^{-5}\)_\(6,59\cdot10^{-5}\)__\(6,59\cdot10^{-5}\)
Sau \(x-6,59\cdot10^{-5}\)_\(6,59\cdot10^{-5}\)_\(6,59\cdot10^{-5}\)
\(\Rightarrow K_a=\frac{6,59\cdot10^{-5}\cdot6,59\cdot10^{-5}}{x-6,59\cdot10^{-5}}=10^{-4,76}\\ \Rightarrow x=3,16\cdot10^{-4}\)
b) \(NaOH+CH_3COOH\rightarrow CH_3COONa+H_2O\)
\(6,32\cdot10^{-4}\)___\(6,32\cdot10^{-4}\)
\(\Rightarrow n_{NaOH\left(dư\right)}=4,368\cdot10^{-3}\\ \Rightarrow pH=12,46\)