Cho 31g Na20 tác dụng với nước, thu được 500ml dd X
a) Viết PTHH và tính nồng độ mol của dd X thu được
b) tính thể tích dd H2SO4 20% có khối lượng riêng 1,14g/ml cần dùng để trung hòa dd X nói trên
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a, \(Na_2O+H_2O\rightarrow2NaOH\)
Ta có: \(n_{Na_2O}=\dfrac{15,5}{62}=0,25\left(mol\right)\)
Theo PT: \(n_{NaOH}=2n_{Na_2O}=0,5\left(mol\right)\)
\(\Rightarrow CM_{NaOH}=\dfrac{0,5}{0,5}=1\left(M\right)\)
b, \(2NaOH+H_2SO_4\rightarrow Na_2SO_4+2H_2O\)
Theo PT: \(n_{H_2SO_4}=\dfrac{1}{2}n_{NaOH}=0,25\left(mol\right)\)
\(\Rightarrow m_{ddH_2SO_4}=\dfrac{0,25.98}{20\%}=122,5\left(g\right)\)
\(\Rightarrow V_{ddH_2SO_4}=\dfrac{122,5}{1,14}\approx107,46\left(ml\right)\)
a, \(Na_2O+H_2O\rightarrow2NaOH\)
\(n_{Na_2O}=\dfrac{15,5}{62}=0,25\left(mol\right)\)
\(n_{NaOH}=2n_{Na_2O}=0,5\left(mol\right)\)
\(\Rightarrow C_{M_{NaOH}}=\dfrac{0,5}{0,5}=1\left(M\right)\)
b, \(H_2SO_4+2NaOH\rightarrow Na_2SO_4+2H_2O\)
\(n_{H_2SO_4}=\dfrac{1}{2}n_{NaOH}=0,25\left(mol\right)\)
\(\Rightarrow m_{ddH_2SO_4}=\dfrac{0,25.98}{20\%}=122,5\left(g\right)\)
\(\Rightarrow V_{ddH_2SO_4}=\dfrac{122,5}{1,14}\approx107,46\left(ml\right)\)
BaO+H2O -> Ba(OH)2
0,02 0,02
a) CM = n/V = 0,02/0,02 = 1M
b) Ba(OH)2 + H2SO4 -> BaSO4 +2H2O
0,02 0,02
=> m = 0,392 g
D = m/V = 1,14
=> 0,392/V = 1,14 => V = 0,34l
a)
$n_{Na_2O} = \dfrac{15,5}{62} = 0,25(mol)$
$Na_2O + H_2O \to 2NaOH$
$n_{NaOH} = 2n_{Na_2O} = 0,5(mol)$
$C_{M_{NaOH}} = \dfrac{0,5}{0,5} = 1M$
b)
$2NaOH + H_2SO_4 \to Na_2SO_4 + 2H_2O$
$n_{H_2SO_4} = \dfrac{1}{2}n_{NaOH} = 0,25(mol)$
$\Rightarrow m_{dd\ H_2SO_4} = \dfrac{0,25.98}{20\%} = 122,5(gam)$
$\Rightarrow V_{dd\ H_2SO_4} = \dfrac{122,5}{1,14} = 107,46(ml)$
Bài 4:
PTHH: \(Na_2O+H_2O\rightarrow2NaOH\)
\(2NaOH+H_2SO_4\rightarrow Na_2SO_4+2H_2O\)
a) Ta có: \(n_{Na_2O}=\dfrac{15,5}{62}=0,25\left(mol\right)\) \(\Rightarrow n_{NaOH}=0,5\left(mol\right)\)
\(\Rightarrow C_{M_{NaOH}}=\dfrac{0,5}{0,5}=1\left(M\right)\)
b) Theo PTHH: \(n_{H_2SO_4}=\dfrac{1}{2}n_{NaOH}=0,25\left(mol\right)\)
\(\Rightarrow m_{ddH_2SO_4}=\dfrac{0,25\cdot98}{20\%}=122,5\left(g\right)\) \(\Rightarrow V_{ddH_2SO_4}=\dfrac{122,5}{1,14}\approx107,46\left(ml\right)\)
a)
$Na_2O + H_2O \to 2NaOH$
n Na2O = 15,5/62 = 0,25(mol)
n NaOH = 2n Na2O = 0,5(mol)
=> CM NaOH = 0,5/0,5 = 1M
b) $2NaOH + H_2SO_4 \to Na_2SO_4 + 2H_2O$
n H2SO4 = 1/2 n NaOH = 0,25(mol)
=> m dd H2SO4 = 0,25.98/20% = 122,5(gam)
=> V dd H2SO4 = m / D = 122,5/1,14 =107,46(ml)
c) n Na2SO4 = n H2SO4 = 0,25(mol)
CM Na2SO4 = 0,25/0,10746 = 2,33M
a)
`\(Na_2O++H_{2_{ }}O->2NaOH\)
\(n_{Na_2O}=\dfrac{15,5}{62}=0,25mol\)
\(n_{Na_2O}=2n_{Na_2O}=0,5mol\)
\(C_{M_{NaOH}}=\dfrac{0,5}{0,5}\)=1M
a)
\(n_{Na_2O}=\dfrac{31}{62}=0,5\left(mol\right)\)
PTHH: Na2O + H2O --> 2NaOH
______0,5--------------->1
=> \(C_{M\left(NaOH\right)}=\dfrac{1}{0,5}=2M\)
b)
PTHH: H2SO4 + 2NaOH --> Na2SO4 + 2H2O
______0,5<---------1
=> mH2SO4 = 0,5.98 = 49(g)
=> \(m_{dd\left(H_2SO_4\right)}=\dfrac{49.100}{20}=245\left(g\right)\)
=> \(V_{dd\left(H_2SO_4\right)}=\dfrac{245}{1,14}=214,912\left(ml\right)\)
\(n_{Na_2O}=\dfrac{31}{62}=0,5(mol)\\ a,Na_2O+H_2O\to 2NaOH\\ \Rightarrow n_{NaOH}=1(mol)\\ \Rightarrow C_{M_{NaOH}}=\dfrac{1}{0,5}=2M\\ b,2NaOH+H_2SO_4\to Na_2SO_4+2H_2O\\ \Rightarrow n_{H_2SO_4}=0,5(mol)\\ \Rightarrow m_{dd_{H_2SO_4}}=\dfrac{0,5.98}{20\%}=245(g)\\ \Rightarrow V_{dd_{H_2SO_4}}=\dfrac{245}{1,14}=214,91(ml)\)