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\(n_{H_2SO_4}=\dfrac{4,9}{98}=0,05\left(mol\right)\\ H_2SO_4+2NaOH\rightarrow Na_2SO_4+2H_2O\\ a,n_{NaOH}=n_{H_2O}2.0,05=0,1\left(mol\right)\\ \Rightarrow m_{NaOH}=0,1.40=4\left(g\right)\\ b,C1:n_{Na_2SO_4}=n_{H_2SO_4}=0,05\left(mol\right)\\ m_{sp}=m_{Na_2SO_4}+m_{H_2O}=0,05.142+18.0,1=8,9\left(g\right)\\ C2:m_{sp}=m_{H_2SO_4}+m_{NaOH}=4,9+4=8,9\left(g\right)\)
a, \(Na_2O+H_2SO_4\rightarrow Na_2SO_4+H_2O\)
b, Số mol \(H_2SO_4\) là: \(n_1=V.C_M=0,5.0,5=0,25\) (mol)
Số mol \(Na_2SO_4\) là \(n_2=\dfrac{28,4}{142}=0,2\) (mol)
Do \(n_2< n_1\) nên \(H_2SO_4\) còn dư
Suy ra số mol \(Na_2O\) tham gia phản ứng là: \(n=n_2=0,2\) (mol)
Khối lượng là: \(m_{Na_2O}=0,2.62=12,4g\)
nNa2CO3= 25/106(mol)
PTHH: Na2CO3 + 2 HCl -> 2 NaCl + CO2 + H2O
a) nHCl=25/106 . 2= 25/53 (mol)
=> m=mddHCl={[25/53].36,5]/15%}=114,78(g)
b) nCO2= 25/106 x 22,4= 5,28(l)
c) mNaCl=25/53. 58,5=27,59(g)
mddNaCl=25+114,78- 25/106.44=129,4(g)
=>C%ddNaCl=(27,59/129,4).100=21,32%
\(n_{Na}=\dfrac{2,3}{23}=0,1mol\)
\(n_{H_2O}=\dfrac{47,8}{18}=2,65mol\)
\(2Na+2H_2O\rightarrow2NaOH+H_2\)
0,1 < 2,65 ( mol )
0,1 0,1 0,05 ( mol )
\(m_{NaOH}=0,1.40=4g\)
\(m_{ddspứ}=2,3+47,8-0,05.2=50g\)
\(C\%_{NaOH}=\dfrac{4}{50}.100=8\%\)
\(a) 4Na + O_2 \xrightarrow{t^o} 2Na_2O\\ b) n_{Na} = \dfrac{4,6}{23} = 0,2(mol)\\ n_{O_2} = \dfrac{1}{4}n_{Na} = 0,05(mol)\\ V_{O_2} = 0,05.22,4 = 1,12(lít)\\ c) Na_2O + H_2O \to 2NaOH\\ n_{NaOH} = n_{Na} = 0,2(mol)\\ C\%_{NaOH} = \dfrac{0,2.40}{160}.100\% = 5\%\\ d)\)
\(n_{Na\ thêm} = x(mol)\\ 2Na + 2H_2O \to 2NaOH + H_2\\ n_{NaOH} = n_{Na} = x(mol)\\ n_{H_2} =0,5x(mol)\\ \Rightarrow m_{dd} = 23x + 160 -0,5x.2 = 22x + 160(gam)\\ \Rightarrow C\% = \dfrac{0,2.40 + 40x}{22x + 160}.100\% = 5\% + 5\%\\ \Rightarrow x = \dfrac{40}{189}\\ m_{Na} = \dfrac{40}{189}.23 = 4,87(gam)\)
\(n_{Na}=\dfrac{4.6}{23}=0.2\left(mol\right)\)
\(4Na+O_2\underrightarrow{^{t^0}}2Na_2O\)
\(0.2.....0.05.........0.1\)
\(V_{O_2}=0.05\cdot22.4=1.12\left(l\right)\)
\(Na_2O+H_2O\rightarrow2NaOH\)
\(0.1.......................0.2\)
\(m_{NaOH}=0.2\cdot40=8\left(g\right)\)
\(C\%_{NaOH}=\dfrac{8}{160}\cdot100\%=5\%\)
Để C% tăng thêm 5%
\(Na+H_2O\rightarrow NaOH+\dfrac{1}{2}H_2\)
\(a...............a.......0.5a\)
\(m_{NaOH}=40a\left(g\right)\)
\(m_{dd_{NaOH}}=23a+160-0.5a\cdot2=22a+160\left(g\right)\)
\(C\%_{NaOH}=\dfrac{40a+8}{22a+160}\cdot100\%=5\%\)
\(\Rightarrow a=0\)
=> Sai đề
Câu 1:
\(\text{a) }pthh:CaCO3+2HCl\rightarrow CaCl_2+CO_2+H_2O\left(1\right)\\ NaOH+HCl\rightarrow NaCl+H_2O\left(2\right)\)
b) \(n_{NaOH}=C_M\cdot V=0,05\cdot2=0,1\left(mol\right)\)
Theo \(pthh\left(2\right):n_{HCl\left(2\right)}=n_{NaOH}=0,1\left(mol\right)\)
\(m_{HCl}=\dfrac{m_{d^2HCl}\cdot C\%}{100}=\dfrac{200\cdot10,95}{100}=21,9\left(g\right)\\ \Rightarrow n_{HCl}=\dfrac{m}{M}=\dfrac{21,9}{36,5}=0,6\left(mol\right)\\ \Rightarrow n_{HCl\left(1\right)}=0,6-0,1=0,5\left(mol\right)\)
Theo \(pthh\left(1\right):n_{CaCO_3}=\dfrac{1}{2}n_{HCl\left(1\right)}=\dfrac{1}{2}\cdot0,5=0,25\left(mol\right)\)
\(\Rightarrow m_{CaCO_3}=n\cdot M=0,25\cdot100=25\left(g\right)\)
c) Theo \(pthh\left(1\right):n_{CO_2}=\dfrac{1}{2}n_{HCl\left(1\right)}=\dfrac{1}{2}\cdot0,5=0,25\left(mol\right)\)
\(\Rightarrow V_{CO_2}=n\cdot22,4=0,25\cdot22,4=5,6\left(l\right)\)
d) \(m_{CO_2}=n\cdot M=0,25\cdot44=11\left(g\right)\)
\(m_{HCl\left(dư\right)}=n\cdot M=0,1\cdot36,5=3,65\left(g\right)\)
\(m_{d^2A}=\left(m_{CaCO_3}+m_{d^2HCl}\right)-m_{CO_2}\\ =\left(25+200\right)-11=214\left(g\right)\)
\(\Rightarrow C\%\left(HCl_{dư}\right)=\dfrac{3,65\cdot100}{214}=1,71\%\)
a) \(m_{NaOH}=\dfrac{m_{d^2}\cdot C\%}{100}=\dfrac{200\cdot15}{100}=30\left(g\right)\)
\(m_{d^2A\text{ sau khi pha thêm }100\left(g\right)nước}=100+200=300\left(g\right)\)
\(\Rightarrow C\%\left(NaOH\right)=\dfrac{m_{NaOH}\cdot100}{m_{d^2}}=\dfrac{30\cdot100}{300}=10\%\)
b) \(m_{NaOH\text{ sau khi cho thêm }5\left(g\right)NaOH}=30+5=35\left(g\right)\)
\(m_{d^2B}=5+200=205\left(g\right)\)
\(\Rightarrow C\%\left(NaOH\right)=\dfrac{m_{NaOH}\cdot100}{m_{d^2}}=\dfrac{35\cdot100}{205}=17,07\%\)
c) \(C\%\left(NaOH\right)=\dfrac{30\cdot100}{150}=20\%\)
`1)PTHH:`
`NaOH + HNO_3 -> NaNO_3 + H_2 O`
`0,05` `0,05` `0,05` `(mol)`
`n_[NaOH]=[4/100 .50]/40=0,05(mol)`
`n_[HNO_3]=[[12,6]/100 .50]/63=0,1(mol)`
Ta có:`[0,05]/1 < [0,1]/1`
`=>HNO_3` dư
`m_\text{dd sau p/ư}=50+50=100(g)`
`@C%_[NaNO_3]=[0,05.85]/100 .100=4,25%`
`@C%_[HNO_3(dư)]=[(0,1-0,05).63]/100 .100=3,15%`