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mìn còn câu cúi thoii , mn giúp mìn zới :33
HP
31 tháng 10 2021
Ta có: \(n_{CO_2}=\dfrac{3,36}{22,4}=0,15\left(mol\right)\)
PTHH:
CaCO3 + 2HCl ---> CaCl2 + CO2 + H2O (1)
CaO + 2HCl ---> CaCl2 + H2O
a. Theo PT(1): \(n_{CaCO_3}=n_{CO_2}=0,15\left(mol\right)\)
=> \(m_{CaCO_3}=0,15.100=15\left(g\right)\)
=> \(\%_{m_{CaCO_3}}=\dfrac{15}{17,8}.100\%=84,27\%\%\)
\(\%_{m_{CaO}}=100\%-84,27\%=15,73\%\)
b. Ta có: \(m_{CaO}=17,8-15=2,8\left(g\right)\)
=> \(n_{CaO}=\dfrac{2,8}{56}=0,05\left(mol\right)\)
Theo PT(1): \(n_{HCl}=2.n_{CaCO_3}=2.0,15=0,3\left(mol\right)\)
Theo PT(2): \(n_{HCl}=2.n_{CaO}=2.0,05=0,1\left(mol\right)\)
=> \(n_{HCl_{PỨ}}=0,3+0,1=0,4\left(mol\right)\)
Đổi 200ml = 0,2 lít
=> \(C_{M_{HCl}}=\dfrac{0,4}{0,2}=2M\)
LN
0
DT
3
30 tháng 9 2021
Bài 5:
5: Ta có: \(1-\sqrt{x^2-2}=0\)
\(\Leftrightarrow x^2-2=1\)
hay \(x\in\left\{\sqrt{3};-\sqrt{3}\right\}\)
CN
1
W
6 tháng 4 2022
1 She said that she was coming
2 She said that she wouldn't see me the following day
3 She said that he worked in a bank
4 She said that he was living in Paris for a few months
5 Lan said that she would be very busy the next day
6 Thu said that all the students would have a meeting the following sunday
7 Tam said that she could swim acroos that river
8 His sister said that she didn't buy that book
9 The boy said that they had to try their best to win the match
10 Her father said to her that she could go to the movies with her friends
11 Her classmate said that Lan was the most intellligent girl in their class
12 The teacher said that the sun rised in the east
a: \(A=\dfrac{x^2-3+x+3}{\left(x-3\right)\left(x+3\right)}\cdot\dfrac{x+3}{x}=\dfrac{x\left(x+1\right)}{x\left(x-3\right)}=\dfrac{x+1}{x-3}\)
b: |A|=3
=>A=-3 hoặc A=3
=>x+1=3x-9 hoặc x+1=-3x+9
=>-2x=-10 hoặc 4x=8
=>x=2(nhận) hoặc x=5(nhận)