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\(a.CTHH:K_2CO_3:\\ \%K=\dfrac{78}{138}=56,52\%\\ \%C=\dfrac{12}{138}=8,69\%\\ \%O=100\%-56,52\%-8,69\%=34,79\%\)
\(b.CTHH:H_2SO_4:\\ \%H=\dfrac{2}{98}=2,04\%\\ \%S=\dfrac{32}{98}=32,65\%\\\%O=100\%-2,04\%-32,65\%=65,31\% \)
\(M_{CaCO_3}=40+12+16.3=100\left(\dfrac{g}{mol}\right)\\ \%m_{Ca}=\dfrac{40}{100}.100\%=40\%\\ \%m_C=\dfrac{12}{100}.100\%=12\%\\ \%m_O=100\%-\left(12\%+40\%\right)=48\%\\ M_{Al_2\left(SO_4\right)_3}=27.2+\left(32+16.4\right).3=342\left(\dfrac{g}{mol}\right)\\ \%m_{Al}=\dfrac{2.27}{342}.100\%=15,79\%\\ \%m_S=\dfrac{32.3}{342}.100\%=28\%\\ \%m_O=100\%-\left(28\%+15,79\%\right)=56,21\%\)
a) 3Fe +2 O2 --to--> Fe3O4
b) 4P + 5O2 --to--> 2P2O5
c) Al2O3 + 3H2SO4 --> Al2(SO4)3 + 3H2O
d) Fe2O3 + 3H2SO4 --> Fe2(SO4)3 + 3H2O
e) 2Cu(NO3)2 --to--> 2CuO + 4NO2 + O2
\(a,3Fe+2O_2\xrightarrow{t^o}Fe_3O_4\\ b,4P+5O_2\xrightarrow{t^o}2P_2O_5\\ c,Al_2O_3+3H_2SO_4\to Al_2(SO_4)_3+3H_2O\\ d,Fe_2O_3+3H_2SO_4\to Fe_2(SO_4)_3+3H_2O\\ e,2Cu(NO_3)_2\xrightarrow{t^o}2CuO+4NO_2+O_2\uparrow\)
* Với MgO
- , nMgO = 0,5 (mol) \(\Rightarrow\left\{{}\begin{matrix}n_{Mg}=0,5\left(mol\right)\\n_O=0,5\left(mol\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}m_{Mg}=12\left(g\right)\\m_O=8\left(g\right)\end{matrix}\right.\)
* Với CaCO3
nCaCO3= 0,5 (mol)
\(\left\{{}\begin{matrix}n_{Ca}=0,5\left(mol\right)\\n_C=0,5\left(mol\right)\\n_O=1,5\left(mol\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}m_{Ca}=20\left(g\right)\\m_C=6\left(g\right)\\m_O=1,5.16=24\left(g\right)\end{matrix}\right.\)
* Với H2SO4
nH2SO4 = 0,5 (mol)
\(\Rightarrow\left\{{}\begin{matrix}n_H=1\left(mol\right)\\n_S=0,5\left(mol\right)\\n_O=2\left(mol\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}m_H=1\left(g\right)\\m_S=16\left(g\right)\\m_O=16.2=32\left(g\right)\end{matrix}\right.\)
* Với CuO
nCuO = 0,5 (mol)
=> \(\left\{{}\begin{matrix}n_{Cu}=0,5\left(mol\right)\\n_O=0,5\left(mol\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}m_{Cu}=32\left(g\right)\\m_O=8\left(g\right)\end{matrix}\right.\)
a) CO2 có C = 4; 0 = 2
CH4 có C = 4; H = 1
b) Fe2(S04)3 có Fe = 3; S04 = 2
c); d) tương tự
A)
Gọi công thức dạng chung của hợp chất cần tìm là \(C^{a?}O_2^{II}\)
Theo quy tắc hóa trị, ta có:
a.1=II.2
=>\(a=\frac{2.II}{1}=IV\)
Vậy: Trong CTHH CO2 thì C có họa trị bốn (IV) và O có hóa trị hai (II)
a) Đặt n CaCO3 =1 ( mol )
=> \(\left\{{}\begin{matrix}n_{Ca}=1\left(mol\right)\\n_C=1\left(mol\right)\\n_O=3\left(mol\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}m_{Ca}=40\left(g\right)\\m_C=12\left(g\right)\\m_O=48\left(g\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}\%m_{Ca}=40\%\\\%m_C=12\%\\\%m_O=48\%\end{matrix}\right.\)
b) Đặt n H2SO4 = 1 ( mol )
\(\Rightarrow\left\{{}\begin{matrix}n_H=2\left(mol\right)\\n_S=1\left(mol\right)\\n_O=4\left(mol\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}m_H=2\left(g\right)\\m_S=32\left(g\right)\\m_O=64\left(g\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}\%m_H=2,04\%\\\%m_S=32,65\%\\\%m_O=65,31\%\end{matrix}\right.\)
c) Đặt n Al2S3 = 1 ( mol )
\(\Rightarrow\left\{{}\begin{matrix}n_{Al}=2\left(mol\right)\\n_S=3\left(mol\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}m_{Al}=54\left(g\right)\\m_S=96\left(g\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}\%m_{Al}=36\%\\\%m_S=64\%\end{matrix}\right.\)
d) Đặt n CuO = 1 ( mol )
\(\Rightarrow\left\{{}\begin{matrix}n_{Cu}=1\left(mol\right)\\n_O=1\left(mol\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}m_{Cu}=64\left(g\right)\\m_O=16\left(g\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}\%m_{Cu}=80\%\\\%m_O=20\%\end{matrix}\right.\)
e) Đặt n Fe2(SO4)3 = 1 ( mol )
\(\Rightarrow\left\{{}\begin{matrix}n_{Fe}=2\left(mol\right)\\n_S=3\left(mol\right)\\n_O=12\left(mol\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}m_{Fe}=112\left(g\right)\\m_S=96\left(g\right)\\m_O=192\left(g\right)\end{matrix}\right.\Rightarrow}\left\{{}\begin{matrix}\%m_{Fe}=28\%\\\%m_S=24\%\\\%m_O=48\%\end{matrix}\right.\)
e) Đặt n Fe2(SO4)3 = 1 ( mol )
\(\Rightarrow\left\{{}\begin{matrix}n_{Fe}=2\left(mol\right)\\n_S=3\left(mol\right)\\n_O=12\left(mol\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}m_{Fe}=112\left(g\right)\\m_S=96\left(g\right)\\m_O=192\left(g\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}\%m_{Fe}=28\%\\\%m_S=24\%\\\%m_O=48\%\end{matrix}\right.\)