\(M_{Fe_2\left(SO_4\right)_3}=400\left(g\text{/}mol\right)\)

\(\%Fe=\dfrac{56\cdot2}{400}\cdot100\%=28\%\)

\(\%S=\dfrac{32\cdot3}{400}\cdot100\%=24\%\)

\(\%O=100-28-24=48\%\)

\(\%m_O=\dfrac{16.12}{400}.100\%=48\%\)

M_Fe2(SO4)3 = 56 x 2 + 32 x 3 + 16 x 12 = 400 (g/mol)

=> %Fe=56.2400.100%=28%%Fe=56.2400.100%=28%

 

Câu a.

\(M_{Ca\left(NO_3\right)_2}=164\)g/mol

\(m_{Ca\left(NO_3\right)_2}=0,3\cdot164=49,2g\)

\(\%Ca=\dfrac{40}{164}\cdot100\%=24,39\%\)

\(m_{Ca}=\%Ca\cdot49,2=12g\)

\(\%N=\dfrac{14\cdot2}{164}\cdot100\%=17,07\%\)

\(m_N=\%N\cdot49,2=8,4g\)

\(m_O=49,2-12-8,4=28,8g\)

Các câu sau em làm tương tự nhé!

a)\(n_{Ca\left(NO_3\right)_2}=0,3mol\)

   \(n_{Ca}=n_{Ca\left(NO_3\right)_2}=0,3mol\)

   \(m_{Ca}=0,3\cdot40=12g\)

   \(n_N=2n_{Ca\left(NO_3\right)_2}=2\cdot0,3=0,6mol\)

   \(m_N=0,6\cdot14=8,4g\)

   \(n_O=6n_{Ca\left(NO_3\right)_2}=6\cdot0,3=1,8mol\)

   \(m_O=1,8\cdot16=28,8g\)

b)\(n_O=\dfrac{9,6}{16}=0,6mol\)

   Mà \(n_O=12n_{Fe_2\left(SO_4\right)_3}\Rightarrow n_{Fe_2\left(SO_4\right)_3}=\dfrac{0,6}{12}=0,05mol\)

   \(\Rightarrow m=20g\)

c)\(n_{CuSO_4}=\dfrac{3,2}{160}=0,02mol\)

   \(n_O=4n_{CuSO_4}=0,08mol=n_{H_2}\)

   \(V_{H_2}=0,08\cdot22,4=1,792l\)

Tham khảo 

-Ta có:MCu(OH)2=64+16×2+1×2=98g/mol-Trong 1 mol phân tử hợp chất có:1 mol nguyên tử Cu=>Cu=1×64=64g2 mol nguyên tử O=>O=2×16=32g2 mol nguyên tử H=>2×1=2gThành phần % về khối lượng của các nguyên tố:%mCu=(64/98)×100=65,31%%mO=(32/98)×100=32,65%%mH=(2/98)×100=2,04%-Ta có:MFe2(SO4)3=56×2+32×3+16×4×3=400g/mol-Trong 1 mol phân tử hợp chất có:2 mol nguyên tử Fe=>Fe=2×56=112g4 mol nguyên tử S=>S=32×4=128g12 mol nguyên tử O=>O=12×16=192gThành phần % về khối lượng của các nguyên tố:%mFe=(112/400)×100=28%%mS=(128/98)×100=32%%mO=(192/98)×100=48%   

Bài 1: Tính Khối Lượng Của Nguyên Tố Oxi có trong mỗi hợp chất sau:
1. 18 gam nước

\(n_{H_2O}=\dfrac{18}{18}=1\left(mol\right)\Rightarrow n_O=1.1=1\left(mol\right)\)

=> m_O = 1.16 = 16 (g)
2. 2,2 gam CO₂

\(n_{CO_2}=\dfrac{2,2}{44}=0,05\left(mol\right)\Rightarrow n_O=0,05.2=0,1\left(mol\right)\)

m_O = 0,1 .16 =1x6(g)

3. 8 gam CuSO₄

\(n_{CuSO_4}=\dfrac{8}{160}=0,05\left(mol\right)\Rightarrow n_O=0,05.4=0,2\left(mol\right)\)

=> m_O= 0,2.16= 3,2(g)

4. 2 gam Fe₂(SO₄)₃

\(n_{Fe_2\left(SO_4\right)_3}=\dfrac{2}{400}=0,005\left(mol\right)\Rightarrow n_O=0,005.12=0,06\left(mol\right)\)

=> m_O= 0,06.16 = 0,96(g)

a) 

Giả sử có 100 gam hỗn hợp

\(m_O=\dfrac{25.100}{100}=25\left(g\right)\)

=> \(n_O=\dfrac{25}{16}=1,5625\left(mol\right)\)

Mà n_O = 4.n_S

=> \(n_S=\dfrac{1,5625}{4}=\dfrac{25}{64}\left(mol\right)\)

\(\%m_S=\dfrac{\dfrac{25}{64}.32}{100}.100\%=12,5\%\)

b) Đề bài cho rồi mà bn :)

c) 

C1: %m_{kim loại} = \(100\%-12,5\%-25\%=62,5\%\)

=> m_{kim loại} = \(\dfrac{64.62,5}{100}=40\left(g\right)\)

C2:

\(m_S=\dfrac{64.12,5}{100}=8\left(g\right)\)

\(m_O=\dfrac{64.25}{100}=16\left(g\right)\)

=> m_{kim loại} = 64 - 8 - 16 = 40 (g)

\(1,+n_{fe}=\dfrac{5,6}{56}=0,1\left(mol\right)\)

số nguyên tử của Fe là 0,1.6.10\(^{23}\)=0,6.10\(^{23}\)

=> số nguyên tử của Zn là 3.0,6.10\(^{23}\)=1,8.10\(^{23}\)

+ n\(_{zn}\)= \(\dfrac{1,8.10^{23}}{6.10^{23}}\)=0,3 mol 

=> m \(_{Zn}\)=0,3.65=19,5g ( đpcm)

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 )

  \(\Rightarrow\left\{{}\begin{matrix}n_{Fe}=2\left(mol\right)\\n_S=3\left(mol\right)\\n_O=12\left(mol\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}m_{Fe}=112\left(g\right)\\m_S=96\left(g\right)\\m_O=192\left(g\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}\%m_{Fe}=28\%\\\%m_S=24\%\\\%m_O=48\%\end{matrix}\right.\)