a. Ag không phản ứng nên ta có PTHH: \(2Mg+O_2\rightarrow^{t^o}2MgO\)

\(\rightarrow m_{O_2}=m_{hh}-m_{\mu\text{ối}}=18,8-15,6=3,2g\)

\(\rightarrow n_{O_2}=\frac{3,2}{32}=0,1mol\)

b. \(\rightarrow V_{O_2}=n.22,4=22,4.0,1=2,24l\)

\(\rightarrow V_{kk}=4,48.5=11,2l\)

c. Có \(n_{Mg}=2n_{O_2}=0,2l\)

\(\rightarrow m_{Mg}=0,2.24=4,8g\)

\(\rightarrow\%m_{Mg}=\frac{4,8.100}{15,6}\approx30,77\%\)

\(\rightarrow\%m_{Ag}=100\%-30,77\%=69,23\%\)

ko phải e làm đâu nha a , a tham khảo cho 

a)CH4 + 2O2 →→ CO2 + 2H2O (1)

2H2 + O2 →→ 2H2O (2)

b) Đặt nCH4 = a (mol) , nH2 = b (mol)

=> mCH4 = 16a(g) , mH2 = 2b(g)

mà n(CH4 + H2) = V/22,4 = 6,72/22,4 = 0,3(mol)

=> a + b = 0,3(mol) => a = 0,3 - b

Từ PT(1) => nO2 = 2nCH4 = 2a(mol)

Từ PT(2) => nO2 = 1/2 . nH2 = 1/2 . b (mol)

=>tổng nO2 = 2a + 1/2.b (mol)

=> mO2 = n .M = 32. (2a+ 1/2.b )= 64a + 16b(g)

Theo ĐLBTKL:mCH4 + mH2 + mO2 = mCO2 + mH2O(PT1,2)

=> 16a + 2b+ 64a +16b = 11,6

=> 80a + 18b = 11,6

=> 80. (0,3 - b ) + 18b = 11,6

=> b = 0,2(mol)

=> a = 0,3 - 0,2 = 0,1(mol)

=>mCH4 = 16a = 16. 0,1 = 1,6(g) , mH2 = 2b = 2 . 0,2 = 0,4(g)

=> VCH4 = n .22,4 = 0,1 . 22,4 =2,24(l)

VH2 = n . 22,4 = 0,2 . 22,4 = 4,48(l)

tự tính ... 

c) nO2 = 2a + 1/2 .b = 2 . 0,1 + 1/2 . 0,2 = 0,3(mol)

=> VO2 = 0,3 . 22,4 =6,72(l)

mà VO2 = 20% Vkk

=> Vkk = 6,72 : 20% =33,6(l)

PTHH: 

C2H4 + 3O2 -> (t°) 2CO2 + 2H2O

Theo pt: nC2H4 = 1/2 nCO2

=> VC2H4 = 1/2 VCO2 = 1/2 . 44,8 = 22,4 (ml)

%VC2H4 = 22,4/28 = 80%

%VH2 = 100% - 80% = 20%

a, PT: \(CH_4+2O_2\underrightarrow{t^o}CO_2+2H_2O\)

\(2H_2+O_2\underrightarrow{t^o}2H_2O\)

Ta có: \(n_{CH_4}+n_{H_2}=\dfrac{11,2}{22,4}=0,5\left(mol\right)\left(1\right)\)

Theo PT: \(n_{H_2O}=2n_{CH_4}+n_{H_2}=\dfrac{16,2}{18}=0,9\left(mol\right)\left(2\right)\)

Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}n_{CH_4}=0,4\left(mol\right)\\n_{H_2}=0,1\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}\%V_{CH_4}=\dfrac{0,4.22,4}{11,2}.100\%=80\%\\\%V_{H_2}=20\%\end{matrix}\right.\)

b, Theo PT: \(n_{CO_2}=n_{CH_4}=0,4\left(mol\right)\Rightarrow V_{CO_2}=0,4.22,4=8,96\left(l\right)\)

a, \(C_2H_4+Br_2\rightarrow C_2H_4Br_2\)

b, \(n_{Br_2}=\dfrac{19}{160}=0,11875\left(mol\right)\)

\(n_{C_2H_4}=n_{Br_2}=0,11875\left(mol\right)\)

\(\Rightarrow\%V_{C_2H_4}=\dfrac{0,11875.22,4}{5,6}.100\%=47,5\%\)

\(\%V_{CH_4}=100-47,5=52,5\%\)

a)

$CH_4 + 2O_2 \xrightarrow{t^o} CO_2 + 2H_2O$
$C_2H_4 + 3O_2 \xrightarrow{t^o} 2CO_2 + 2H_2O$

$CO_2 + Ba(OH)_2 \to BaCO_3 + H_2O$

b)

Gọi $n_{CH_4} = a(mol) ; n_{C_2H_4} = b(mol)$
$\Rightarorw a + b = \dfrac{1,68}{22,4} = 0,075(1)$

Theo PTHH : $n_{BaCO_3} = n_{CO_2} = a + 2b = \dfrac{19,7}{197} = 0,1(2)$
Từ (1)(2) suy ra : a = 0,05 ; b = 0,025

$\%V_{CH_4} = \dfrac{0,05}{0,075}.100\% = 66,67\%$

$\%V_{C_2H_4} = 100\% - 66,67\% = 33,33\%$

c) $n_{O_2} = 2n_{CH_4} + 3n_{C_2H_4} = 0,175(mol)$
$\Rightarrow V_{O_2} = 0,175.22,4 = 3,92(lít)$
$\Rightarrow V_{kk} = 5V_{O_2} = 19,6(lít)$

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