2Zn+O2-to>2ZnO

0,1---0,05----0,1

n Zn=0,1 mol

nO2=0,025 mol

=>VO2=0,05.22,4=1,12l

=>mZnO=0,1.81=8,1g

c)Zn dư

=>m ZnO=0,05.81=4,05g

2Zn+O2-to>2ZnO

0,1---0,05----0,1

n Zn=6,5/65=0,1 mol

n O2=0,8/32=0,025 mol

=>VO2=0,05.22,4=1,12l

=>mZnO=0,1.81=8,1g

c)Zn dư

=>m ZnO=0,05.81=4,05g

.

Chọn B.  

Theo đề ta có:  n O 2 = 1 , 225 ;   n C O 2 = 1 , 05   v à   n H 2 O = 1 , 05 => X no, đơn chức, mạch hở (vì  n C O 2 =   n H 2 O )

Chọn B

SDPU: CH4 + O2--> CO2 + H2O

PTHH: CH4 + 2O2--> CO2 + 2H2O

             1          2          1          2

           0,05     0,1       0,05     0,1

nCH4=V/22,4= 1,12/22,4=0,05mol

VO2=n.22,4=0,1.22,4= 2,24 lít

VCO2=n.22,4=0,05.22,4=1,12 lít

SDPU: CH4 + O2--> CO2 + H2O PTHH: CH4 + 2O2--> CO2 + 2H2O 1 2 1 2 0,05 0,1 0,05 0,1 nCH4=V/22,4= 1,12/22,4=0,05mol VO2=n.22,4=0,1.22,4= 2,24 lít VCO2=n.22,4=0,05.22,4=1,12 lít

\(n_{CH_4}=\dfrac{1,12}{22,4}=0,05\left(mol\right)\)

\(PTHH:CH_4+2O_2->CO_2+2H_2O\)

\(V_{O_2}=0,1.22,4=2,24\left(l\right)\)

\(V_{CO_2}=0,05.22,4=1,12\left(l\right)\)

Đáp án B

Theo giả thiết, bảo toàn nguyên tố C và bảo toàn electron, ta có :

\(a) CH_4 + 2O_2 \xrightarrow{t^o} CO_2 + H_2O\\ 2C_2H_2 + 5O_2 \xrightarrow{t^o} 4CO_2 + 2H_2O\\ b) n_{CH_4} = a(mol) ; n_{C_2H_2} = b(mol)\\ \Rightarrow a + b = \dfrac{6,72}{22,4} = 0,3(1)\\ n_{O_2} = 2a + \dfrac{5}{2}b = \dfrac{22,4}{32} = 0,7(2)\\ (1)(2) \Rightarrow a = 0,1 ; b = 0,2\\ \%V_{CH_4} = \dfrac{0,1.22,4}{6,72}.100\% = 33,33\%\\ \%V_{C_2H_2} = 100\% - 33,33\% = 66,67\%\)

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

\(2C_2H_2+5O_2\underrightarrow{t^o}4CO_2+2H_2O\)

b, Giả sử: \(\left\{{}\begin{matrix}n_{CH_4}=x\left(mol\right)\\n_{C_2H_2}=y\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow x+y=\dfrac{6,72}{22,4}=0,3\left(mol\right)\left(1\right)\)

Ta có: \(n_{O_2}=\dfrac{22,4}{32}=0,7\left(mol\right)\)

Theo PT: \(n_{O_2}=2n_{CH_4}+\dfrac{5}{2}n_{C_2H_2}=2x+\dfrac{5}{2}y\left(mol\right)\)

\(\Rightarrow2x+\dfrac{5}{2}y=0,7\left(2\right)\)

Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}x=0,1\left(mol\right)\\y=0,2\left(mol\right)\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}\%V_{CH_4}=\dfrac{0,1}{0,3}.100\%\approx33,33\%\\\%V_{C_2H_2}\approx66,67\%\end{matrix}\right.\)

Bạn tham khảo nhé!

Bài 1:

a) n_Fe = \(\frac{25,2}{56}= 0,45\) mol

Pt: 3Fe + ..2O₂ --to--> Fe₃O₄

0,45 mol-> 0,3 mol

V_O2 = 0,3 . 22,4 = 6,72 (lít)

b) Pt: CH₄ + ....2O₂ --to--> CO₂ + 2H₂O

......0,15 mol<-0,3 mol

m_CH4 = 0,15 . 16 = 2,4 (g)

Bài 2:

a) n_Al = \(\frac{5,4}{27}= 0,2\) mol

Pt: 4Al + 3O₂ --to--> 2Al₂O₃

0,2 mol->0,15 mol-->0,1 mol

m_Al2O3 = 0,1 . 102 = 10,2 (g)

b) V_O2 = 0,15 . 22,4= 3,36 (lít)

Mà: V_O2 = 20%V_kk = 0,2V_kk

=> V_kk = \(\frac{VO2}{0,2}=\frac{3,36}{0,2}=16,8 \) (lít)

Bài 3:

Ta có: V_O2 = 20%V_kk = 0,2V_kk = 0,2 . 11,2 = 2,24 (lít)

=> n_O2 = \(\frac{2,24}{22,4}=0,1\) mol

Pt: 2Mg + O₂ --to--> 2MgO

0,2 mol<-0,1 mol

m_Mg = 0,2 . 24 = 4,8 (g)

Chúc bn học tốt ^_^

\(n_{Al}=\dfrac{5,4}{27}=0,2\left(mol\right)\\a, PTHH:4Al+3O_2\rightarrow\left(t^o\right)2Al_2O_3\\ b,n_{O_2}=\dfrac{3}{4}.n_{Al}=\dfrac{3.0,2}{4}=0,15\left(mol\right)\\ \Rightarrow V_{O_2\left(đktc\right)}=0,15.22,4=3,36\left(l\right)\\ c,2KMnO_4\rightarrow\left(t^o\right)K_2MnO_4+MnO_2+O_2\\ n_{KMnO_4}=2.n_{O_2}=2.0,15=0,3\left(mol\right)\\ \Rightarrow m_{KMnO_4}=158.0,3=47,4\left(g\right)\)