Bài 1:

a) 2CuFeS₂ + \(\dfrac{13}{2}\)O₂ --t^o--> 2CuO + Fe₂O₃ + 4SO₂

b) \(n_{CuFeS_2}=\dfrac{3,68}{184}=0,02\left(mol\right)\)

\(n_{O_2}=\dfrac{1,68}{22,4}=0,075\left(mol\right)\)

Xét tỉ lệ: \(\dfrac{0,02}{2}< \dfrac{0,075}{\dfrac{13}{2}}\) => CuFeS₂ hết, O₂ dư

PTHH: 2CuFeS₂ + \(\dfrac{13}{2}\)O₂ --t^o--> 2CuO + Fe₂O₃ + 4SO₂

              0,02----->0,065------->0,02---->0,01---->0,04

=> \(\left\{{}\begin{matrix}n_{O_2\left(dư\right)}=0,075-0,065=0,01\left(mol\right)\\n_{SO_2}=0,04\left(mol\right)\end{matrix}\right.\)

=> \(\left\{{}\begin{matrix}\%V_{O_2}=\dfrac{0,01}{0,01+0,04}.100\%=20\%\\\%V_{SO_2}=\dfrac{0,04}{0,01+0,04}.100\%=80\%\end{matrix}\right.\)

- \(\left\{{}\begin{matrix}m_{CuO}=0,02.80=1,6\left(g\right)\\m_{Fe_2O_3}=0,01.160=1,6\left(g\right)\end{matrix}\right.\)

=> m_rắn = 1,6 + 1,6 = 3,2 (g)

Bài 2: 

a) 

2CuS + 3O₂ --t^o--> 2CuO + 2SO₂

4FeS + 7O₂ --t^o--> 2Fe₂O₃ + 4SO₂

b) Gọi số mol CuS, FeS là a, b (mol)

=> 96a + 88b = 22,8 (1)

\(n_{SO_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\)

=> a + b = 0,25 (2)

(1)(2) => a = 0,1; b = 0,15

=> \(\left\{{}\begin{matrix}n_{CuO}=0,1\left(mol\right)\\n_{Fe_2O_3}=0,075\left(mol\right)\end{matrix}\right.\)

=> \(\left\{{}\begin{matrix}\%m_{CuO}=\dfrac{0,1.80}{0,1.80+0,075.160}.100\%=40\%\\\%m_{Fe_2O_3}=\dfrac{0,075.160}{0,1.80+0,075.160}.100\%=60\%\end{matrix}\right.\)

\(n_S=\dfrac{3.2}{32}=0.1\left(mol\right)\)

\(n_{O_2}=\dfrac{1.12}{22.4}=0.05\left(mol\right)\)

\(S+O_2\underrightarrow{t^0}SO_2\)

\(0.05.0.05...0.05\)

\(\Rightarrow Sdư\)

\(V_{SO_2}=0.05\cdot22.4=1.12\left(l\right)\)

\(b.\)

\(S+O_2\underrightarrow{t^0}SO_2\)

\(0.1..0.1\)

\(V_{kk}=5V_{O_2}=5\cdot0.1\cdot22.4=11.2\left(l\right)\)

a, PT: \(S+O_2\underrightarrow{t^o}SO_2\)

Ta có: \(n_S=\dfrac{3,2}{32}=0,1\left(mol\right)\)

\(n_{O_2}=\dfrac{1,12}{22,4}=0,05\left(mol\right)\)

Xét tỉ lệ: \(\dfrac{0,1}{1}>\dfrac{0,05}{1}\), ta được S dư.

Theo PT: \(n_{SO_2}=n_{O_2}=0,05\left(mol\right)\) \(\Rightarrow V_{SO_2}=0,05.22,4=1,12\left(l\right)\)

b, Theo PT: \(n_{O_2}=n_S=0,1\left(mol\right)\)

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

\(\Rightarrow V_{kk}=2,24.5=11,2\left(l\right)\)

a, Theo giả thiết ta có: \(n_P=\dfrac{3,1}{31}=0,1\left(mol\right)\)

\(4P+5O_2--t^o->2P_2O_5\)

Ta có: \(n_{O_2}=\dfrac{5}{4}.n_P=0,125\left(mol\right)\Rightarrow V_{O_2\left(đktc\right)}=0,125.22,4=2,8\left(l\right)\)

b, Theo giả thiết ta có: \(n_{CH_4}=\dfrac{1,12}{22,4}=0,05\left(mol\right)\)

\(CH_4+2O_2--t^o->CO_2+2H_2O\)

Ta có: \(n_{O_2}=2.n_{CH_4}=0,1\left(mol\right)\Rightarrow V_{O_2\left(đktc\right)}=2,24\left(l\right)\)

\(n_{C_2H_2}=\dfrac{2,8}{22,4}=0,125\left(mol\right)\\ a,2C_2H_2+5O_2\rightarrow\left(t^o\right)4CO_2+2H_2O\\ b,n_{CO_2}=0,125.2=0,25\left(mol\right)\\ m_{CO_2}=0,25.44=11\left(g\right)\\ c,n_{O_2}=\dfrac{5}{2}.0,125=0,3125\left(mol\right)\\ V_{O_2\left(đktc\right)}=0,3125.22,4=7\left(l\right)\\ \Rightarrow V_{kk\left(đktc\right)}=\dfrac{100}{20}.7=35\left(l\right)\)

a)

$4FeS_2 + 11O_2 \xrightarrow{t^o} 2Fe_2O_3 + 8SO_2$
b)

$n_{SO_2} = \dfrac{8,96}{22,4} = 0,4(mol)$
Theo PTHH : 

$n_{FeS_2} = \dfrac{1}{2}n_{SO_2} = 0,2(mol)$
$m = 0,2.120 = 24(gam)$

a,\(n_{SO_2}=\dfrac{8,96}{22,4}=0,4\left(mol\right)\)

PTHH: FeS₂ + O₂ → Fe₂O₃ + SO₂

Mol:     0,4                                      0,4

\(m_{FeS_2}=0,4.120=48\left(g\right)\)

Đáp án D

• hhX gồm n_{CnH2n + 2} = 1,68 : 22,4 = 0,075 mol; 

Đốt cháy 0,075 mol C_nH_{2n + 2}; 0,05 mol C_mH_2m+2–2a → 0,225 mol CO₂

Số C trung bình = 0,225 : 0,125 ≈ 1,8 → Ankan là CH₄.

Ta có: n_CO2 = 0,075 + 0,05m = 0,225 → m = 3

Nhận thấy n_Br2 pứ = 2n_CmH2m+2–2a ⇒ C_xH_y còn lại có a = 2 Û C_mH_2m–2

Û C₃H₄

\(n_S=\dfrac{m_S}{M_S}=\dfrac{3,2}{32}=0,1mol\)

\(n_{O_2}=\dfrac{V_{O_2}}{22,4}=\dfrac{1,68}{22,4}=0,075mol\)

\(S+O_2\rightarrow\left(t^o\right)SO_2\)

0,1> 0,075                     ( mol )

         0,075    0,075         ( mol )

\(V_{SO_2}=V_{O_2}=1,68l\)

nS = 3,2:32=0,1(MOL)
PTHH: S+O2--t->SO2
theo pt , nSO2=nS=0,1(mol)
=> mSO2 = n.M=0,1. (32+16.2)=6,4 (g)

= 1, 68\(l\)