Question

Polychlorinated biphenyls (PCBs), which were formerly used in the manufacture of electrical transformers, are environmental and health hazards. They break down very slowly in the environment. The decomposition of PCBs can be represented by the equation 2 C 12 H 4 Cl 6 + 23 O 2 + 2 H 2 O ⟶ 24 CO 2 + 12 HCl

How many moles of water are needed to react with 10.0 mol O 2 ? moles of water:

mol How many grams of HCl are produced when 15.2 mol H 2 O reacts? HCl produced: g

How many moles of CO 2 are produced when 76.5 g HCl is produced? CO 2 produced: mol

How many grams of C 12 H 4 Cl 6 are reacted when 100.25 g CO 2 is produced? C 12 H 4 Cl 6 reacted: g

How many grams of HCl are produced when 2.5 kg C 12 H 4 Cl 6 reacts? HCl produced: g

Answer 1

2C₁₂H₄Cl₆ + 23O₂ + 2H₂O ----> 24CO₂ + 12HCl

(1) Moles of water :- 10.0 ml

According to equation:-
n(H₂O) = n(C₁₂H₄Cl₆) = 10.0 mol
Answer: n(H₂O) = 10.0 mol

(2) HCL PRODUCED :- 3328.8g

As given in equation the amount of HCl is :-
n(HCl) = 6 x n(H2O)

= 6 x 15.2

n(HCL)= 91.2 mol

The mass of HCl is :-
m(HCl) = n(HCl) x MW(HCl)

= 91.2 x ( 1+ 35.5)

= 3328.8 g
(3) Moles of CO₂ = 4.20 mol

n(HCl) = m(HCl) / MW(HCl)

= 76.5 / 36.5

n(HCL)= 2.10 mol

According to equation :-
n(CO₂) = 2n(HCl)

= 2 x 2.10

= 4.20 mol
(4) PCB/ C₁₂H₄ Cl₆ formed = 68.59g

MW(PCB) = 12 x 12 + 4 x 1 + 6 x 35.5

= 361 g/mol
n(CO₂) = m(CO₂) / MW(CO₂)

= 100.25 / 44

= 2.28 mol
According to equation
n(C₁₂H₄ Cl₆) = n(CO₂) / 12

= 2.28 /12

= 0.19 mol
m(C₁₂H₄ Cl₆) = n(C₁₂H₄ Cl₆) x MW(C₁₂H₄ Cl₆)

= 0.19 x 361

= 68.59 g

(5) HCL PRODUCED = 1517.7 g

n(C₁₂H₄ Cl₆) = m(C₁₂H₄ Cl₆) / MW(C₁₂H₄ Cl₆)

= 2500 / 361

= 6.93 mol
According to equation
n(HCl) = 6n(C₁₂H₄Cl₆)

= 6 x 6.93

= 41.58 mol
m(HCl) = n(HCl) x MW(HCl)

= 41.68 x 36.5

= 1517.7 g