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Consider the reaction 6CO2(g) + 6H2O(l) ----C6H12O6(aq)+ 6O2(g)

 8.9 Consider the reactions:
(a) 6CO_{2}_{(g)}+6H_{2}O_{(l)}\rightarrow C_{6}H_{12}O_{6}_{(aq)}+6CO_{2}_{(g)}

(b) O_{3}_{(g)}+H_{2}O_{2}_{(l)}\rightarrow H_{2}O(l) +2O_{2}(g)
Why it is more appropriate to write these reactions as :

(a) 6CO_{2}_{(g)}+12H_{2}O_{(l)}\rightarrow C_{6}H_{12}O_{6}_{(aq)}+6H_{2}O_{(l)}+6CO_{2}_{(g)} 

(b) O_{3}_{(g)}+H_{2}O_{2}_{(l)}\rightarrow H_{2}O(l) +O_{2}(g)+O_{2}_{(g)}

 Also, suggest a technique to investigate the path of the above (a) and (b) redox reactions. 

Answers (1)
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Answer-

(a) In the photosynthesis process-

step 1- the    liberation of  O_{2} and  H_{2}  -->        2H_{2}O\rightarrow O_{2}+2H_{2}

step-2 The H_{2} produced in above reduces the CO_{2} into glucose(C_{6}H_{12}O_{6}) and water(H_{2}O)

                  6CO_{2}+12H_{2}\rightarrow C_{6}H_{12}O_{6}+6H_{2}O

So, the final net reaction is  

2H_{2}O\rightarrow CO_{2}+2H_{2}]*6\\+6CO_{2}+12H_{2}\rightarrow C_{6}H_{12}O_{6}+6H_{2}O\\------------------\\6CO_{2}+12H_{2}O\rightarrow C_{6}H_{12}O_{6}+6H_{2}O

It is more appropriate to write the reaction as above because water(H_{2}O) molecule also produced in photosynthesis reaction. 

The path of reaction can be investigated by using the radioactive H_{2}O^{18} instead of  (H_{2}O) 

 

(b)

 \\O_{3}(g)\rightarrow O_{2}(g)+O(g)\\ H_{2}O_{2}(l)+O(g)\rightarrow H_{2}O(l)+O_{2}(g)\\ ---------------\\ H_{2}O_{2}(l)+O_{3}(g)\rightarrow H_{2}O(l)+O_{2}(g)+O_{2}(g) (the final net reaction)

Dioxygen is produced from both steps, one from the decomposition of ozone (O_{3}) and other is from the reaction of hydrogen peroxide with(O)

  • The path of the reaction can be investigated by using O^{18}_{3}/ H_{2}O^{18}.
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