Consider the reactions: (a) 6 CO 2 (g) + 6H 2 O(l) → C 6 H 12 O 6 (aq) + 6O 2 (g) (b) O 3 (g) + H 2 O 2 (l) → 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) → C 6 H 12 O 6 (aq) + 6H 2 O(l) + 6O 2 (g) (b) O 3 (g) + H 2 O 2 (l) → H 2 O(l) + 2O 2 (g) + O 2 (g) Also suggest a technique to investigate the path of the above (a) and (b) redox reactions.

Question

Philoid · Accepted Answer

(a) The process of photosynthesis involves two steps

Step 1:

H₂O decomposes to give H₂ and O₂.

2 H₂O_(l)→ 2H_2(g) + O_2(g)

Step 2:

The H₂ produced in step 1 reduces CO₂, thereby producing glucose (C₆ H₁₂ O₆) and H₂O.

6CO₂(g) + 12H₂(g) → C₆ H₁₂ O₆(aq) + 6H₂O(l)

Now, the net reaction of the process is given as:

It is more appropriate to write the reaction as given above because water molecules are also produced in the process of photosynthesis.

The path of this reaction can be investigated by using radioactive H₂O¹⁸ in place of H₂O.

(b) O₂ is produced from each of the two reactants O₃ and H₂O₂. For this reason, O₂ is written twice.

The given reaction involves two steps. First, O₃ decomposes to form O₂ and O. In the second step, H₂O₂ reacts with the O produced in the first step, thereby producing H₂Oand O_2.

The path of this reaction can be investigated by using H₂O₂¹⁸ or O₃¹⁸.