Chapter 10, Problem 10.51PAE

Through photosynthesis, plants build molecules of sugar containing several carbon atoms from carbon dioxide. In the process, entropy is decreased. The reaction of CO₂with formic acid to form oxalic acid provides a simple example of a reaction in which the number of carbon atoms in a compound increases:

   ${\text{CO}}_{\text{2}}\text{(aq)}+\text{HCOOH(aq)}\to {\text{H}}_{\text{2}}{\text{C}}_{\text{2}}{\text{O}}_{\text{4}}\text{(aq)}$

(a) Calculate the standard entropy change for this reaction and discuss the sign of $\Delta \text{S}°$ .

(b) How do plants carry out reactions that increase the number of carbon atoms in a sugar, given the changes in entropy for reactions like this?