Question

Which reaction would cause an increase in entropy? A. SO2Cl2(g) SO2(g) + Cl2(g) B. PCl3(g) + Cl2(g) PCl5(g) C. 2CO(g) + O2(g) 2CO2(g) D. C2H2(g) + H2(g) C2H4(g)

Answer 1

A. SO2Cl2(g) --> SO2(g) + Cl2(g) 
1 mole of SOCl2 becomes 1 mole SO2 and 1 mole Cl2 
1 mole --> 2 moles 
entropy increases 

Answer 2

Answer: A) $SO_2Cl_2(g)\rightarrow SO_2(g)+Cl_2(g)$

Explanation: Entropy is the measure of randomness or disorder of a system. If a system moves from an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.

A) $SO_2Cl_2(g)\rightarrow SO_2(g)+Cl_2(g)$

1 mole of gaseous reactant is converting to 2 gaseous products, thus the entropy increases.

B) $PCl_3(g)+Cl_2(g)\rightarrow PCl_5(g)$

2 moles of gaseous reactants are converting to 1 gaseous products, thus the entropy decreases.

C) $2CO(g)+O_2(g)\rightarrow 2CO_2(g)$

3 moles of gaseous reactants are converting to 1 gaseous product, thus the entropy decreases.

D. $C_2H_2(g)+H_2(g)\rightarrow C_2H_4(g)$

2 moles of gaseous reactants are converting to 1 gaseous product, thus the entropy decreases.