A certain reaction has ΔH∘=35.4kJ and ΔS∘=85.0J/K. You may want to reference (Pages 831 - 832) Section 19.6 while completing this problem. Part APart complete Is the reaction exothermic or endothermic? exothermic endothermic Previous Answers Correct A positive enthalpy value indicates that energy is absorbed by the system. Therefore, the reaction is endothermic. Part BPart complete Does the reaction lead to an increase or decrease in the disorder of the system? increase decrease Previous Answers Correct The sign of the entropy change is positive, which indicates that the disorder, or entropy, of the system has increased. Part C Calculate ΔG∘ for the reaction at 298 K.

The change in Gibb's free energy, ΔG° for the reaction at 298 K is; 10.070 kJ

Given; we have;

We can evaluate ΔG° by using the formula below;

in which case;

Therefore,

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ΔG° for the reaction at 298 K is 10.070 kJ

Explanation:

Here we have ΔH° = 35.4 kJ

ΔS° = 85.0 J/K

The formula for ΔG° for the reaction is given by the following relation;

ΔG°  = ΔH° - T×ΔS°

Where:

ΔH° = Change in enthalpy of the chemical reaction

ΔS° = Change in entropy of the system and

ΔG° = Change in Gibbs free energy

T  = Temperature of reaction = 298 K

Therefore, ΔG°  = 35.4 kJ - 298 K × 85.0 J/K = 35.4 kJ - 298 K × 85.0 J/K

= 35.4 kJ - 25330 J = 35.4 kJ - 25.330 kJ = 10.070 kJ

Therefore, ΔG° for the reaction at 298 K = 10.070 kJ.

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."