The chemical reaction that causes chromium to corrode in air is given by 4Cr+3O2→2Cr2O3 in which at 298 K ΔH∘rxn = −2256 kJ ΔS∘rxn = −549.1 J/K Part A What is the standard Gibbs free energy for this reaction? Assume the commonly used standard reference temperature of 298 K.

The standard gibbs free energy for this reaction is -2092.4 kJ

Explanation:

Step 1: Data given

Temperature = 298 K

ΔH° rxn = −2256 kJ

ΔS° rxn = −549.1 J/K

Step 2: The balanced equation

4Cr + 3O2 → 2Cr2O3

Step 3:

The formula for the gibbs free energy is:

ΔG° = ΔH° - T * ΔS°

⇒with ΔG° = the gibbs free energy for this reaction = TO BE DETERMINED

⇒with ΔH° = the standard enthalpy of the reaction  = −2256 kJ

⇒with T = the temperature of the reaction in Kelvin = 298 K

⇒with ΔS°  = standard entropy of the reaction = −549.1 J/K

ΔG° = -2256 kJ - 298 K* (-0.5491 kJ/K)

ΔG° = -2256 kJ + 163.6318 kJ

ΔG° = -2092.4 kJ

The standard gibbs free energy for this reaction is -2092.4 kJ

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.