3 Ag(s) + 4 HNO3(aq) → 3 AgNO3(aq) + NO(g) + 2 H2O(l) A student investigates the reaction between Ag — Thermodynamics Chemistry Question
Problem Context
3 Ag(s) + 4 HNO3(aq) → 3 AgNO3(aq) + NO(g) + 2 H2O(l)
A student investigates the reaction between Ag(s) and HNO3(aq) represented by the equation above.
Model Answer
The entropy change is positive because the reaction has one mole of gas in the products and none in the reactants.
1 point is earned for the correct answer and a valid justification.
Model Answer
ΔH°rxn = 3(-101) + 90. + 2(-286) − 4(-207) = 43 kJ/molrxn
1 point is earned for the correct calculation of the value of ΔH°rxn.
Model Answer
ΔG° = ΔH° − TΔS°
The reaction is more likely to be favorable at 95°C. At the higher temperature, the term TΔS° is larger and positive; thus, when subtracted from ΔH°, the value of ΔG° is more likely to be negative.
1 point is earned for the correct answer and a valid justification.
Model Answer
The student can evaporate the water, leaving behind solid silver nitrate.
1 point is earned for a valid method.