www.saplinglearning.co/X Ginstant Heat Packs And i × learning.com/ibiscms/mod/ib

Question

www.saplinglearning.co/X Ginstant Heat Packs And i × learning.com/ibiscms/mod/ibis/view.php?id 4220143 ing Jump to... Question 7 of 10 Map Sapling Lean enthalpy of solution, Instant heat packs and cold packs use compounds that have a negative or positive Hu to produce a temperature change. The packs consist of a pouch of water and a dry chemical, MgSO, for heat packs, or NH NO, for cold packs. The pack is activated by breaking the seal of the water pouch, which dissolves the dry chemical and forms a solution that oither increases or decreases in temperature. Predict the signs oard and .. for the following solutions. about us careers privacy policy terms of usecontact us help rch

Explanation / Answer

Ans. #1. NH4NO3, when dissolved in water, absorbs heat from surrounding causing drop in temperature of surrounding (say, the skin on which cold pack is applied).

So, dH > 0, because the solution (NH4NO3- H2O system) absorbs heat from surrounding.

During solvation, the solid NH4NO3 dissociates into NH4+(aq) and NO3-(aq). Formation of more number of products as well conversion of a solid into ions (here, in solvated form) increases the entropy of the system. So, dS > 0.

Thus,

            dH > 0           (endothermic)

            dS > 0            (entropy increases)

#2. Solvation of MgSO4 produces/ releases heat to the surrounding.

So, dH < 0

# Entropy of the system increases because a solid form (MgSO4) is being solvated as well as a molecule dissociates into two ions. So, dS > 0.

Thus,

            dH < 0           (exothermic)

            dS > 0            (entropy increases)

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.