Chemistry - Thermochemistry Question with Solution | TestHub
In an ice calorimeter, a chemical reaction is allowed to occur in thermal contact with an ice-water mixture at 0°C. Any heat liberated by the reaction is used to melt some ice; the volume change of the ice-water mixture indicates the amount of melting. When solutions containing 1.0 millimole each of AgNO3 and NaCl were mixed in such a calorimeter, both solutions having been pre-cooled to 0°C, 0.20 g of ice melted. Assuming complete reaction in this experiment, what is ΔH for the reaction: Ag+(aq) + Cl-(aq) → AgCl(s)? Latent heat of fusion of ice at 0°C is 80 cal/g.
Options:
Answer:
Solution:
The heat released is calculated as 0.20 g × 80 cal/g = 16 cal for 1.0 millimole of reaction.
To find the heat released per mole, we multiply by 1000:
16 cal × 1000 = 16000 cal = 16 kcal.
Since heat is liberated, the change in enthalpy (Δ H) is negative.
Therefore, Δ H = -16 kcal/mol. This corresponds to option (a).
