The fictitious compound PrF₂ has a dissociation equilibrium given by: PrF₂ (s) ⇌ Pr²⁺ (aq) + 2F⁻ (aq). The solubility of PrF₂ in water is 5.5 g/mL at 40°C and 0.88 g/mL at 100°C. Based on these data, the solubility of PrF₂ is an __________ process; dissolution increases at __________ temperatures.
- Exothermic; lower
- Exothermic; higher
- Endothermic; lower
- Endothermic; higher



Answer :

Answer:

- Exothermic; lower

Explanation:

First let's determine whether the dissolution of PrF₂ is endo or exo thermic.

  • At 40 °C the dissolution of PrF₂ is 5.5 g/mL
  • At 100 °C the dissolution of PrF₂ is 0.88 g/mL

This indicates that as temperature increases, the rate of the forward reaction decreases meaning that this reaction is exothermic.

Since the reaction is exothermic and the dissolution value is higher at lower temperatures, the dissolution process occurs at lower termperatures.

Therefore, the correct answer is Exothermic; lower.