Dry ice (solid carbon dioxide) sublimates directly into carbon dioxide gas at a constant temperature of −78.5∘C-78.5^\circ\text{C}−78.5∘C. Which statement correctly describes the changes in the average kinetic energy and the potential energy of the carbon dioxide molecules during this transition?
The average kinetic energy of the molecules increases, and their potential energy remains constant.
The average kinetic energy of the molecules remains constant, and their potential energy increases.
The average kinetic energy of the molecules remains constant, and their potential energy decreases.
Both the average kinetic energy and the potential energy of the molecules increase.
Practise OCR GCSE Chemistry The particle model with exam-style questions for Foundation and Higher tier. 41 questions, matched to the OCR GCSE Chemistry (J248) specification and written in Paper 1 and Paper 2 (Foundation Tier) or Paper 3 and Paper 4 (Higher Tier) style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.