Question
In a common example of supercooling, putting a bottle in a freezer and then agitating it nucleates the formation of this substance. For 10 points each:
[10e] Name this solid substance that unusually has a higher volume and lower density than its liquid counterpart due to increasing rigidity between its O–H hydrogen bonds.
ANSWER: ice [or water ice; prompt on H2O (“H-2-O”); reject “water”]
[10m] Most instances of ice crystals on Earth exist in the Ih (“eye-H”) form, whose symmetry aligns with this shape. Face-centered cubic lattices and a lattice named for this shape are the only two lattices that are close-packed.
ANSWER: hexagons [accept hexagonal symmetry; accept hexagonal close-packed]
[10h] The space group for hexagonal ice contains one of these symmetry operations consisting of a reflection and parallel translation. Hermann–Mauguin (“mo-GAN”) notation uses a lowercase a, b, or c to represent this symmetry operation.
ANSWER: glide plane [or glide plane symmetry; prompt on transflection]
<Chemistry>
Summary
| 2023 ACF Winter @ Columbia | 11/11/2023 | Y | 9 | 18.89 | 89% | 100% | 0% |
Data
| Cornell C | Princeton B | 10 | 10 | 0 | 20 |
| NYU A | Columbia C | 10 | 10 | 0 | 20 |
| Penn A | Haverford | 10 | 10 | 0 | 20 |
| Rutgers A | NYU B | 10 | 10 | 0 | 20 |
| Yale A | Penn B | 10 | 10 | 0 | 20 |
| Rowan A | Yale B | 10 | 10 | 0 | 20 |
| Vassar | Yale C | 10 | 10 | 0 | 20 |
| Princeton A | Bard A | 0 | 10 | 0 | 10 |
| Columbia A | Rutgers B | 10 | 10 | 0 | 20 |