I put dihydrogen monoxide (H2O) into plastic containers (of grape juice concentrate) in order to form entry gate columns. I was aware that H2O expands by approximately 9 % when it freezes because as liquid H2O cools below 277 K (4 C), its molecules begin to form a more open, hexagonal crystal structure with more space between them. Accordingly, I left space below plastic container's cover. However, H2O's expansion was directed downwards towards container's bottom for some reason, resulting in unstable situation.
