【Daily Question】Theoretical Foundation 2020.07.16

2020-07-16View Original

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Multiple-choice question: Among the following substances, the order of melting points from low to high should be: A. NH3

Reply #22020-07-16

B, I learned it. I thought silicon dioxide had the highest melting point; it turns out it’s calcium oxide

Reply #32020-07-16

The answer is wrong, I think. Melting point: PH3 (-132.8°C)

Reply #42020-07-16

DSiO2 is an atomic crystal, CaO is an ionic crystal, and NH3 and PH3 are molecular crystals. Generally, atomic crystals have the highest melting points, followed by ionic crystals, with molecular crystals having the lowest melting points. Due to the presence of hydrogen bonds between NH3 molecules, its melting point is higher than that of PH3.

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【Daily Question】Theoretical Foundation 2020.07.16

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