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18

The answer is NO. The article you quote makes a completely unwarranted generalisation that "all flames are hollow". This is true of some flames but only because the fuel that is burning is only able to burn when mixed with oxygen from the air. In those flames, the flame is "hollow" because only in regions where air can mix with the fuel ...

3

Yes, it is possible to fully decompose cinnabar to elemental mercury and sulfur. What conditions need to be satisfied in the new method? Before reaching to decomposition temperature, cinnabar phase transitions to a different polymorph. Data from this paper1 indicate that α-HgS (trigonal) → β-HgS (cubic) phase transition occurs at 673 K and is completed at ...

1

The relative entropies of two substances at a temperature $T'$ are not determined by their relative heat capacities at $T'$. Rather, $$\text {Absolute entropy at } T' \equiv S(T') =\Delta S_{0 \rightarrow T'}$$ $$= \int_{0}^{T'}\frac{\text{đ}q_{rev}}{T} = \int_{0}^{T'}\frac{C_p(T)}{T} dT.$$ I.e., for each substance, you need to consider how $C_p(T)$ varies ...

1

You're not really wrong: the computer program is apparently expecting a float and not an integer, which is really stupid because the question is about temperature change and not the vagaries of significant figures. Instead of you learning about heat capacity and the relation to temperature change, you're instead learning about significant figures first, and ...

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