A solid compound in a sealed container was kept at a very low temperature in a freezer. When placed at room temperature, the substance quickly turned into a liquid. This compound is most likely which of the following?
A. an ionic compound because it has a low boiling point
B. a covalent compound because it has a low boiling point
C. an ionic compound because it has a low melting point
D. a covalent compound because it has a low melting point
Answer (3)
Since this process involves a matter-state change from solid to liquid, melting is occurring.
Ionic compounds have very strong intermolecular 'bonds': this is because it is formed by a metal atom donating one or more electrons to a non-metal atom in order to result in complete valence shells, with the effect that opposite ions are formed (opposites attract). Hence a large input of energy is needed to overcome these 'bonds' and form a liquid from the giant solid ionic lattice - therefore ionic compounds have high melting and boiling points.
Conversely a covalent bond occurs between two non-metal atoms - unlike ionic compounds which form giant ionic structures, covalent bonds are used to form molecules. These only have weak intermolecular forces, which need a small energy input to overcome: therefore the melting and boiling points will be much lower.
Considering that the compound has been taken from the freezer, which is 0 degrees celcius or lower, the state change has occurred at a low temperature. This makes it extremely likely that the compound is covalent.
In conclusion, the correct answer is d .
The question asks which type of compound, a solid kept at very low temperature that quickly turned into a liquid when placed at room temperature, is most likely described. The correct option is d. a covalent compound because it has a low melting point.
Compounds containing covalent bonds generally have lower melting and boiling points than those containing ionic bonds. This is because the energy needed to disrupt the relatively weaker intermolecular forces in covalent compounds is less than the energy required to break the stronger ionic bonds in ionic compounds. Since the compound in question quickly turned into a liquid at room temperature, it suggests that it has a low melting point, typical of covalent compounds, rather than an ionic compound which usually has a higher melting point.
The correct answer is D: a covalent compound because it has a low melting point. This is because ionic compounds typically have high melting points, while covalent compounds generally have lower melting points, causing them to melt quickly at room temperature. Therefore, the scenario described fits best with a covalent nature of the compound.
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