Question

To receive credit, you must show your work. STAPLE all pages before submitting your homework. Problems will be selected at random for grading, but a full answer key will be posted to Blackboard 1. solids, liquids, and solutions, and intermolecular forces. 1. For each pair of substances, identify which has the highest melting point. For each, briefly explain your reasoning a. b. c. Ne Be d. e. Surface area also matters. More surface area, more contact, stronger cohesion. Your book mentions this. Based on that, which do you think is most likely to be a solid at room temperature?

1. For each pair of substances, identify which has the highest melting point. For each, briefly explain your reasoning

Answer 1

1.a. Anthracene has the highest melting point as with the increase in molecular weight Vander waals force of attraction increase. Also, Here as we move from benzene to naphthalene to antracene Aromaticity increases as well as aromatic rings increases, this in turn increses the chances of pi-pi stacking which also helps in increasing melting point.

1.b. Water has the highest melting point because it has Maximum hydrogen bonds.. The ability to make H-bonds also increases from N to O to F. Since among these given pairs Water has the maximum H-bond strength, it has Maximum melting point. CH_{​​​​​4} has no H-Bond hence least melting point

1.c. Be has the maximum melting point as it is bounded by metallic forces which arises due to the conduction electrons. This special force makes it a solid where's others have only vander waals force of attraction and hence gas.

1.d. At-At has Maximum melting point as with increase in size and molecular weight vander waals force of attraction increases.

1.e. n-pentane has Maximum melting point as the length of chain increases surface area also increases and hence Vander waals force increases. Branching decreases surface area of the compound.