Rationalize why chalk (calcium carbonate) has a higher melting point than motor oil (large compound made from carbon and hydrogen), which has a higher melting point than water and engages in relatively strong hydrogen bonding interactions.

In order to rationalize the differences in melting points, we need to first identify the types of intermolecular forces present in each substance: 1. Chalk (calcium carbonate, CaCO3) is an ionic compound made of calcium ions (Ca2+) and carbonate ions (CO3 2-). Therefore, its main intermolecular force is ionic bonding. 2. Motor oil consists of large carbon and hydrogen-based molecules, which makes it a non-polar substance. Its main intermolecular force is London dispersion forces (Van der Waals forces). 3. Water (H2O) is a polar substance, which means that it has a partial positive charge and a partial negative charge on its molecules. Its main intermolecular force is hydrogen bonding.

Now, we will discuss the different strengths of the intermolecular forces found in each substance: 1. Ionic bonding is the strongest type of intermolecular force. It involves the electrostatic attraction between oppositely charged ions, in this case, Ca2+ and CO3 2-. This strong attraction requires a significant amount of energy to overcome. 2. London dispersion forces are the weakest type of intermolecular force. They are temporary attractions caused by random fluctuations in the electron cloud surrounding a non-polar molecule. These forces are generally weaker in smaller molecules but can become stronger in larger molecules, like those found in the motor oil, due to the increase in surface area for interactions. 3. Hydrogen bonding is a stronger force than London dispersion forces but weaker than ionic bonding. It occurs between molecules when hydrogen is bonded to a highly electronegative atom, such as oxygen, creating a strong dipole-dipole attraction between the partial positive charge on the hydrogen and the partial negative charge on the electronegative atom.

The melting point of a substance is directly related to the strength of its intermolecular forces. A substance with stronger intermolecular forces will require more energy to overcome these forces and, therefore, will have a higher melting point. In our exercise: 1. Chalk has ionic bonding, the strongest intermolecular force, which requires a significant amount of energy to overcome. Thus, chalk has the highest melting point among three substances. 2. Motor oil has London dispersion forces due to its large carbon and hydrogen-based molecules. These forces are stronger than those in small non-polar molecules, so motor oil has a higher melting point than water, which has hydrogen bonding interactions. 3. Water can engage in relatively strong hydrogen bonding interactions compared to London dispersion forces in small molecules. As a result, water has a higher melting point than other substances that rely solely on London dispersion forces, but these forces are not as strong as ionic bonding in chalk, making water's melting point lower than that of chalk. To summarize, chalk has the highest melting point due to strong ionic bonding, motor oil has a higher melting point than water due to its large non-polar molecules and London dispersion forces, and water's melting point is in between because of its relatively strong hydrogen bonding interactions.