Examine able chemistry questions with well explained answers

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• Explain the statement “you need attractive forces to condense and repulsive forces to freeze”. o As mentioned above, the attractive forces actually cause the molecules in a gas to collapse ... to a much denser solid or liquid state. The difference between a solid and a liquid, on the other hand, is that the molecules in a solid are fixed in space whereas those in a liquid can move around. It is the short range repulsions that hold the molecules in place in the solid state, because these are the interactions that represents what happens when two particles come in contact. (To hold something in place, even in common speech, means to put it in contact with enough other objects such that it no longer has any place to move.) • What are dispersion or London forces? Describe how they arise. o Atoms and molecules are tiny highly charged positive centers surrounding by a “cloud” of negative electrons. As the electrons move around the cloud changes shape and “instantaneous” dipoles are created. These dipoles will then induce dipoles in nearby atoms and molecules with the net effect of allowing for a favorable dipole-dipole interaction. We call these forces between fluctuating dipoles dispersion or London forces. • Why are some substances gases at room temperature, but others are liquid or solid? o It depends on their intermolecular forces; the stronger the intermolecular forces, the more likely the substance is going to be a liquid or a solid at room temperature. This is because it will take a stronger energy (heat energy, in our case) to disturb the intermolecular forces in a liquid or solid than it will in a gas, which we assume to [Show More]

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