Organic Chemistry Melting Point Lab

Melting point

temperature at which the solid phase and liquid phase are at equilibrium at a given pressure

factors affecting melting point

bonding and attractive forces, intermolecular forces, size, shape, pressure, and impurity

bonding and attractive force affect on melting point

ionic bonds have higher melting points due to stronger attractions between particles than covalent bonds

intermolecular attractive force affects on melting point

stronger forces like hydrogen bonding have a higher melting point

size affects on melting point

larger molecules have higher melting points due to increased van der Waals forces.

shape affects on melting point

molecules with more symmetry typically have higher melting points due to more efficient packing.

pressure affects on melting point

Increased pressure can increase the melting point by forcing molecules closer together.

what molecule is exempt from the increase pressure equals increased mp

ice

impurity affects on melting point

The presence of impurities typically lowers the melting point of a substance as they disrupt the orderly packing of molecules.

ranges of mp for pure substances

narrow

ranges of mp for impure substances

wide

energy needed to convert solid to liquid

heat of fusion; endothermic

energy needed to convert a solid to a gas

heat of sublimation; endothermic

condensation

reverse of sublimation; -Hsub, exothermic

energy needed to convert a liquid to a gas

heat of vaporization; endothermic

triple point

when both the temperature and pressure of the three phases of the substance coexist in equilibrium

critical point

temperature and pressure at which a substance's liquid and gas phases become indistinguishable