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Solutions *
part 2
Question | Answer |
---|---|
factors that affect solubility | properties of solute, properties of solvent, T, P, |
What is the primarily attractive force between gas molecules and solvent? | dispersion force |
when does dispersion force increase? | with increasing size and mass of molecules |
solubility of gas molecules increase with what? | increasing mass of gas molecules |
higher than normal solubilities of gases are an indication of what? | that a chemical reaction is occuring |
interaction between polar solutes are what kind of force? | dipole-dipole (or hydrogen bonds) |
miscible | liquid that mix |
immiscible | liquids that do not mix |
is ethanol miscible in water? | yes, because the attractive force betwn ethanol molecules include hydrogen bonds, like the force betwn. water molecules |
is octane miscible in water? | no, because attractive force betwn. octane molecules include dispersion forces, not hydrogen. |
can carbon group participate in hydrogen bonding? | no, only dispersion force |
true or false: substances with similar IAF tend to be soluble in one another | true |
kinetic energy increases with what? | increasing temperature |
does increasing temperature reduce the solubility of gas molecules in a solvent? | yes, because gas molecules with enough KE can escape from the surface of a liquid. KE increase with increasing T. |
Kinetic Molecular Theory | if we increase T of a gas, then more gas molecules strike the container in a given amount of time |
does increasing the P make gas more soluble? | yes, because higher P result in more collisions of gas molecules, per unit time, with the solvent |
why does increasing T increases the solubility of solid solutes? | increase T means increase KE. KE of of solute molecules favors separation of solute molecules. Increase KE of solvent molecules allows them to separate the solute molecules easier. |
coligative properties | efects upon the physical properties of water. This result when solutes like NaCl is added to water and can decrease water's freezing T, and increase water boiling T. |
what does colligative properties depend upon? | the # of solute particles in a solution |
what are non-volatile ions? Give examples | ions that does not go into the vapor phase. Na+ and Cl- are examples |
Raoult's Law | the vapor P of the solute-containing solution is equal to the vapor pressure of the pure solvent times the mole fraction of the solvent |
ideal solution obeys what law? | Raoult's Law |
does adding solute lower or higher the vapor pressure? | lower |
is boiling point proportional to molality or molarity? | molality, beccause molality gives info. about the # of moles of solute per mole of solvent. BP is proportional to # of solutes particles per mole of solvent molecules. |
does adding a solute lower of raise the melting point of an aqueous solution? | lower |
the freezing poing temperature is proportional to what? | molality |
semi-permeable membranes | membrane of materials (like cellophane and biological membranes) that have tiny pores that are large enough to allow solvent like water to pass across the membrane, but not the passage of larger solute molecules |
osmotic pressure | pressure pi. this pressure offsets the flow of the solvent. this pressure behaves like pressure in the ideal gas equation |
osmotic pressure (pi) =? | molarity*R*T |
isotonic | two solutions with equal osmotic pressures |
hypotonic | if a solution has a lower osmotic pressure than another |
hypertonic | if a solution has a higher osmotic pressure than another |
increase in boiling point = ? | molality of the solute * molal BP elevation constant Kb (unique for each solvent) |
the decrease in freezing poing temperature = ? | molality of the solute * molal freezing point depression constant Kf (unique for each solvent) |
molal concentration | # of moles of solute per kg of solvent |