chem 101! exam 3

polar molecules

molecules with an overall permanent dipole

two factors that cause a molecule to be polar

• differences in electronegativity

• asymmetrical structure (including lone pairs on central atom)

the ___ polar the molecule, the ____ it’s boiling point (bc of ___ dipole-dipole interactions)

more, higher, stronger

hydrogen bonding interaction

an attractive electrostatic dipole-dipole interaction

where can hydrogen bonding interactions occur

• between two separate molecules

or

• between different parts of the same molecule

H-bond donor

H directly bonded to O, N, or F

H-bond acceptor

lone pair on N, O or F (highly electronegative)

ion-dipole interactions

occur when cations and anions interact with molecules that have a permanent dipole

sphere of hydration

multiple layers of water molecules surrounding ions dissolving in water

solution

homogeneous mixture of two or more substances

solvent

component of solution for which the largest number of moles is present (what does the dissolving)

solute

components in a solution other than the solvent (what gets dissolved)

solubility

the maximum quantity of a solute that can dissolve in a given volume of solution

what determines solubility?

strength and number of interactions among solute particles and interactions of solvent molecules

tricks for remembering what’s more soluble

• longer chain = less soluble

• lower charge—>weaker lattice = more soluble

• larger ion—>weaker lattice = more soluble

supercritical fluid

occurs at high temp and pressure, distinct liquid gas phases don’t exist, substance can’t form a solid

what do the different slopes on a phase diagram mean for density?

• positive slope = solid more dense than liquid (sinks)

• negative slope = solid less dense than liquid (floats)

what’s the standard pressure

1 atm

reactants vs products

what’s put into the equation and what comes out

what can you change in a chemical equation

coefficients

combination reaction

when two or more substances react to form one product

decomposition reaction

when one substance breaks down into two or more substances

combustion reaction

rapid reactions that produce a flame

normally a hydrocarbon + oxygen —> co2+o2

stoichiometry

quantitative relationship between substances consumed and produced in a reaction

theoretical yield

the amount of a given product that can be made (the one you calculate)

actual yield

the amount actually produced and measured

percent yield equation

(actual yield / theoretical yield) * 100

ratio of ppm

1 mg of solute/ 1 kg of solvent

or

g/g * 10^6

ratio of ppb

1 µg solute/ 1 kg solvent

or

g/g * 10^9