Exam 1 Study Guide Flashcards
Dispersion force
all liquids/solids experience; weakest force
- increases w/ increasing molar mass
London force
dispersion force for nonpolar species
dipole-dipole interaction
- polar molecules
- higher melting and boiling points
hydrogen bonding
F-H, N-H, O-H
- highest melting and boiling points
hydrophilic
water-soluble
- ions, polar molecules, H-bonds
hydrophobic
water-insoluble
- hydrocarbons (alkanes)
boiling point increases w/ increasing ___
- increasing molar mass
- increasing polarity
- increases greatly w/ hydrogen bonding
branching disrupts ___
the amount of surface area molecules that interact
- decreases van der Waals interaction–>
- decreases boiling point
dipole-dipole interactions, dipole-induced-dipole interactions, and dipole-induced-dipole-induced interactions occur b/w what molecules?
- dipole-dipole interactions: polar and polar molecule (no H-bonds)
- dipole-induced-dipole interactions: polar and non polar
- dipole-induced-dipole-induced interactions: nonpolar and nonpolar molecules
triple point
- pressure and temperature at which solid, liquid and gas of a pure substance coexist in equilibrium
- the lowest pressure at which the liquid phase can exist
below the triple point…
solid –> vapor or vapor –> solid
critical temperature
lowest temp liquid and gas coexist
melting point: molecular, ionic, metallic, covalent
- molecular: low (lowest)
- ionic: high
- metallic: hard to predict
- covalent: very high (highest)
conductivity: molecular, ionic, metallic, covalent
- molecular: poor conductor
- ionic: poor conductor
- metallic: excellent conductors
- covalent: poor conductor
strength: molecular, ionic, metallic, covalent
- molecular: soft
- ionic: hard but brittle
- metallic: ductile, malleable
- covalent: very hard and very brittle
sheen: molecular, ionic, metallic, covalent
- molecular: dull
- ionic: dull
- metallic: shiny
- covalent: dull
Is rate dependent upon concentration? Why or why not?
yes, as concentration increases, rate increases
What is the significance of k? Is it dependent upon pressure? Temperature?
- k = rate constant
- depends on temp (not pressure)
The half-life of which order reaction (0,1,2 which?) is independent of concentration?
1st
the unit of a rate constant is always
M^-(order-1)*S^(-1)
For which order reaction would reactant A be totally consumed in twice the half-life of the reaction?
0th order
For which order does the concentration of the reactant decrease by 1⁄4 in twice the half-life of the reaction?
1st
define equilibrium
rate forward = rate backwards
- forming reactants at same rate forming products
Is an elementary step the same as an elementary reaction?
yes
What is the rate-limiting step?
- the slowest step
- determines overall rate of reaction
- Rslow = Roverall
what is an intermediate?
produced and consumed but not in overall reaction
- right –> left side (products –> reactants)
t/f: rate law depends on intermediates
FALSE (independent of intermediates, must substitute in rate expressions)
what is a catalyst?
produced and consumed but not in overall reaction
-left –> right side (reactants –> products)
Is concentration of catalyst allowed in a rate law (rate expression)?
it could be used
activation energy
minimum energy to start a reaction
activation energy depends on…
the substance (NOT temp, pressure, or concentration)
how does a catalyst impact activation energy?
decreases
K = ?
= K(forward)/K(backward)
= k1/k-1
= [products]^# / [reactants]^#
formation reaction
forming 1 mole of a compound from the 2 elements in their natural temp and pressure
what does a large K value mean?
mostly product at equilibrium, very little starting material
a small K value means…
mostly starting material, very little product
What quantity represents the extent of reaction?
how much product is made at equilibrium