Hybridization & bonding
What type of overlap forms a sigma bond?
end to end overlap of orbitals
what two conditions are required for hydrogen bonding?
2. a nearby lone pair on N, O, or F
what does "like dissolves like" mean?
polar dissolves polar; non polar dissolves non polar.
is evaporation endothermic or exothermic and why?
Endothermic
Define molarity
mol solute/L solution
what hybridization corresponds to trigonal planar geometry?
sp2
Why does I2 have a higher boiling point than Br2
higher molecular weight and increased London dispersion due to size.
how does gas solubility change as temperature increases?
gas solubility decreases as temperature increases.
What must occur for a liquid to boil?
vapor pressure = external pressure
Define molality, and define mole fraction
m=mol solute/kg solvent
mole fraction = mol solute/ total moles in solution.
What type of orbitals combine to form a pi bond?
side to side overlap of unhybridized p orbitals
what is the weakest intermolecular force?
London dispersion forces
Why is it important to cool down power plant water before returning it to lakes?
hot water reduces oxygen levels which kills the fish.
why is ice less dense than water and why is this important?
hydrogen bonding forces water into an open hexagonal structure when solid. Because ice floats, ecosystems don't get killed in winter (lakes).
Define percent, ppm, and ppb
x100
x1,000,000
x109
hybridization of lower oxygen in HCO2-
sp2
Clearly state the difference between dipole-dipole forces and London dispersion.
Dipole–dipole = attraction between permanent dipoles (polar molecules).
LDF = temporary dipoles → universal, weakest, stronger in big atoms.
What structure feature determines if a pesticide is water soluble or fat soluble?
Many polar groups, (O, N) = water soluble
long hydrocarbon chains = fat soluble.
why does wind feel colder after a snow storm?
evaporation of snow pulls heat form skin. (endothermic)
A solution is 25 % H2o2 by mass, what volume of hydrogen peroxide is in a 100g solution. assuming density = 1.1g/mL
22.7mL
describe the hybridization of HCN. include information of each atom and number of different types of bonds.
C= sp
N=sp
total of 2 sigma bonds and 2 pi bonds
Why does water boil at a lower temperature at high altitude?
atmospheric pressure is lower and therefore the water molecules need less energy to phase change.
according to Henry's law, what two factors determine gas solubility?
1. Henry's constant kH
2. gas partial pressure
Sgas=kHPgas
Draw the phase change energy diagram of H2O.
ice, melting, liquid water, evaporation, water vapor
A 100g solution with water is 25% H₂O₂ by mass. H₂O₂ has a density of 1.1g/ml
What is the molarity of the solution?
Assume that the volumes of the components are additive when mixed.
7.52 mol/L