Forces
Define intermolecular force.
Forces of attraction between molecules
What is viscosity?
What is a crystalline solid?
A solid with particles arranged in an orderly repeating pattern throughout
What two thermodynamic quantities affect whether a solution forms?
Enthalpy and entropy
What pressure of carbon dioxide is needed to maintain a CO2 concentration of 0.10 M in a can of lemon-lime soda?
KH = 3.4 × 10−2 M/atm
2.94 atm
Explain dipole-dipole attractions.
What is surface tension?
The tendency of a liquid to adopt a shape that minimizes its surface area
What is an amorphous solid?
A solid with particles not arranged in an orderly, repeating pattern.
Explain "like dissolves like".
For a solution to form, the solvent-solvent and solute-solute forces must be similar to (and thus replaceable by) the solvent-solute forces - hence, polar solutes dissolve better in polar solvents, and nonpolar solutes dissolve better in nonpolar solvents
What is the boiling point of a solution of 115.0 g of sucrose in 350.0 g of water?
(Sucrose molar mass = 342.3 g/mol, Kb = 0.512 °C/m)
100.5 °C
Explain hydrogen bonding.
H bonded to O, N, or F causes highly concentrated partial charges due to the small size of the atoms and high EN difference - attractions exist between H atom of one molecule and the O/N/F of another
State factors affecting viscosity.
Strength of intermolecular forces in the substance, size and complexity of individual molecules
Why do crystalline solids melt at precise temperatures while amorphous solids melt over a range of temperatures?
Intermolecular forces in a crystal are uniform and all require the same amount of energy to overcome and transition to liquid state; in amorphous solids, the forces are nonuniform and are overcome with varying amounts of kinetic energy
Why is xenon 11 times as soluble as helium in water at a given temperature?
Xenon atoms are much larger than helium atoms, and their greater surface area gives rise to greater dispersion forces in solution
What is the freezing point of a solution of 115.0 g of sucrose in 350.0 g of water?
(Sucrose molar mass = 342.3 g/mol, Kf = 1.86 °C/m)
-1.8 °C
Explain dispersion forces.
Fluctuations in electron density give rise to temporary dipole moments which can induce opposite dipoles in nearby molecules, generating an attractive force
Explain why a meniscus forms when water is placed in a graduated cylinder.
Adhesive forces between the water and the glass cause water to creep up the glass surface
There was supposed to be a picture of a heating curve here with a mistake that you had to point out, but JeopardyLabs wants me to pay for the privilege of uploading an image, so stand by for the workaround
Vaporization transition should require more heat than melting transition
Why does the solublility of any gas in water decrease with increasing temperature?
Increased temperature is increased average kinetic energy of particles, and with greater kinetic energy, gas particles are better able to overcome forces keeping them in solution and escape to the gas phase
What is the osmotic pressure of a solution containing 0.01 mol calcium nitrate in 275 mL of water?
2.67 atm
Arrange the following in order of increasing boiling point:
NH3 H2 CHCl3
H2 , CHCl3 , NH3
Why does a liquid's viscosity decrease with increasing temperature?
Increased temperature is increased average kinetic energy of particles - the greater kinetic energy overcomes the intermolecular forces causing the liquid to resist flow
Solid Kr and solid Cu both consist of individual atoms - why are their properties so different?
Cu, a metal, exhibits metallic bonds and is held together by a sea of delocalized electrons - Kr, a noble gas, is held together only by dispersion forces
An ionic compound has a highly negative enthalpy of solution in water. Is it very soluble or nearly insoluble in water?
Very soluble
What is the vapor pressure of a solution containing 1 mole of glycerin in 4 moles of ethanol at 40 °C?
(Vapor pressure of pure ethanol at 40 °C = 0.178 atm)
0.142 atm