Chemistry 102: Exam Two Prep

-Dispersion forces (The only intermolecular forces present in Kr are dispersion forces, which are the result of fluctuations in the electron distribution within molecules or atoms. Since the electrons in an atom or molecule may be unevenly distributed at any one instant, dispersion forces are present in all molecules and atoms. There is only one element present in Kr so no dipole-dipole forces can arise from electronegativity differences, and there are no hydrogen atoms present to participate in hydrogen bonding.)

-Dispersion forces and dipole-dipole forces (There are dispersion forces in NCl3. These intermolecular interactions are the result of fluctuations in the electron distribution within molecules or atoms. Since the electrons in an atom or molecule may be unevenly distributed at any one instant, dispersion forces are present in all molecules and atoms. There are also dipole-dipole forces present in NCl3 because there is a considerable difference between the electronegativities of nitrogen and Cl, and because the geometry of the molecule does not cause the dipoles (which are of equal magnitude) to cancel out.)

-Dispersion forces (The only intermolecular forces present in SiH4 are dispersion forces, which are the result of fluctuations in the electron distribution within molecules or atoms. Since the electrons in an atom or molecule may be unevenly distributed at any one instant, dispersion forces are present in all molecules and atoms. No dipole-dipole forces arise from electronegativity differences between the atoms in SiH4 because the differences are miniscule. Also, the atoms in SiH4 are arranged in the form of a tetrahedron. Since all of the atoms connected to the central atom are identical atoms, any dipoles that do exist will cancel each other out so that there is no net dipole moment.)

-All three forces (There are dispersion forces in HF. These intermolecular interactions are the result of fluctuations in the electron distribution within molecules or atoms. Since the electrons in an atom or molecule may be unevenly distributed at any one instant, dispersion forces are present in all molecules and atoms. These forces increase in strength as molar mass increases because atoms or molecules with larger molar masses tend to have more electrons dispersed over a greater volume. There are also dipole-dipole forces present in HF because there is a considerable difference between the electronegativities of hydrogen and fluorine, and because the geometry of the molecule does not cause the dipoles to cancel out. Finally, HF is capable of hydrogen bonding because it contains a hydrogen atom bonded to a small electronegative element.)

H2CO

CH3OH

CH4

Lower

Lower, Higher, Higher

-The boiling of 10 g of liquid water

q is the heat energy required for the water molecules to undergo the state change from gas to liquid. The change from a higher energy state (steam) to a lower energy state (liquid) results in energy being released. q is negative when energy is released

-Absorbed, Melting, Increase

-The boiling of 10 g of liquid water

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Sublime

Melt

Condense

Deposit

Nothing Because the pressure and temperature are below the triple point, both the gas and the liquid states are not stable. At ?35 ?C, the substance is a solid and will remain as a solid when it is heated

Solid Room temperature is considered to be 21?C and normal atmospheric pressure is considered to be 1 atm. Iodine is a solid at temperatures less than 113.6 ?C while under 1 atm of pressure

Gas According to the phase diagram, iodine is a gas at temperatures higher than 184.4 ?C while under 1 atm of pressure

-Liquids have an indefinite shape and assume the shape of their container -Liquids are not easily compressed -Liquids have a definite volume -Liquids have much higher densities in comparison to gases

-Solids may be crystalline (ordered) or amorphous (disordered) -Solids have a definite volume -Solids have much higher densities in comparison to gases -Solids are not easily compressed -Solids have a definite shape and do not assume the shape of their container

-A gas can be converted into a liquid by cooling -A liquid can be converted to a gas by heating -A gas can be converted into a liquid by increasing the pressure of a gas sample

NH3, SbH3, AsH3, PH3

-Hydrogen bonding occurs when a hydrogen atom is covalently bonded to an N, O, or F atom -A hydrogen atom acquires a partial positive charge when it is covalently bonded to an F atom -A hydrogen bond is possible with only certain hydrogen-containing compounds

None of the above

Ionic bond

Hydrogen bonding

Dispersion force

Dipole-dipole force

Ion-dipole force

-Is an attractive force that results from the electrostatic attraction between an ion and a neutral molecule that has a dipole. Most commonly found in solutions. Especially important for solutions of ionic compounds in polar liquids

-Attractive forces between the positive end of one polar molecule and the negative end of another polar molecule. Dipole-dipole forces have strengths that range from 5 kJ to 20 kJ per mole.

-Type of chemical bond that involves the electrostatic attraction between oppositely charged ions, and is the primary interaction occurring in ionic compounds

-An electrostatic attraction between two polar groups that occurs when a hydrogen atom, covalently bound to a highly electronegative atom such as nitrogen, oxygen, or fluorine

-CH3CN > CH3CH2CH3 > Ar

-Viscosity -Surface tension -Boiling point -Melting point

-Ion-dipole -Hydrogen bonding -Dipole-dipole -London dispersion

London dispersion force

Dipole-dipole

Hydrogen bonding

-Paraffin, C40H82 -Octadecane, C18H38 -Heptane, C7H16 -2,2,3-trimethylbutane, C7H16 -Ethane, C2H6

BF3

>34.6°C

-Mt. Everest, 29,035 feet

-The vapor pressure of a liquid increases with increasing temperature -The relationship between vapor pressure and temperature is not linear, but rather, it is exponential

3.34 kJ

H2O

rate=k[H2O2][I2]

A catalyst provides an alternate mechanism for the reaction

Decreasing the temperature decreases the number of collisions that can occur with enough energy for the reaction to occur

They provide an alternate lower energy mechanism by which the reaction proceeds