Chemistry (organic) intramolecular forces CH. 3
Which of the following are true about electronegativity?
-Electronegativity generally increases as you move across the groups in a period (from left to right) on the periodic table. -Electronegativity is a measure of the tendency of a bonded atom to attract electrons towards itself -Atoms with higher electronegativity have a stonger attraction to the electrons in their bonds.
Dipole-dipole attractions increases in magnitude with:
Increasing bond polarity
How do intermolecular forces compare with intramolecular forces in terms of strength?
Intramolecular forces are typically much stronger
Who is credited with deriving the electronegativtiy values of the periodic table?
Linus Pauling
At room temperature, n-pentane is a liquid and neopentane (2, 2-dimethylpropane) is a gas. Both compounds are nonpolar hydrocarbons. Which of the following forces is primarily responsible for this difference?
London dispersion forces
Which of the following has the largest dipole moment? NCl3 BF3, CO2, CF4
NCl3
Which of the following will NOT exhibit hydrogen bonding to the N atom? NH3 (CH3)2NH NH+4 CH3NH2
NH+4 The ammonium ion does not have any lone pairs available on the nitrogen to form hydrogen bonds.
Which of the following will NOT generate dipole-dipole interactions? HCl CO LiBr O2
O2
Which of the following has dipole-dipole attractions? CO2, F2, FeCl2, PCl3
PCl3
Matter that is super-ionized such that it is no longer strictly atomic is a:
Plasma Though it can be considered gaseous in a sense, the highly ionized character of a plasma makes it behave much differently than other forms of matter
In the PF5 molecule, what is the geometry of the bond dipole for one PF bond?
Vector pointing toward F
Which of the following conditions is/are true when a transition between states is observed in the order of solid→liquid→gas? increase in kinetic energy decrease in intermolecular forces both a and b neither a nor b
both a and b The differences in the properties of a solid, liquid, or gas reflect the strengths of the attractive forces between the atoms, molecules, or ions that make up each phase. The phase in which a substance exists depends on the relative extents of its intermolecular forces (IMFs) and the kinetic energies (KE) of its molecules. As a substance goes from solid to liquid to gas, the kinetic energy of the particles increases and intermolecular forces experienced by the particles decrease.
Which halogen is a liquid at room temperature? fluorine chlorine bromine iodine
bromine
Which of the following equations accurately represents bond dipole moment?
m=Qr The magnitude of a bond dipole moment (m) is given by the formula, where Q is the magnitude of the partial charges (determined by the electronegativity difference) and r is the distance between the charges
The process of going from the solid to liquid phase is called
melting
Which among the following has the highest melting point? methanol CH3F CH4 C2H6
methanol
Which of the following will exhibit hydrogen bonding? Br2, F2, I2, none of the above
none of the above Molecules with F-H,O-H, or N-H have partial charges that allow for a very strong dipole-dipole attraction to develop known as hydrogen bonding. None of these molecules are capable of hydrogen bonding because they do not contain F-H,N-H, or O-H bonds.
In general, the type of magnitude of intermolecular forces that are present in a substance will determine that substances:
physical properties
An electrically charged object can be used to attract:
polar molecules
Which physical form of matter has definite shape and volume?
solid
Which substance below will require the most heat energy to enter the gas phase? Crystalline solid, liquid, gas
solid
Which option shows the phases in order of increasing kinetic energy contained within a sample?
solid, liquid, gas
Intermolecular forces are greatest in
solids
What type of bond will form between two atoms that have a difference in electronegativety equal to 0.2?
A pure covalent bond.
The net dipole of a molecule is always
A combination of the individual bond dipole
Which of the following statement(s) about dispersion forces are correct? Larger and heavier atoms and molecules tend to exhibit stronger dispersion forces than smaller ones. Dispersion forces are weaker between molecules that are not easily polarized. Dispersion forces are stronger between molecules that are easily polarized. All of the above
All of the above Dispersion forces are present between any two molecules (even polar molecules) when they are almost touching. Dispersion forces are present between all molecules, whether they are polar or nonpolar. Larger and heavier atoms and molecules exhibit stronger dispersion forces than smaller and lighter ones. In a larger atom or molecule, the valence electrons are, on average, farther from the nuclei than in a smaller atom or molecule. They are less tightly held and can more easily form temporary dipoles. London dispersion forces tend to be stronger between molecules that are easily polarized and weaker between molecules that are not easily polarized.
Which of the following statement(s) about dispersion forces are correct? -Larger and heavier atoms and molecules tend to exhibit stronger dispersion forces than smaller ones. -Dispersion forces are weaker between molecules that are not easily polarized. -Dispersion forces are stronger between molecules that are easily polarized. -All of the above
All of the above Dispersion forces are present between any two molecules (even polar molecules) when they are almost touching. Dispersion forces are present between all molecules, whether they are polar or nonpolar. Larger and heavier atoms and molecules exhibit stronger dispersion forces than smaller and lighter ones. In a larger atom or molecule, the valence electrons are, on average, farther from the nuclei than in a smaller atom or molecule. They are less tightly held and can more easily form temporary dipoles. London dispersion forces tend to be stronger between molecules that are easily polarized and weaker between molecules that are not easily polarized.
The molar mass of I2 is 254gmol, and that of astatine (At2) is 420gmol. Which one has the higher melting point and why? I2, because it has less molar mass, and, therefore, the dispersion forces between molecules are smaller. I2, because it has the higher molar mass, and, therefore, the dispersion forces between molecules are higher. At2, because it has higher molar mass, and, therefore, stronger dispersion forces. At2, because it has less molar mass, and, therefore, stronger dispersion forces.
At2, because it has higher molar mass, and, therefore, stronger dispersion forces.
Which of the following will have the highest boiling point? C3H8 CH3COOH CH4 C2H6
CH3COOH
Which halogen is a liquid at room temperature? -Fluorine -chlorine -Bromine -Iodine
Bromine
Which molecule will NOT participate in hydrogen bonding? H2O CH3OH CH3OCH3 CH3CH2OH
CH3OCH3
Consider the structural formulas for methanol, CH3OH, and ethane, C2H6. Which has a higher melting point and which statement substantiates the answer?
CH3OH because it has a hydrogen directly bonded to an oxygen.
Which type of group will NOT generate hydrogen bonds? F-H O-H N-H C-H
C-H Only when hydrogen is bonded to one of the three most electronegative elements, fluorine, oxygen, or nitrogen, will hydrogen bonding occur.
Identify the substance that does not show dipole-dipole interactions between molecules. water HCl CCl4 none of the above
CCl4
Identify the substance that does not show dipole-dipole interactions between molecules water, HCl, CCl4
CCl4 A stronger intermolecular force result when molecules have permanent dipoles. Polar molecules have a partially positive charge on one side and a partial negative charge on the other side--a separation of change called a dipole. This attractive force is called a dipole dipole attraction-- the electrostatic force between the partially positive end of one polar molecule and the partially negative end of another. Dipole-dipole attractions in polar molecules are stronger than the dispersion
Consider the structural formulas for methanol, CH3OH, and ethane, C2H6. Which has a higher melting point and which statement substantiates the answer? CH3OH because it has a hydrogen directly bonded to an oxygen. C2H6 because it has hydrogen directly bonded to oxygen. CH3OH because it has a hydrogen directly bonded to a methyl group. C2H6 because all of its hydrogens are directly bonded to carbon.
CH3OH because it has a hydrogen directly bonded to an oxygen. Methanol has a molecular weight of 32 grams per mole and a melting point of −97.8∘C. Ethane has a molecular weight of 30 grams per mole and a melting point of −172∘C. The hydroxyl group on methanol has hydrogen directly bonded to oxygen, so it can hydrogen bond, while ethane cannot. The hydrogen bonding is responsible for its higher melting point.
Which of the following CHBr3, CHCl3 will have a higher boiling point?
CHBr3
Which molecule would exhibit the strongest dipole-dipole interactions? CH4 CH3Cl CH2Cl2 CHCl3
CHCl3
Hydrogen bonding is responsible for: the structure of the DNA backbone DNA base pairing the number of bases in DNA none of the above
DNA base pairing
Between C2H6, CO2, H2O, H2 which of the following will participate in dipole-dipole interactions?
H2O
The hydrogen bond occurring between which two molecules would be the strongest? NH3 and NH3, NH3 and H2O, H2O and H2O, H2O and HF
H2O and HF
Which of the following will have the highest boiling point? CH2O CH3F H2O2 they have the same boiling point
H2O2
Which molecule will have a net dipole? SF6, PCl5, NH4+ H2S
H2S
Which of the following does NOT exhibit hydrogen bonding? H2O HBr HF H3N
HBr
Which of the following does NOT exhibit hydrogen bonding? H2O HBr HF H3N
HBr Hydrogen bonding occurs between H-F, H-O, and H-N groups.
Polar molecules have a partial positive charge on one side and a partial negative charge on the other side—a separation of charge called a dipole. Which of the following molecules has this kind of a dipole? CH4 CO2 C6H6 HCl
HCl A stronger intermolecular force results when molecules have permanent dipoles. Polar molecules have a partial positive charge on one side and a partial negative charge on the other side—a separation of charge called a dipole. Consider a polar molecule such as hydrogen chloride, HCl. In the HCl molecule, the more electronegative Cl atom bears the partial negative charge, whereas the less electronegative H atom bears the partial positive charge. An attractive force between HCl molecules results from the attraction between the positive end of one HCl molecule and the negative end of another. This attractive force is called a dipole-dipole attraction—the electrostatic force between the partially positive end of one polar molecule and the partially negative end of another. Intermolecular attractions in polar molecules are stronger than the those between nonpolar molecules of similar mass, which only consist dispersion forces.
Which fact adequately explains why HCl has a higher boiling point than F2?
HCl is a polar molecule and F2 is not
Which fact adequately explains why HCl has a higher boiling point than F2?
HCl is a polar molecule, F2 is not. The dipole present in HCl allows it to generate dipole-dipole interactions, while F2 is strictly nonpolar. The stronger intermolecular forces cause HCl to remain liquid until higher temperatures are reached.
Which of the following will have the highest boiling point? HCl HF HBr they have the same boiling point
HF
Which molecule can exhibit hydrogen bonding? CH4 HOCH2CH2OH O2 H2CO
HOCH2CH2OH
Arrange the halogens Br2, I2, F2, and Cl2 in the order of decreasing boiling point.
I2 > Br2 > Cl2 > F2
Which of Cl2 or I2 has the higher boiling point and why?
I2 because it has higher molar mass, and therefore, stronger dispersion forces.
Which of Cl2 or I2 has the higher boiling point and why? Cl2 because it has the higher molar mass, and, therefore, stronger dispersion forces. I2because it has less molar mass, and, therefore, less dispersion forces. Cl2because it has less molar mass, and, therefore, stronger dispersion forces. I2because it has higher molar mass, and, therefore, stronger dispersion forces.
I2because it has higher molar mass, and, therefore, stronger dispersion forces. The molar mass of Cl2 is 70.9gmol, and that of I2 is 253.8gmol; I2 has a higher molar mass and, therefore, stronger dispersion forces. It has the higher boiling point.
ICl is a polar molecule and Br2 is a non-polar molecule. Which molecule will have a higher boiling point? ICl Br2 Both ICl and Br2 will have the same boiling point. There is not enough information to answer this question.
ICl
Between ICl and Br2 which of the following would have the higher boiling point?
ICl- Compounds with stronger intermolecular forces will have higher boiling points (ion ion > hydrogen bonding > dipole dipole > london dispersion). Br2 is nonpolar and only has dispersion forces. ICl is polar and has dipole-dipole attractions so it will have the higher boiling point.
Which molecule will have a net dipole? CO2, SO3, CH4, BF3
SO2
Based on molecular geometry, which of the following molecules could have net dipole moments if all bonds present were polar? CS2, SeS2, PCl3 (P is the central atom) ClNO (N is the central atom)
SeS2, PCl3 (P is the central atom), ClNO (N is the central atom)
Where can plasma be found?
The sun The incredibly high temperature inside the Sun strips electrons from atomic nuclei to general plasma. None of the other objects are hot enough to do this (the rock, a snowflake, a hot spring)
At a sufficiently low temperature, a liquid does not have enough kinetic energy to overcome intermolecular attractions, and changes into:
a solid
When you find dew on a leaf in the morning, it formed via:
condensing
Which of the following is NOT weaker than a hydrogen bond?
covalent bond
Hydrogen bonding is technically a type of:
dipole-dipole attraction Hydrogen bonds are exceptionally strong dipole-dipole interactions.
which type of intermolecular forces are the strongest in CH3Cl?
dipole-dipole interactions
Which type of intermolecular forces are the strongest in CH3Cl? hydrogen bonding dipole-dipole interactions dispersion forces ionic bonding
dipole-dipole interactions CH3Cl is a polar molecule because the chlorine is far more electronegative than the carbon atom. Since it is polar, it will have a permanent dipole and dipole-dipole interactions will be the strongest intermolecular forces. It cannot form hydrogen bonds because hydrogen atoms are not bonded to N, O, or F atoms. Dispersion forces will still be present, but the permanent dipole of CH3Cl makes the dispersion forces insignificant.
What is the relationship between dipole moment and the distance between the charges?
directly proportional
Hydrogen bonds are formed between hydrogen and: nonpolar molecules cations electronegative atoms all of the above
electronegative atoms
Intermolecular forces are all some kind of:
electrostatic attraction
A substance that has no fixed shape or volume is a:
gas
Which of the following would have the highest kinetic energy?
gas
Which of these gas, liquid, or crystalline solid would likely have the weakest intermolecular forces?
gas
Polar molecules have attractive dipole-dipole interactions when the dipoles are arranged in which of the following geometries? head-to-tail: →→ head-to-head: →← side-to-side, antiparallel: ↑↓ side-to-side, parallel: ↑↑
head-to-tail: →→ side-to-side, antiparallel: ↑↓ Dipole-dipole interactions can be attractive for both head-to-tail, where the positive end of one dipole is directed towards the negative end of the other dipole, and for side-to-side, where the positive end of one dipole is next to the negative end of the other. Both of these arrangements become repulsive if one of the dipoles is reversed.
Stronger dipole-dipole interactions will typically result in a :
higher boiling point
Hydrogen bonding results in:
higher boiling points, higher melting points, and higher heats of vaporization
Which of the below factors contribute to making hydrogen bonds so strong? (Select all that apply) highly concentrated partial charges large differences in electronegativity between the two atoms in the bond strong dispersion forces small size of the atoms
highly concentrated partial charges large differences in electronegativity between the two atoms in the bond small size of the atoms
Intermolecular forces are primarily responsible for:
holding together molecules in a material
Water freezes at 0∘C and CO freezes at −250∘C. Which type of intermolecular force accounts for this difference in freezing point between the two compounds?
hydrogen bonding
Which of the following is the strongest intermolecular force?
hydrogen bonding
Which type of intermolecular force is strongest in HF ? hydrogen bonding dipole-dipole interactions dispersion forces ionic bonding
hydrogen bonding
Which type of intermolecular force predominates between NH3 molecules? hydrogen bonding London dispersion forces covalent interactions ionic bonding
hydrogen bonding An isolated ammonia molecule, just like a water molecule, can form strong hydrogen bonds with either hydrogen bond donors or acceptors. Ammonia is more basic than water, and, therefore, ammonia is a better hydrogen bond acceptor than water. Each ammonia molecule can hydrogen bond to two others.
Which of the following is a strong type of dipole-dipole attraction that involves molecules with F-H, O-H, or N-H? hydrogen bonding dipole-dipole bonding dispersion force all of the above
hydrogen bonding Molecules with F-H,O-H, or N-H have highly concentrated partial charges that allow for a very strong dipole-dipole attraction to develop known as hydrogen bonding.
Which of the following forces is characteristic of some of the compounds with the highest boiling point?
hydrogen bonding Compounds with stronger intermolecular forces will have higher boiling points. In order of decreasing strength, the types of intermolecular forces are ranked as follows: ion-ion attractions > hydrogen bonding > dipole-dipole attractions > london dispersion forces.
Which of the following shows a correct arrangement of intermolecular forces from strongest to weakest? hydrogen bonding > London dispersion forces > dipole-dipole interactions hydrogen bonding > dipole-dipole interactions > London dispersion forces London dispersion forces > dipole-dipole interactions > hydrogen bonding dipole-dipole interactions > London dispersion forces > hydrogen bonding
hydrogen bonding > dipole-dipole interactions > London dispersion forces
The kinetic energies of molecules are responsible for:
increasing the distance between particles.
Which is the strongest type of intermolecular force?
ion-ion ion-ion forces are the strongest intermolecular force because they involve formal charges.
which of the following describes the gaseous state of matter?
it expands to fill its container particles are far away from one another, and experience little attraction
The ___________ the dipole moment, the ________ the boiling point of the compound.
larger, higher
A substance that has a fixed volume, but no fixed shape is a:
liquid
Which of the following statements is true for a substance that undergoes a change of phase from liquid to solid? -The kinetic energy of the particles is less than the energy of the intermolecular attractions -The kinetic energy of the particles is greater than the energy of the intermolecular attractions -A change of phase will not affect the kinetic energy of the particles -none of the above
the kinetic energy of the particles is less than the energy of the intermolecular attractions
Hydrogen bonding is:
the strongest van der Waals force Hydrogen bonds are the strongest dipole-dipole attraction, and are therefore considered to be the strongest type of van der Waals force.
Hydrogen bonding is responsible for: the unexpectedly high boiling points for hydrides in period two the increasing boiling points for hydrides going down a group the low boiling points of nonpolar molecules none of the above
the unexpectedly high boiling points for hydrides in period two The boiling points for water, ammonia, and hydrogen fluoride defy the linear trend put forth by other hydrides in their groups. Their hydrogen bonding causes them to boil at much higher temperatures than expected.
Hydrogen bonds are exceptionally strong because:
they involve exceptionally strong dipoles hydrogen atoms are very small fluorine, oxygen, and nitrogen atoms are relatively small
What can be used to represent bond dipole moments?
vector
