chemistry exam 1 questions
d
A saturated solution a) contains more solute than solvent. b) contains more solvent than solute. c) contains equal moles of solute and solvent. d) contains the maximum amount of solute that will dissolve in that solvent at that temperature. e) contains a solvent with only sigma bonds and no pi bonds (i.e. only single bonds, with no double or triple bonds).
ionic
A solid is hard, brittle, and electrically nonconducting. Its melt (the liquid form of the substance) and an aqueous solution containing the substance conduct electricity. Classify the solid. a) ionic b) covalent c) molecular d) metallic
b
A solid is very hard and has a high melting point. Neither the solid nor its melt conducts electricity. Classify the solid. a) ionic b) covalent c) molecular d) metallic
a
An endothermic solution process is described by which of the following? a) ΔH > 0, solution feels cold b) ΔH > 0, solution feels hot c) ΔH < 0, solution feels cold d) ΔH < 0, solution feels hot e) ΔH = 0
d
An exothermic solution process is described by which of the following? a) ΔH > 0, solution feels cold b) ΔH > 0, solution feels hot c) ΔH < 0, solution feels cold d) ΔH < 0, solution feels hot e) ΔH = 0
increases
As temperature increases, the vapor pressure of liquids also
1=a 2=c
Based on the information given in the following figure, determine the stable phase of CO2 under each set of conditions below. 1. At 10 atm and −88°C: a) solid b) liquid c) gas 2. At 4.5 atm and −9°C: a) solid b) liquid c) gas
c
Based on the phase diagram shown below, how will the melting point of the substance change if the pressure is increased above 1 atm? a) the melting point will decrease b) the melting point will remain the same c) the melting point will increase d) The substance will not melt at pressures of 1 atm and above; instead, the solid sublimes to form the gas phase.
CS2 both I2 and CS2 only have dispersion attractions, so they have the best match
Circle the liquid below that would make a good solvent for iodine, I2. Briefly explain your answer. HCl H2O CH3OH NH3 CS2
-All have dispersion. (H2, AR, PF5, only have these) -dipole-dipole= CH2Cl2, H2S, HCN, BrCl5 -h-bonding= NH3, CH3OH, HF (has all three)
Classify the species given below by the intermolecular forces present in a pure sample of each. HCN, NH3, Ar, PF5, CH2Cl2, H2S, CH3OH, H2, BrCl5, HF,
particles (atoms or molecules) are held in fixed positions
How are solids constructed?
the four classes of solids differ in how their particles (atoms or molecules) are held together
How solids are held together?
d
If twice the mass of water has the same amount of heat transferred to it, which of the following graphs best describes the temperature variation? Note that the scales for all the graphs are the same. a b c d
b
In which of the following solvents would you expect KBr to be most soluble? a) C6H14 (hexane) b) CH3CH2OH (ethanol) c) C6H6 (benzene) d) CCl4 (carbon tetrachloride) e) C6H12 (cyclohexane)
b
Is iodine (I2) more soluble in water or in carbon disulfide (CS2)? a) more soluble in water b) more soluble in carbon disulfide
as the temperature goes up, the solubility increases heat + solute (s) <=> solute (aq)
Most solids have endothermic enthalpies of solution (ΔHsolution). Do these solids become more or less soluble in a solution as the temperature of that solution rises? Briefly explain your answer.
ethanol
Predict which of the following liquids has greater surface tension: ethanol (C2H5OH) or dimethyl ether (CH3OCH3).
a
The following compounds are liquid at −10°C: butane (boiling point −0.5°C); ethanol (boiling point 78.3°C); toluene (boiling point 110.6°C). 1. At −10°C, which of these liquids would you expect to have the highest vapor pressure? a) butane b) ethanol c) toluene
c
The following compounds are liquid at −10°C: butane (boiling point −0.5°C); ethanol (boiling point 78.3°C); toluene (boiling point 110.6°C). 1. At −10°C, which of these liquids would you expect to have the lowest vapor pressure? a) butane b) ethanol c) toluene
b
The structures and properties of crystals are determined by the kinds of forces that hold the particles together. We can classify any crystal as one of four types: ionic, covalent, molecular, or metallic. What type of crystals do Si and SiO2 form? SiO2 (silicon dioxide) forms _____ crystals. a) ionic b) covalent c) molecular d) metallic
b
The structures and properties of crystals are determined by the kinds of forces that hold the particles together. We can classify any crystal as one of four types: ionic, covalent, molecular, or metallic. What type of crystals do Si and SiO2 form? Silicon forms _____ crystals. a) ionic b) covalent c) molecular d) metallic
CO2, CH3Br, CH3Br, RbF
Type the following formulas in the boxes below in order of increasing boiling point: RbF, CO2, CH3OH, CH3Br
as the temperature of the H2O rises, the solubility of O2 decreases as H2O drops, leaving less for the aquatic life to survive
Use your knowledge of the relationship between the temperature and the solubility of gases in water to briefly explain why a sudden rise the water temperature in a stream can cause death of aquatic life in that stream
I.A increases as V.P. decreases so compound with lowest b.p. should have the weakest I.A. and the highest vapor pressure so it is acetone.
Using data in the table on the right, indicate which of the following substances would be expected to have the highest vapor pressure at room temperature? Briefly explain your answer.
760 mmHg
What is the vapor pressure of ethanol at its normal boiling point (78.3°C)?
c
Which of the following accurately lists compounds in order of increasing solubility in water a) LiCl, Br2, O2, methanol (CH3OH) b) methanol (CH3OH), LiCl, O2, Br2 c) O2, Br2, LiCl, methanol (CH3OH) d) LiCl, methanol (CH3OH), Br2, O2
d
Which of the following compounds should be soluble in CCl4? a) NaCl b) H2O c) NaOH d) C8H18 e) None of these
d
Which of the following properties indicates very strong intermolecular forces in a liquid? a) very low surface tension b) very low boiling point c) very low critical temperature d) very low vapor pressure
b
Why LiCl has a higher melting point than I2 a) Because LiCl can form hydrogen bonds, and I2 cannot. b) Because LiCl is an ionic compound, and the ion-ion attractions are much stronger than the dispersion forces between the I2 molecules. c) Because LiCl is a solid, and I2 is a liquid. d) Because LiCl is soluble in water, and I2 is not.
d
Why NH3 has a higher boiling point than CH4? a) Because NH3 is a liquid and CH4 is a gas. b) Because NH3 is an ionic compound, and the ion-ion attractions are much stronger than the dispersion forces between CH4 molecules. c) Because NH3 is soluble in water, and CH4 is not. d) Because NH3 can form hydrogen bonds, and CH4 cannnot.
electronegativity
_____ is a measure of an atoms attraction for electrons in a bond, which tells use how much a particular atom "wants electrons
crystalline and amorphous
all solids can exist in two forms called?
strength of the intermolecular attractions (as bp increases so does I.A)
b.p. is directly proportional to..
strength of I.A.
capillary action is a balance between cohesive and adhesive, so no good correlation with
induced dipoles, instantaneous dipoles
dispersion attractions are a consequence of..
SO2
does CO2 or SO2 have a higher b.p?
Cl2
does Cl2 or O2 have a higher b.p?
HF
does Hf or HI have a higher b.p?
ethanol has hydrogen bonding while dimethyl ether does not. so dimethyl ether has weaker I.A.'s and a lower b.p.
ethanol and dimethyl ether have the same molecular formula C2H6O. Ethanol boils at 78.4 degrees celsius. Dimethyl either boils at -23.7 degrees celsius. the structural formulas are:CH3CH2OH and CH3OCH3. explain why the boiling point of the either is so much lower than the boiling point of ethanol.
X-ray diffraction by crystals
how do we know where the atoms are in a solid?
dipole-dipole < dispersion < h-bonding
how strong are each of the intermolecular attractions? list smaller to largest
a=lower, b=the boiling point occurs when the vapor pressure equals the atmospheric pressure. so the normal b.p. will occur when the vapor pressure equals 760 mmHg (or 1 atm). Since at 81.0 degrees celsius the vapor pressure exceeds 760 mmHg, so the boiling point must be less.
if the vapor pressure of carbon tetrachloride (CCL4) at 81.0 degrees celsius is 785 mmHg. a) will the normal boiling boing for CCl4 be higher or lower than 81.0 degrees celsius b) briefly explain your answer
strength of the intermolecular attractions (i.a increases as viscosity increases making it a more viscous liquid)
in general, in the viscosity of a liquid there is a direction relationship between the
constant motion or vibration
particles of matter in any of the three phases are in...
c
select all that apply. which of the following species are capable of hydrogen bonding among themselves? a) H2S b) C6H6 C) CH3OH
larger
the compound with the greater surface tension will have larger or smaller intermolecular attractions?
smaller
the compound with the greater vapor pressure will have larger or smaller intermolecular attractions?
smaller
the compound with the smaller normal boiling point will have larger or smaller intermolecular attractions?
smaller
the compound with the smaller viscosity will have larger or smaller intermolecular attractions?
polar covalent
the following bonds, C-F, C-O, O-H, are ____ bonds
nonpolar covalent
the following bonds, C-H, and C-C are what ___ bonds
the adhesion attractions between the h2o and the glass is stronger than the cohesion attraction between the h2o molecules
the meniscus for water is curved upward at the edges (concave or hollow). Briefly explain in terms of cohesion and adhesion.
polar
the molecules selected are
capillary
the movement of a liquid in a narrow tube is called
strength of the intermolecular attractions ( as I.A increases so does surface tension)
the strength of the surface tension is directly proportional to the
many of the physical properties of that substance in the liquid phase
the types of strengths of intermolecular attractions in a substance will determine
break ALL I.A.
to get from a liquid to gas, must..
temperature
vapor pressure is directly proportional to the
strength of the intermolecular attractions (as I.A increases vapor pressure decreases vise versa)
vapor pressure is inversely proportion to the..
molecular, ionic, covalent network, metallic
what are the four classes of a solid
ionic
what class is CuCl?
metallic
what class is K?
ionic
what class is MgBr2?
molecular
what class is PCl3?
covalent network
what class is quartz?
molecular
what class of solid is C5H12O3?
ionic
what class of solid is CaF2?
metallic
what class of solid is Cu?
ionic
what class of solid is Zn(NO3)2?
covalent network
what class of solid is graphite?
covalent network
what class of solid is silica?
determine many of the physical properties of liquids and solids (which are condensed phases)
what do I.A. determine?
the shape of the molecules
what plays a big part of viscosity?
SiO2
what solid class are covalent in the following substances? CO2, I2, S8, KBr, Mg, SiO2, LiCl, Cr
KBr, LiCl
what solid class are ionic in the following substances? CO2, I2, S8, KBr, Mg, SiO2, LiCl, Cr
Mg, Cr
what solid class are metallic in the following substances? CO2, I2, S8, KBr, Mg, SiO2, LiCl, Cr
CO2, I2, S8
what solid class are molecular in the following substances? CO2, I2, S8, KBr, Mg, SiO2, LiCl, Cr
molecular
what solid class is H2S?
dipole-dipole, dispersion
what type of intermolecular attractions do this molecule have?
dipole-dipole, dispersion, h-bonding
what type of intermolecular attractions do this molecule have?
dipole-dipole, dispersion
what types of I.As are present
dipole-dipole, dispersion, h-bonding
what types of I.As are present
dispersion
what types of I.As are present
molecular bc these solids are held together by the weakest forces (intermolecular attractions)
which class solids should generally have the lowest normal melting point and why?
fluorine
which element is the most electronegative?
c
which of the following would be immiscible with water?
particles are too far apart
why aren't gases condense phases?
bc of the three common isotopes
why hydrogen for h-bonding?
