Unit 3 Test Mcq Focused Flashcards
Which if the following best describes how the model is limited in its depiction of the phenomenon
It doesn’t show how the temporary fluctuating dipoles of the molecular electron cloud results in a net force of attraction between the molecules
If the substance is an ionic compound what must be true about the aqueous solutions
Test the electric conductivity of the aqueous solutions to see if it’s ionic
At room temp why is I2(s) a molecular solid
It is not a good conductor of electricity because it’s VE are localized in bonding and non bonding pairs
When there is fewer molecules of product than reactant what happens
The pressure decreases
When absolute temperature is doubled what is also doubled
Pressure
Measurements that must be made to calculate the molar mass of gas(like they fire experiment we did) must include all EXCEPT
Mass of the water in the apparatus
When comparing flasks use what formula
PV=nRT
Usually in this situation V is a constant however
If the partial pressure elf each has is half its initial pressure then wha happens to the final total pressure
The final total pressure is half the sum fo the initial pressure of the 2 gases
Liters of sample can affect what
The total pressure
Equal masses of three different ideal gases depends on
The relative molecular masses of X Y and Z
Atoms will escape faster for, a container if they have
A higher average speed which is due to the weight of the atom
When gas is added to a rigid container at a constant temp the average speed of the gas molecule…
Stays the same
If a sample of a gas ic cooled the average speed of the molecule
Decreases
At standard temp and pressure, various # of mol samples still have the same
Average molecular kinetic energy
If area under the graph is the same for all gases in maxwell distribution graph that means that
The molecular masses of the gases have the same average KE
If the temperature is held constant what happens to the KE
The KE stays the same
If 2 flexible containers are held at the same temp and gas the volume of the one gas container is not
The same as the volume of the other gas container
A gas deviates more from ideal behavior at high temperatures than another gas because
The particle volume of a gas is greater than the other gas
The ideal gas law does not include a factor for molecular
Volume
When the average distance between molecules is greater
The behavior of a sample is more like an ideal gas
Less force in collisions means what about the ideality of a gas?
That it’s more ideal
Low pressure can be a result of what with IMF
Strong IMF
The ideal gas law best describes what type of gas molecules
A diatomic gas
No polar
Molarity equation
Moles of solute/ moles of volume
Concentration is with what variable
M
Molarity
What is a concentration
Molarity, what is said in the original solution, does not change
When volumes are additive it is saying
You can’t simply add the moles you have to multiply by the mL sample
Which chem tool has the greatest accuracy for measuring L
The 100 mL volumetric flask
When solving concentration or molarity problems PAY ATTENTION TO
of moles of the element you are solving for!!
If a molecule is np and another is polar, are there IMF between the two?
Yes there are definitely LDF and possibly also dip-dip
Is nacl np
No it’s polar
What gas can be collected by a displacement of water
H2
When asked about ions present in significant concentrations don’t include
The ions that are in both molecules
Which of the following techniques is most appropriate for the recovery of solid molecules from an aqueous solution of a molecule
Evaporation to dryness
I’m looking at a graph to find the greatest percentage of which compound can be recovered by look at what
look at the slopes of the molecules
for paper chromatography if the solvent is polar and stationary what’s products will travel up deplete the fastest(np or p)
polar product will travel the furthest up the paper
The substance that would be initially present in higher concentration in the distal it is because(identify bonds and what needs to happen to them)
it has more C-C bonds to break
When asked to identify X and Y in paper chromatography don’t pay attention to the polarity of the paper pay attention to…?
The polarity of the solution at the bottom
hexane for example
Why would one guest be able to absorb ultraviolet light but not visible light in the other gas be able to absorb both
because visible light may produce transitions between energy levels in one gas but not the other
The band in the region corresponding to shorter wavelength shows what(think about absorbance in comparison to longer wavelengths)
A lower absorbance than the band in the region corresponding to longer wavelengths
what is h in frequency equations
planks constant
6.626*10^-34 J
nano is to what power?
-9
speed of light
3*10^8 m/s
A gas mixture at 0°C and one atm contains .01 moles of H2, space .015 moles of O2, space and .025 moles of N2. Space assuming ideal behavior what is the partial pressure of hydrogen gas H2 in the mixture
about .20 atm because each to comprises i20% of the total number of moles of gases
Doubling the number of moles does want to partial pressure
doubling the number of moles doubles it’s partial pressure
What can polar H2O molecules do to the electron clouds of O2 molecules
they can induce temporary dipoles on the electron clouds
Molecules dissolve in a solution if
they are like substances for example it is a polar solution and there’s a polar solvent or vice versa (with nonpolar)
What do molecular models not show that results in a net force of attraction between molecules
it does not show how the temporary fluctuating dipoles of the molecular electron clouds result in a net force
When considering boiling point consider
more polarizable more electrons the most importantly the IMF
Which of the following is not shown in a model of flasks with particles but explains why a flask must contain certain gas
The strength of the IMF between the particles in the liquids
What is the order of the IMF
strongest is hydrogen bonding then dipole dipole forces then London dispersion forces
Which one has a higher melting points MgS or NaCl
MgS
because it has charges of +2 in -2 while NaCl has charges of +1 and -1
what does lower melting point mean
in relation to IMF
lower melting point aligns with higher boiling points meaning it has stronger IMF
what is boron nitride
type of solid
a covalent network
what so a covalent network
a network solid of atoms connected by covalent bonds w fixed bond angles
is ionic bonding soluble in water
yes
are dipole dipole forces soluble in water
yes
is ionic bonding soluble in hexane(polar)
no
will a solid ionic compound conduct electricity why or why not
no becuase the particles aren’t free to move
will an aqueous ionic compound conduct electricity
yes because the electrons are now free to move
what happens to the temps of different gases at thermal equilibrium
they stay the same
when considering the greatest average speed of the particles consider
the lowest molar mass and highest temp
greatest MM is determined by what
most # of particles
when asked about which molecule will have the largest dipole consider
electronegativit and polarity
when asked which molecule will form h bonds with other molecules consider
if there is an h bond in that molecule itself
which is the IMF exhibited by a pure sample of Cs2
LDF only
which molecule would have the largest dispersion forces
look for strongest IMF
when ranking the lattice energy of the following formulas consider
identify bond strength so identify ion charges
which do you do first when identifying bond strength
identity charge first or ion size
charge first
when charges are equal what do you sue to break the tie when identifying bond strength
use ion size
if considering highest vapor pressure look for
strongest IMF
