Chemistry
Which of the following represents STP? Select all that apply.
- 1 atm and 273.15K - 101.325kPa and 273.15K - 1 atm and 0 degC - 101.325kPa and 0 degC
The ideal gas law displays the relationship in which of the following? Select all that apply.
- Amontons's law - Charles's law - Boyle's law - Avogadro's law The ideal gas law (PV=nRT) incorporates all of the following relationships: Boyle's Law (P×V), Amontons's Law (PT), Charles's Law (VT), and Avogadro's law (Vn). These laws are combined to determine the relationship between pressure, volume, temperature, and number of moles in the ideal gas law.
Why is it important to know gas properties at STP?
- Because comparison of properties is possible only if the properties are reported against a standard temperature and pressure. - In order to know that exactly one mole of an ideal gas has a volume of 22.4L.
What is true for ideal gases at STP conditions? Select all that apply.
- The standard molar volume is 22.4L. - One mole of any ideal gas has the same volume.
A student wants to crush a can and needs to double the pressure they are applying to the can. Which action can they take to accomplish this? Select all that apply.
- double the force applied and keep the area the same - keep the force the same and decrease the area by 12
According to Amontons's law or Gay-Lussac's law, which states that the pressure of a gas is proportional to the temperature of the gas, what would be the pressure of a gas at absolute zero?
0 If the temperature was absolute zero, the pressure of any gas must be zero if they are proportional, as the law states.
The structure of benzene, including its two resonance forms, is shown below. How many unhybridized p orbitals are present on each of the C atoms in the resonance structures? Use a whole number in your answer.
1 Each of the carbon atoms is bonded to three other atoms with no lone pairs, so the correct hybridization is sp2. That leaves one unhybridized p orbital on each of the carbon atoms, which form the π-bonds that contribute to the resonance.
Which of the following represents standard pressure?
1 atm 101.325 kPa
Normal atmospheric pressure would support a column of water up to what height?
10.3 m A column of water in a barometer would be over ten meters high, which is why this is a terribly inconvenient liquid for measuring atmospheric pressure.
A barometer measures:
Atmospheric Pressure
Which of the following exhibits sp2 hybridization?
BH3 BH3 exhibits sp2 hybridization because the boron atom has 3 electron domains.
Atmospheric pressure is equivalent to what object resting on your thumbnail?
Bowling Ball The pressure we feel at sea level, which is due to the particles in the atmosphere pushing down towards earth, is roughly the same as a bowling ball resting on your thumbnail.
When atomic orbitals of two nuclei overlap, the mutual attraction between a negatively charged electron pair and the two positively charged nuclei forms:
Covalent bond
If the pressure of a gas is kept constant and the temperature (in Kelvin) is cut in half, the volume will __________.
Cut in half
The hybrid orbitals have shapes/orientations that are _______ those of the isolated atoms' atomic orbitals.
Different from When atoms are bonded in a molecule, their individual wave functions are combined. These hybrid orbitals are new orbitals that have new geometry compared to the individual atoms' atomic orbitals.
On a diagram showing the potential energy of two hydrogen atoms according to their Inter nuclear distance, the lowest point will correspond to the
Ideal bond length
What statement is NOT correct about σ bonding?
Rotation around single σ-bonds does not occur easily. Rotation around single (σ) bonds occurs easily because the end-to-end orbital overlap does not depend on the relative orientation of the orbitals on each atom in the bond. Rotation around the internuclear axis does not change the extent to which the bonding orbitals overlap because the bonding electron density is symmetric about the axis. Hybrid orbitals on carbon are used to form the σ-bonds between carbon atoms and between carbon and hydrogen atoms.
What is the hybridization of carbon in carbon dioxide?
SP - CO2 has linear electron pair geometry so the hybridization for this linear arrangement is SP
Under what condition does the volume of the ideal gas approach zero?
when the temperature approaches 0 K
Which of the following correctly represents the standard conditions for temperature and pressure (STP)?
zero degrees Celsius and one atmosphere
Which of the following statements about hybridization are true
- Hybrid orbitals within the same atom have the same energy and shape. - Hybrid orbitals are described mathematically as a linear combination of atomic orbitals. - An atom can have both hybridized and unhybridized orbitals at the same time. Hybridization is a model used to describe the observed bonding in molecules. These hybrid orbitals are described mathematically by a process called LCAO, or the linear combination of atomic orbitals. The hybrid orbitals are equal in size, shape, and energy. sp and sp2 hybridization mixes 1 or 2 p orbitals with the s orbitals, while the remaining p orbital(s) do not form hybrid orbitals.
How many σ-bonds are there in the molecule ethene, C2H4, whose orbital structure is shown below? Use a whole number in your answer.
5 In the ethene molecule, C2H4, there are five σ-bonds. One C−C σ-bond results from overlap of an sp2 hybrid orbital on one carbon atom with an sp2hybrid orbital on the other carbon atom. Four bonds result from the overlap between the atoms' sp2 orbitals with s orbitals of each of the individual hydrogen atoms.
Which of the following is a guideline for determining the the hybridization of a central atom?
Assign the set of hybridized orbitals that correspond to the geometry. Determine the lewis structure of the molecule Determine the number of regions of electron density using VSPER theory (single bonds, multiple bonds, radicals, and lone pairs are each a region).
Which of the following exhibits sp3 hybridization?
CCl4 CCl4 exhibits sp3 hybridization because the carbon atom has 4 electron domains
Which molecule has bond angles that are not reflective of hybridization?
H2Te Tellurium is a large atom, relatively speaking, so hybridization will not come into play for its valence shell, and it will exhibit 90∘ bond angles that are sufficiently described by pure valence bond theory.
What is the pressure exerted by a fluid due to gravity known as?
Hydrostatic Pressure
Under conditions of constant temperature and amount of substance, a plot of pressure vs. volume for an ideal gas will result in __________.
Hyperbolic
Assuming the temperature and the amount of gas are held constant, a plot of volume vs. pressure will give a:
If we plot pressure versus volume, we obtain a hyperbola. This is because pressure and volume exhibit inverse proportionality; increasing the pressure results in a decrease of the volume of the gas. Mathematically, this can be written as follows: P∝1/V P=k/V
If a gas at constant pressure is heated, the volume will __________.
Increase If a gas with constant pressure is heated, the volume will increase. Charles's law states that the volume of a given amount of gas is directly proportional to its temperature on the Kelvin scale when pressure is constant. This can be seen in V1/T1 = V2/T2.
Pressure and volume of an ideal gas are __________.
Inversely Proportional As volume decreases, the pressure will increase if temperature is kept constant, according to Boyle's law
A pi bond involves
Involves a lateral overlap of P orbitals in which electron density is on either sides of the inter nuclear axis. Along the axis, there is a node in which there is no probability of finding an electron Lateral orbital overlap A node
Hybrid orbitals arre not found in:
Isolated atoms
What are the units for the ideal gas constant R when the temperature is in kelvin, the volume is in liters, and the pressure is in atmospheres?
L*atm*(mol^−1)(K^-1)
Which of the following molecules will contain a node, or nodal plane, along the inter nuclear axis?
O_2 and N_2 because it has more than a single bond
Which of the following represents the smallest pressure?
Of the given pressures 1Pa is the smallest. 1Pa= 0.01millibar= 0.001kPa= 1×10−5bar
In order for pi bonds to form, there must be:
Overlap or unhybridized orrbitals
Which is a correct way of stating Boyle's law?
P = k x 1/V PV = k P1V1 = P2V2 Boyle's law states that the volume and pressure of a gas vary inversely if the gas is held at a constant temperature. In other words, if the volume is increased by a certain factor, the pressure will decrease by same factor. All three of these equations are ways of expressing this concept mathematically.
Although standard pressure is defined as 1atm, other units of pressure can also be used. It is common to report standard pressure using SI (standard international) units. What is the abbreviation for the SI unit of pressure?
Pa The SI unit of pressure is the pascal, abbreviated as Pa. Standard pressure is defined as 1atm or 1.01325×105Pa in SI units.
What is the SI unit for pressure?
Pascal
A node is a characteristic in which of the following
Pi Bonds, the orbitals overlap parallel to the internuclear axis, so along the axis itself a node forms
Pressure is inversely proportional to which of the following, assuming all other variables are constant?
Pressure is inversely proportional to area for a constant forces because pressure is the force applied per area: P=F/A
What is the hybridization of boron in boron trichloride (BCl3)?
SP2 There are 3 regions of electron density surrounding the central boron atom, which will arrange themselves in a trigonal planar geometry. The hybridization for this trigonal planar arrangement is sp2.
What is the hybridization of the oxygen atom in a water molecule?
SP3 Oxygen will be sp3 hybridized in a water molecule, because it is surrounded by four electron domains, and will thus need to hybridize all four of the orbitals in its valence shell.
Carbon Oxygen Triple Bond is a...
Short Bond
What counts as an electron domain when assigning hybridization?
Single bonds, multiple bonds, Lone pairs
Which of the following determines the strength of a covalent bond
The amount of overlap for the orbitals involved
The diagram shows energy levels for the unhybridized atomic orbitals for the carbon atom, as well as a set of orbitals for carbon in a molecule. The three orbitals enclosed in the dashed circle are what type of orbitals?
The lower three circled orbitals have energies that are intermediate between the atomic s and p orbitals, making them hybrid orbitals. Because there are three hybrids, they must correspond to three equivalent sp2 orbitals.
Which band is strongest in a carbon-carbon triple bond
The sigma bond
Charles's law is described by which of the following equations?
These are all valid ways of expressing Charles's law. Charles's law states that the volume of a given number of moles of gas is directly proportional to its kelvin temperature when the pressure is held constant V=kT V/T = k V1/T1 = V2/T2
Which unit of pressure is equivalent to mm Hg?
Torr are meant to be identical to millimeters of mercury on a barometer.
Isolated atoms
Use atomic orbitals to house their electrons. Once they form covalent bonds, they will need hybrid orbitals
Which plot will give a straight line?
V vs. 1/P
What can be used to determine the hybridization of central atoms?
VSEPR Theory VSEPR theory can be used to determine the hybridization of central atoms because of its ability to predict electron pair geometries. These geometries are dependent on the number of electron dense regions around a central atom. Single bonds, multiple bonds, radicals, and lone pairs each count as one electron dense region.
Pi Bonds
are created by lateral overlap of unhybridized orbitals that contain at least one node along the inter nuclear plane, which sign abounds occur through overlap of hybridized orbitals. Since s orbitals do not contain nodes, they cannot be involved in making pi bonds
Ideal gas behavior is reasonable for gases that exhibit:
both low pressure and high temperature
What method of walking would apply the least amount of pressure on a surface?
crawling on all fours Your weight stays the same, but if you distribute your weight along a greater area, such as all of your limbs, that reduces the amount of pressure you apply to any surface. This relationship is described by the equation P=F/A.
The orbitals within a set of hybrid orbitals will have:
equivalent shape and energy All orbitals within a set of hybrid orbitals will have identical shape and energy.
If a normal barometer was moved to another planet with the same atmospheric pressure but with less mass, what would be the change in the height of the column?
it would increase With a smaller value for the acceleration due to gravity, the height of the column would increase in order to maintain the same hydrostatic pressure.
The energy of an SP orbital will be:
less than that of a p orbital but greater than that of an s orbital An sp orbital will have an energy in between those of the unhybridized s and porbitals.
Under which set of conditions will the ideal gas law give the best approximation for the properties of a real gas?
low pressure and high temperature The properties of a real gas can be approximated using the ideal gas law under conditions of low pressure and high temperature. These conditions ensure that the gas particles do not interact with one another, or deviate from ideal behavior.
A triple bond always consists of:
one sigma bond and two pi bonds A triple bond will consist of one sigma bond, formed due to direct orbital overlap on the internuclear axis, and then two pi bonds, formed from the lateral overlap of unhybridized...
The diagram shows energy levels for the unhybridized atomic orbitals for the carbon atom, as well as a set of orbitals for carbon in a molecule. The two orbitals enclosed in the dashed circle are what type of orbitals?
p orbitals The upper two, circled orbitals have energies that are the same as the atomic porbitals, making them unhybridized p orbitals. Also note that the lower two orbitals have energies that are intermediate between the atomic s and porbitals, making them hybrid orbitals. Because there are two hybrids, they must correspond to two equivalent sp orbitals, which will leave two p orbitals unhybridized.
Rotation occurs freely around:
sigma bonds Only sigma bonds can rotate freely, as the overlap occurs directly on the internuclear axis, unlike pi bonds, for which rotation would disrupt the orbital overlap.
What is the hybridization of C in CN−?
sp C in CN− has an sp hybridization because of its 2 regions of electron density (1 bonding, 1 non bonding).
An atom with 3 regions of electron density has what hybridization?
sp2 3 regions of electron density would result in an sp2 hybridization.
Gay-Lussac's law assumes that __________.
the volume is held constant the number of moles is held constant According to Gay-Lussac's law, the pressure and temperature of a gas (in degrees Kelvin) are directly proportional. If one increases, the other one will increase as well (and the same for decrease). This relationship is valid as long as the volume and number of moles of gas are held constant.
