Chemistry for Engineers Final
lowering the activation energy
A catalyst elevates the rate of the a reaction by:
reactive intermediate
A chemical species created in one step and consumed in a later elementary step is referred to as a(n):
nodal plane
A plane where there is no probability of finding an electron.
There would be no effect. The quarter doesn't add in any significant way to the total pressure of the atmosphere pushing down on the surface. But even if it did, levels in both the dish and the tube would rise by the same amount.
A quarter (25¢ coin) has a density less than mercury. Therefore, if you laid a quarter on the mercury surface in Fig. 5.4 it would float. What would happen to the difference between the mercury level in the tube and the mercury level in the dish if you did this (all things being equal)? Why?
orders of reaction with respect to [X] and [Y].
According to the differential rate law: rate = k[X]^m [Y]^n. In this generic expression, "m" and "n" refer to:
True
As the energy of a system is increase in the energy of the universe, there will be corresponding decrease in the energy of the surroundings.
Q>K because more carbon dioxide gas is released
At the moment when you open a can of soda would you expect Q to be greater than K or K greater than Q? Why? CO2(g) + H2O(l) ⇔ H2CO3(aq)
d
Consider the formation of ammonia. Using VSEPR, which molecule shape best describes the shape of molecule? a. octahedral b. square planar c. trigonal planar d. trigonal pyramidal
decreases
Consider the solubility of BaSO4. If Ba(NO3)2 is added to the solution, the solubility of the barium sulfate:
b
Coulomb's Law states that as the charge on the cation and anion decreases, the force (and potential) of the system: a. increase b. decreases c. remains the same d. becomes quantum mechanically unstable
a
Draw the Lewis Dot diagram of nitrate. How many resonance state are possible? a. 3 b. 2 c. 1 d. 0
increasing the metal surface area by milling
During the formation of MgO from the burning of Mg metal, what steps will result in an increase in the rate of reaction?
True
Entropy is state function.
True
Exothermic reactions in equilibrium will favor the reactants if the system is heated.
tea & sugar and water
For a glass of sweet iced tea. Identify the solute(s) and the solvent(s)
Sodium and chloride ions
For the precipitation reaction, Na2CO3(aq) + BaCl2(aq) = BaCO3(s) + 2NaCl(aq), identify the spectator ions.
ΔE = q + w where q represents the heat released and w represents the work done by the expansion of the gases.
Going back to the demonstration with sugar and KClO3. The reaction equation is given as: C12H22O11(s) + 8KClO3(s) => 12CO2(g) + 11H2O(g) + 8KCl(s). How would the overall change in energy, ΔE, be calculated for this reaction?
3.17 m
Greenville radio station WGTK-FM (94.5 FM) broadcasts on a frequency of 94.5 MHz. What is the wavelength of its signal in meters?
It is a weighted average based on the isotopic abundances as determined by mass spectroscopy.
How are the masses listed for the elements on the periodic table determined?
By plotting volume vs. temperature and extrapolating to zero volume.
How can the value of absolute zero be established by Charles's Law?
It is always the slowest step.
How can we determine which step of a reaction is the rate-determining step?
It depends on how many lone pairs there are.
How can we know if a molecule with five electron pairs is going to be trigonal bipyramidal, square pyramidal, seesaw or some other shape?
The greater the difference in electronegativity, the more polar the bond will be. If the difference in electronegativity exceeds a value of 2.0, the bond is classified as ionic.
How can we predict which bonding interactions will be ionic and which will be covalent?
Look at number of protons first, in a neutral atom the number of protons and electrons has to be the same.
How can you determine how many electrons a particular atom has?
The number of neutrons can be found by subtracting the atomic number from the mass number of that isotope.
How can you determine how many neutrons a particular isotope has?
As the concentration of a common ion increases, its activity becomes less than the concentration and the molar solubility is greater than the calculated value.
How do ion activities affect the measured molar solubility of a salt as compared to the calculated value?
By dividing by the stoichiometric coefficient and putting a negative sign in front of the Δ[reactant].
How do we ensure that the same reaction rate is obtained using either the rate of disappearance of reactants or the rate of appearance of products?
The atoms or molecules are flying around very fast and colide with one another as well as the walls of the container.
How does a gas exert force on the walls of a container?
Energy density is the amount of energy released per gram of fuel burned. Specific heat capacity is the amount of energy released per gram when a substance is cooled.
How does the concept of "energy density" differ from the concept of "specific heat capacity"?
monochromatic
How does the light given off by a LED differ from that given off by an incandescent lamp?
An orderly arrangement (ice) is less probable than a disordered one (liquid).
How does the probability of rolling a certain number on a pair of dice relate to the spontaneous melting of an ice cube?
The half-life is inversely proportional to the first-order rate constant.
How is half-life related to the first-order rate constant?
When ΔH ≅ TΔS.
How is it that a small change in temperature of a chemical reaction is sometimes able to change its direction?
They are inversely related. As one increases, the other decreases.
How is the magnitude of the ionization energy related to the atomic size?
Two
How many carbon atoms would an organic compound have if its line structure is a single straight line?
four
How many electron pairs are in the Lewis structure for NH4+?
a doubling of the rate
If a reaction of a first order with respect to [A], doubling the concentration of [A] will result in:
Helium because it has very little attraction for other helium atoms and it has the smallest occupied volume.
In Table 5.2 which gas has the lowest value for "a" and "b"? Why?
The potential energy stored in the bonds of the sugar molecules is released as kinetic energy as the surroundings are heated.
In class I mixed sugar and KClO3 and ignited the mixture with a drop of sulfuric acid. Which of the following is the best description of this reaction in terms of potential and kinetic energy.
the rates of the forward and reverse reactions become equal
In dynamic equilibrium:
It is very handy for dimensional analysis (Factor-label method).
In general how can the concept of ratio reasoning be an aid to problem solving?
The higher the intensity the light, the more electrons are emitted from the metal, increasing the current.
In the photoelectric effect, what factor determines the number of electrons given off?
One reactant's concentration can be determined by another based on stoichiometry.
In what way are titrations dependent on solution stoichiometry?
Base, because it produces hydroxide ions in solution.
Is NH3(aq) an acid or a base? How do you know?
Deductive Reasoning
Is following an example of inductive or deductive reasoning or both? There is a myth that the wavy, uneven windowpanes in old buildings are that way because the glass has slowly flowed downward over time. But this couldn't be true because glass is an amorphous solid and not a liquid. The real reason why old glass looks this way is because until the early-mid 1800s, most window glass was made using a process called the crown method. The glass was blown, flattened, heated and spun, yielding a sheet that was relatively cheap to produce. It was also rippled and thicker in some places than in others.
Not reporting measured values to the correct number of significant figures could be a lie about how precisely a measurement was made.
It the use of the correct number of significant figures encouraged by a Christian worldview?
good precision but poor accuracy
Measuring the density of aluminum using aluminum cans, but failing to take into account the thin layer of polymer that is applied to the inside of the can is an example of a type of measurement that has _______ .
The molarity decreases as the solvent expands.
Most chemical substances expand when heated. Ice and rubber are notable exceptions. What happens to the molarity of a solution when the solution is heated? (assume that no evaporation is occurring)
d
Multiple bonding results from the sharing of more than one electron pair. An example of this phenomenon is the double bond. In this case, the second bond is characterized as: a. a second single bond b. a plasmodic state c. a sigma bond d. pi bond
d
Of the following substances which is more reactive? a. SiO2 b. CaCl2 c. starch d. F2
Groups. Because elements of the same group will have similar chemical properties.
On the periodic table, which is more important, the groups or the periods? Why?
True
Process that are spontaneous only at lower temperatures are referred to as enthalpy driven reactions.
True
Products appear in the numerator of the reaction quotient.
Iron can form cations with 2+ and 3+ charges.
Sometimes iron chloride is an orange-brown color and sometimes it is a greenish-yellow color. Why?
enthalpy, internal energy, entropy
The Gibbs free energy change, ΔG, is the fourth thermodynamic state function introduced in your text. What were the previous three?
b
The assignment of electrons in Lewis Dot is limited to: a. all electrons b. valence election c. the "d" sub-orbital d. only those in the first group
C(graphite) turns to C(diamond)
The best example of a spontaneous process.
It is constantly reacting, but the forward reaction has the same rate as the reverse reaction, so the concentrations are staying the same.
The concentration of ozone in the stratosphere is a dynamic equilibrium. What does that mean?
heterogeneous equilibrium
The decomposition of dolomite: MgCO3(s) <--> MgO(s) + CO2(g) represents a(n):
True
The instantaneous rate of a reaction is determined using the slope of a lone tangent to the curve of the change of concentration versus time.
The -ate ending indicates the highest number of oxygens possible where there are two possibilities. Each of these anions is the option with more oxygen
The phosphate and sulfate anions both have four oxygens but the carbonate and nitrate anions only have three a piece. So why do all four anions have -ate endings?
d
The rubidium cation has a correct charge of: a. 3+ b. 2+ c. 1- d. 1+
8.314472 J/mol*K
The universal gas constant can be expressed in a variety of different units. What is it in the SI system?
True
Thermal energy is directly related to the motion of atoms and molecules of the object in question.
increases
Two 6.5L flasks are joined by a 150 mL tube with a stop cock. If 0.25 moles of nitrogen are held in the left flask and the right flask is empty, what happens to the entropy of the system upon opening the valve between the flasks?
Liquid Ammonia
Water is an amphoteric substance. Are there any other amphoteric substances described in this section (12-7)?
Carbon Dioxide and Water
What are the products of the complete combustion of any organic compound?
Both are energy transfers, but heat involves a flow of energy between objects having different temperatures and work involves a force moving a mass some distance.
What are the similarities and differences between heat and work?
hydronium ions
What conjugate acid is formed when carbonic acid is dissolved in water?
It factors in the number of collisions that have enough energy but do not lead to a reaction.
What does the preexponential factor of the Arrhenius equation tell us about a reaction?
Slow the process down by using small incremental steps.
What does the relationship ΔG = -wmax tell us about how to improve the efficiency of a real process?
An antiknock agent
What is MTBE?
Metallic bonds share electrons with a large group of atoms whereas covalent bonds usually share a pair of electrons between two nuclei.
What is the difference between a metallic bond and a covalent bond?
Strong Electrolytes dissociate completely, while weak electrolytes dissociate only partially.
What is the difference between a strong electrolyte and a weak one?
Sigma bonds overlap end-to-end and Pi bonds overlap side-to-side
What is the difference between sigma bonds and pi bonds?
Tetrahedral
What is the geometry of NH4+?
Gasoline
What is the most likely limiting reactant in a gasoline engine?
sp3
What is the orbital hybridization of NH4+ ?
They are both calculated from the same basic equation (which tells you the ratio of concentrations), but the equilibrium constant is the value of the equation at equilibrium, while the reaction quotient is from any other time.
What is the relationship between the equilibrium constant and the reaction quotient? What do they have in common and what is different?
They are both slopes of the concentration vs. time curve and as the time interval gets shorter and shorter they get closer and closer together. They would also be the same when the rate is constant.
What is the relationship between the instantaneous rate and the average rate? Under what circumstances would they be the same?
If you multiply the mole fraction by the total pressure you get the partial pressure of that gas.
What is the relationship between the mole fraction of a gas and its partial pressure?
22.4 L, This value is useful because volumes of gas are often measured in liters. This conversion factor allows you to convert from liters of gas to moles which is necessary in stiochiometric problems.
What is the volume of one mole of an ideal gas at standard conditions? Why is this an useful value to know when solving problems involving the stoichiometry of reactions containing gases?
There are no insoluble salts.
When I was in college we had to memorize a list of insoluble salts. Now we have tables of solubility product constants instead. Why the change?
A continuous pour would have taken too long to cool.
When the Hoover Dam was built the dam was not built in a single continuous pour. Instead, the ground where the dam was to rise was marked with rectangles, and concrete blocks in columns were poured, some as large as 50 feet (15 m) square and 5 feet (1.5 m) high. Based on what you've read, why did the engineers decide to build the dam in sections like that?
Which ever one is physically reasonable.
When using the quadratic formula to solve for an equilibrium concentration, how do we know which root is the correct one to use?
The largest one
Which "K" value indicates a reaction most favoring the formation of products?
c
Which of the following atoms is likely to be involved in a covalent bond? a. 1s^22s^22p^63s^2 b. 1s^22s^22p^6 c. 1s^22s^22p^63s^23p^3 d. 1s^22s^22p^63s^23p^6
a, b, c
Which of the following compounds would be soluble in water at room temperature? (a) NH4Cl (b) KOH (c) Ca(CH3COO)2 (d) Ba3(PO4)2
b
Which of the following has the largest ionic radius? a. Al^3+ b. I- c. S d. K+
a
Which of the following has the largest radius? a. I- b. Br c. Cl- d. F
That you would want to make the scarcest or most expensive material the limiting reactant.
Which of the following is an important implication for engineering of the concept of limiting reactants?
b
Which of the following is the correct charge for a bromine anion? a. 1+ b. 1- c. 0 d. 2-
The Fahrenheit scale
Which temperature scale is more precise, the Fahrenheit, Celsius or Kelvin?
Lower energy states are more stable.
Why are a majority of spontaneous chemical reactions exothermic?
They are closer together and therefore attract or repel each other more. Also, the molecular volume plays more of a role.
Why do gases at high pressure deviate from ideal behavior?
Continuous wavelenghts are usually the result of thermal energy being emitted, whereas discrete wavelengths are the result of absorption and emission at a particular energy.
Why do some materials give off a continuous range of wavelengths and others only discrete wavelengths?
Some substances have more chemical bonds where energy can be stored.
Why do some substances have higher molar heat capacities than others?
Because the units are squared or cubed or whatever by the order of the reaction.
Why do the units of a rate law depend on the order of the reaction?
Differential rate laws are used to determine how the rate changes with the concentration but integrated rate laws allow us to determine the concentration of a reactant or product at any time.
Why do we use differential rate laws in some cases and integrated rate laws in others?
Heat flows due to random collisions of molecules and an increase in temperature increases the random collisions of molecules. Work, by contrast, requires moving a mass some distance. To yield a net movement, there must be a direction associated with a motion and that direction implies that there is an order to the motion.
Why is it impossible to convert heat completely to work?
Heat is a process, not a quantity. We could say that a burning log produces a lot of heat.
Why is it not correct to say that a burning log contains a lot of heat? What would be the proper way to express the relationship between a burning log and heat?
Because they would have to occupy the same physical space.
Why is it that two electrons in the same atom cannot have same set of four quantum numbers?
Because most chemical reactions take place under constant pressure conditions.
Why is the concept of enthalpy more useful to a chemist than the concept of internal energy?
When a liquid is converted to a gas, all the molecules in a sample must overcome whatever intermolecular forces are present.
Why is the heat of vaporization of water much larger than the heat of fusion of water?
In a collection of molecules some move very fast and others are almost standing still.
Why isn't it correct to think about molecules as having a particular speed?
It is the solutions to the Schrödinger equation that give us quantum numbers.
Why would a introductory chemistry text like yours introduce the Schrödinger wave equation, HΨ=EΨ?
The concept of electron affinity connected to Hund's rule
With electron affinity, we deal with energy required to make an anion out of a neutral atom. Hund's rule states that electrons will tend to be alone in a particular orbital if they have the option, they pair only if they have to. If we have an atom that has one valence electron instead of two in the outer orbital the energy required to make than neutral atom an anion should be greater. More energy is needed in that situation because Hund's rule states that electrons do not want to be placed together because like charges repel each other. If we have orbitals that are all filled in a neutral atom and want to add energy to make that an anion, the energy needed to make that happen should go down because it would be the only electron in its orbital.
