PHY S Exam 3
For the pictures of molecules below, the gray balls represent carbon atoms and the white balls are hydrogen atoms. The molecules belong to a family called the hydrocarbons. These questions test if you can recognize patterns in molecular families and bonding around carbon atoms and then reason from them to make predictions.
C2H4
The chemical formula of the next family member after butylene will have what chemical formula?
CH2CHCH2CH2CH3 (also written C5H10
Which of the equations below is balanced correctly? Select one:
CH4 +2O2 = CO2 + 2H2O
A solid chunk of ice or a container filled with the same mass of water in the gaseous state. Which is more ordered?
Chunk of ice
The substance most likely to be a pure element is
Copper
Reactions are most likely to occur when the chemical system
Decreases its energy but increases its entropy
Entropy is a measure of the _____________ of a system.
Disorder
The Law of Increasing Disorder
Disorder in the universe increases or stays the same anytime a process occurs.
An auto engine cannot convert all of its fuel's chemical potential energy into macroscopic kinetic energy because
Disorder would be decreased.
Why is a high temperature required for nuclear fusion to occur? Select one:
High temperatures are required to allow the nuclei to have enough kinetic energy to overcome the electromagnetic repulsion and have the strong force attraction take place.
Which of the following is a true statement about melting and boiling points in materials made of covalent molecules? Select one:
Hydrogen bonding between molecules increases melting and boiling points.
In an irreversible process, the overall disorder of the universe Select one:
Increases.
An ice cube melts in a glass of warm water. This is an example of which type of process?
Irreversible
A reversible process does what to the total disorder in the universe?
It does not change
Which of the following correctly applies the law of increasing disorder to a refrigerator?
It is true that the heat flow from the cold region to the hotter region increases order, but this is made up for by increasing the disorder of energy from another source.
How does a catalyst affect a reaction? Select one:
It lowers the activation energy
Which of the following is a correct comparison of metals and semi-conductors? Select one:
Metals' resistance increases when temperature increases while a semi-conductors resistance decreases.
Which of the following is NOT used as a technique for identifying chemical substances?
Mettler spectroscopy
Which of the following is atomic matter rather than molecular or network matter? Select one:
Neon gas
Of the following varieties of matter, the strongest bonds are found in
Network matter
Which of the following tends to have the highest melting and boiling points? Select one:
Network matter
Which of the following is a reversible process? A man diving into a pool. Water falling down Niagara Falls. A pendulum swinging. Scrambling eggs.
None of the above
Which of the following statements is true? It is not possible to convert the kinetic energy of a car into elastic energy It is not possible to convert nuclear potential energy into kinetic energy of rocks It is not possible to convert thermal energy into any other kind of energy all of the above none of the above
None of the above
Which of the following is not a compound?
Oxygen molecule
Glucose is ...
Polar and therefore sticky
A chamber with two compartments, one containing pure oxygen and the other containing pure nitrogen or the same chamber in which the two gases have been allowed to mix. Which is more ordered?
Pure oxygen
A large, solid chunk of table salt and a beaker of pure water or a solution made by mixing the salt and water together. Which is more ordered?
Pure water and pure salt
Overall disorder remains unchanged in
Reversible Process
When you compare saturated with unsaturated fatty acids containing the same number of carbon atoms, what is true? Select one:
Saturated fatty acids have more hydrogen atoms.
Locate the elements palladium (Pd, atomic #46) and nickel (Ni, atomic #28) on the periodic table. If Pd is combined with Ni, which of the following characteristics will the product show at room temperature? Select one:
Shiny, malleable solid.
Which is the best definition of an alloy?
Solid mixture of metals
The gasoline engine of an automobile is considerably less than 100% efficient. This means that not all of the energy in the gasoline is turned into kinetic energy of the car. Which of the following best explains why? Select one:
Some of the chemical potential energy in the gasoline must become ambient thermal energy if the rest is to supply the kinetic energy of the automobile. This means some energy must be wasted.
In fission, nuclei
Split such that the average mass per nucleon goes down
If analyzing a fridge in relationship to its surroundings, what would the fridge be considered?
System
Chemical bond
The attractive interaction that holds atoms together in molecules.
In carbon tetra-chloride, CCl4, what is true about the charge distribution? Select one:
The chlorine will be more negative than the carbon.
When we increase the temperature of the material
The conductivity of metals decreases whereas that of semi-conductors increases
Linear
The geometry around a carbon atom with a triple bond.
Tetrahedron
The geometry around a carbon atom with four single bonds.
Anti-bonding Orbital
The high energy orbital of the pair of MO's formed when two atomic orbitals combine.
Bonding Orbital
The low energy orbital of the pair of molecular orbitals (MO's) formed when two atomic orbitals combine.
What happens to the valence electrons as the product (MgO) is formed? Select one:
The magnesium atoms' valence electrons are effectively transferred to oxygen.
Both fission and fusion can result in a release of energy. Why? Select one:
The nuclei of atoms with a mass of about 50 have the smallest average nucleon mass and the least energy.
Equilibrium
The point in a chemical reaction in which the forward and reverse reaction rates are equal.
When you compare the mass of the products to the mass of the reactants in a fission reaction, what do you find? (note the question is asking about mass, not mass number) Select one:
The reactants have more mass
When you compare the band gap for a red and a blue LED, what is true? Select one:
The red LED has the smallest band gap.
A window air conditioner is normally placed in a window so the hot air from the back blows outside. What would happen if the air conditioner were placed in the middle of a closed room and turned on? Select one:
The room would heat up because all of the energy absorbed by the air conditioner, both thermal and electrical potential, is released back into the room as thermal energy.
A refrigerator is normally run with its door closed. What would happen if the refrigerator were placed in the middle of a closed room with its door open and turned on?
The room would heat up because all of the energy absorbed by the refrigerator, both thermal and electrical potential, is released back into the room as thermal energy
Atomic matter
The structural organization of Group 8A elements.
Extended or network substances
The structural organization of salts and metals.
Molecular substances
The structural organization of water.
Of the quantities listed, the one associated with the most disorder is
Thermal energy in a glass of water.
The purpose of the control rods in a nuclear fission reactor is Select one:
To absorb neutrons, thus limiting the number of nuclei undergoing fission.
Compounds containing transition metals are often brightly colored.
True
Gravitational potential energy is a more ordered form of energy than electrical potential energy.
True
Sodium chloride (NaCl) and Magnesium (Mg) are examples of network substances.
True
Leaving the door of the refrigerator open on a hot summer day will eventually have the effect of
Warming up the room
Which of the following is a legitimate radioactive decay because both charge and mass number are conserved?
212/84 Po = 208/82 Pb + 4/2 He
Uranium-238 alpha decays, emitting a helium-4 nucleus. What is the mass number of the product? Select one:
234
Which of the following is a correct and balanced equation showing the reaction of calcium and oxygen? (While several of the equations may be balanced, only one has the correct products and reactants as well as being correctly balanced.)
2Ca + O2 = 2CaO
In which of the following processes is the end product more ordered than the reactants? (In which process does entropy decrease.) Select one:
2H2 (gas) + O2 (gas) = 2 H2O (gas)
Beta decays occur when electrons are ejected from the nucleus electrons are absorbed in the nucleus positrons are ejected from the nucleus
All of the above
In order to get a more vigorous reaction you should increase the concentration of atoms increase the pressure increase the temperature
All of the above
Partially filled bands lead to materials that tend to be opaque be malleable conduct heat well conduct electricity well
All of the above
What do aspirin, naproxen, and ibuprofen have in common (as seen in Fig. 19.5) single bonds double bonds benzene-like rings oxygen atoms all of the above
All of the above
In the figure below, the molecular structure of a silicate mineral is shown. Where are this mineral's bonds the weakest?
Along the lines between green calcium atoms
Which of the following processes is closest to an ideal reversible process? Select one:
An ice cube floating in a glass of water at zero degrees.
The possible link between trans-fatty acids and the occurrence of health problems may be due to the fact that they...
Are straighter than cis fatty acids
In order to fill their orbitals and satisfy the octet rule, non-metals will typically
Attract extra electrons, unlike metals
When some Ca(NO3)2 dissolves in water which picture best represents what the solution looks like? (Note, the balls are not meant to indicate charge or lack of charge.)
B
A balloon filled with helium at room temperature at sea level or the same balloon at an altitude of 8000 feet where the air is colder. Which is more ordered?
Balloon at 8000 feet
Why are metals opaque? Select one:
Because metals have empty, overlapping orbitals for their electrons
When sodium (Na) and Chlorine (Cl) form table salt (NaCl) the chlorine atoms
Become negatively charged chlorine ions
Which of the following would best describe the room temperature characteristics of the magnesium oxide? Select one:
Brittle, transparent, electrically non-conducting solid.
Which of the images below has a molecular structure where the silicate ions are connected to each other without any metal atoms sandwiched between them?
C
Double bonds are found in
unsaturated fatty acids
A chemical reaction is pictured below. Which of the answers is the correct chemical formula to represent the reaction?
𝐶𝐻4 + 2𝑂2 = 𝐶𝑂2 + 2𝐻2𝑂
Which of the following fatty acids is best for human health? Select one:
Fatty acids that have one or more 'bent' cis-double bonds between carbon atoms.
Complete conversion of one form of energy to another can occur only in the direction
From higher to lower organized forms
Which of the following forms of energy is the most ordered?
Gravitational potential
Which type of energy is the most ordered?
Gravitational potential energy
Which type of energy listed below is the most ordered? Select one:
Gravitational potential energy
Which of the following is NOT why alloys are useful to us today? Alloys Select one:
Have a higher conductivity rate.
Which of the following ionic compounds is most likely to be colored (use the periodic table)?
HgS
In the equation C2H4 + 3O2 = ? CO2 + 2H2O, how many CO2 molecules are needed to balance the equation? Select one:
2
Each molecule of nitric acid has the formula HNO3. If there are 6000 oxygen atoms present and 6000 nitrogen atoms present, how many hydrogen atoms will be required to convert all of the oxygen atoms into nitric acid? Select one:
2000
What is the charge of iron (Fe) in the compound Fe2O3? Select one:
+3
The Law of Increasing Disorder places limits on the efficiency of energy conversion. Which of the following is allowed?
100% conversion of any other form of energy into ambient thermal energy.
The 2nd Law of Thermodynamics (Law of Increasing Disorder) places limits on the efficiency of energy conversion. Which of the following is allowed? Select one:
100% conversion of electricity to ambient temperature thermal energy.
The image in the problem above could be the molecular structure of which of the minerals pictured below.
A
Which of the fatty acids pictured below contains a trans bond?
A
The graphs below show energy as a function of time for several different reactions. Which of the reactions shown below would end up absorbing energy from the surroundings?
A (does not fall below the line)
Two or more different elements that are chemically combined are always
A compound
Irreversible Process
A process which goes in only one direction; its effects cannot be undone. Most processes which occur in nature are this way.
Reversible Process
A process which naturally occurs equally well forward or backwards.
Entropy
A quantitative measure of disorder. It increases as the disorder increases.
System
A small piece of the world around which we mentally draw a box and upon which we focus our attention.
Which of the following is a mass spectrum for propylene, C3H6?
D
In order for a chemical reaction to occur: Select one:
Entropy must increase as a result of the reaction.
Surroundings
Everything outside what we have defined to be the system.
