Phys Midterm Questions
from higher to lower organized forms
Complete conversion of one form of energy to another can occur only in the direction
false
Compositions of alloys are generally fixed in simple ratios.
alloys
Compounds between two different metals are called
True
Compounds containing transition metals are often brightly colored.
false
Covalent molecules do not have well-defined shapes.
false
For an alloy to form, the atoms must be different sizes.
(A brittle, transparent solid with a very high melting point. A shiny, malleable solid with a very high melting point. ) A non-conducting material with low melting and boiling points, likely liquid or gas at room temperature. (A brittle, opaque solid with a very high melting point. A non-conducting solid at room temperature that will conduct if melted or dissolved.)
If carbon is combined with oxygen, it forms a new molecular material. Which of the following would best describe the characteristics of the material formed?
entropy must increase as a result of the reaction
In order for a chemical reaction to occur:
false
A catalyst is a chemical that is present at the beginning of a reaction but not at the end.
Pure oxygen
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 water and pure salt
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?
(A network solid consisting of individual negatively charged atoms A network solid consisting of positively-charged and negatively-charged ions A molecular solid consisting of charged atoms An ionic solid consisting of covalently-bonded atoms) A network solid consisting of positively charged atoms in a sea of electrons
A metal can best be described as which of the following?
true
A reaction usually goes faster at higher temperatures.
It does not change
A reversible process does what to the total disorder in the universe?
The ions will arrange themselves in the most energetically favorable arrangements with ions of one charge surrounded by ions of the opposite charge.
Aluminum chloride is an ionic compound with a formula of AlCl \ 3. Which of the following statements is true about the compound?
100% conversion of electricity to ambient temperature 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?
100% conversion of any other form of energy into ambient thermal energy. (100% conversion of nuclear potential energy to kinetic energy. 100% conversion of thermal energy to kinetic energy. 100% conversion of electricity to gravitational potential energy. 100% conversion of ambient temperature thermal energy to chemical potential energy.)
The Law of Increasing Disorder places limits on the efficiency of energy conversion. Which of the following is allowed?
K and Br valence electrons experience a weaker attraction for their nucleus because they are farther from the nucleus.
The atomic orbitals for potassium (K) and bromine (Br) are similar to those for sodium and chlorine. However they differ in that the potassium and bromine atomic orbitals are higher in energy than their counterparts. Why is this?
NaCl
The correct formula for sodium chloride is:
false
The energies of the orbitals that form when metals interact are very widely spaced in energy.
false
The probability waves (orbitals) that describe the possible locations for an electron in a molecule are exactly the same as those for an electron in an isolated atom.
a compound
Two or more different elements that are chemically combined are always
They would dissolve poorly or not at all because they are not polar.
What best describes how the carbon dioxide molecules would behave if mixed with water?
Chemical potential energy is converted into thermal energy resulting in an increase in entropy.
What happens to the entropy of the universe as the products are formed in an exothermic chemical reaction?
The metal atoms valence electrons are given to the non-metal.
What happens to the valence electrons as an ionic compound is formed?
they typically end up with less energy
What happens to the valence electrons when an ionic compound is formed?
solid mixture of metals
Which is the best definition of an alloy?
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.
Which of the following correctly applies the law of increasing disorder to a refrigerator?
(Thermal) Gravitational potential (power Nuclear Chemical)
Which of the following forms of energy is the most ordered?
Mettler spectroscopy (Crystallography Electronic spectroscopy Mass spectroscopy Vibrational spectroscopy)
Which of the following is NOT used as a technique for identifying chemical substances?
(Metals have a larger band gap than semi-conductors.) Metals' resistance increases when temperature increases while a semi-conductors resistance decreases. (Semi-conductors' molecular orbitals overlap while metals' don't. Metals have more valence electrons than semi-conductors. Metals have larger electrical resistance than semi-conductors.)
Which of the following is a correct comparison of metals and semi-conductors?
(A man diving into a pool. Water falling down Niagara Falls. A pendulum swinging in a frictionless environment. Scrambling eggs.) None of the above.
Which of the following is a reversible process?
(Molecules that contain double bonds melt and boil at higher temperatures because the bonds are stronger. Molecules that contain triple bonds are the most likely to be gases at room temperature. Molecules that are polar have lower melting and boiling points than non-polar molecules. ) Hydrogen bonding between molecules increases melting and boiling points. (Van der Waals (dispersion) forces lower melting and boiling points.)
Which of the following is a true statement about melting and boiling points in materials made of covalent molecules?
Neon gas (water magnesium chloride silver white gold)
Which of the following is atomic matter rather than molecular or network matter?
(sulfur dioxide) (nitrous oxide) (water molecule) oxygen molecule (rust)
Which of the following is not a compound?
(The energy at which the forward and reverse reaction rates are equal.) The energy that must be put into a system before a reaction can take place. (The energy that is released when a molecular orbital forms.) (The energy that must be taken out of a system before a reaction can take place)
Which of the following is the best description of activation energy?
(Ba and Ga) Sn and Pb (Li and Bi)
Which of the following pairs of metal is most likely to form alloys of all compositions?
(Cs and In) (Pb and K) Pt and Au
Which of the following pairs of metals is most likely to form alloys of all proportions?
(A falling golf ball falls into the mud and sticks there. Water evaporates from a glass sitting on the kitchen table. A book sliding on a horizontal table comes to rest because of friction. A ripe peach rotting.) An ice cube changes shape while floating in a glass of water at 0 degrees C.
Which of the following processes is closest to an ideal reversible process?
(Two cars colliding. Using a toaster to make toast. A pendulum swinging. A ripe peach rotting.) An ice cube floating in a glass of water at zero degrees.
Which of the following processes is closest to an ideal reversible process?
(Atomic matter) (molecular matter) network matter
Which of the following tends to have the highest melting and boiling points?
(The elements listed are very unlikely to react with one another. Electrically conducting alloy. Transparent gas. A malleable solid.) Brittle, non-conducting solid with high melting points.
Which of the following would best describe the room temperature characteristics of ionic substance?
(The elements listed are very unlikely to react with one another. Electrically conducting alloy. Transparent gas. A malleable solid.) Brittle, transparent, electrically non-conducting solid.
Which of the following would best describe the room temperature characteristics of the substance that results from the reaction of potassium and bromine?
covalent bonding
Which type of bonding involves the sharing of electrons?
(Nuclear potential energy) Gravitational potential energy (Thermal energy Chemical potential energy)
Which type of energy is the most ordered?
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.
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?
The number of electrons gained or lost when an ionic bond is formed
The oxidation state of an atom is determined by
True
Sodium chloride (NaCl) and Magnesium (Mg) are examples of network substances.
False
A salt shaker and a pepper shaker get knocked off the table and spill onto the floor. If you collected every last grain of salt and pepper and separated them back into their shakers this can be considered a reversible process.
chunk of ice
A solid chunk of ice or a container filled with the same mass of water in the gaseous state. Which is more ordered?
false
A very fast reaction has a very high activation energy.
true
Bonding MOs have electron energies that are lower than electron energies for unbound valence electrons.
Balloon at 8000 feet
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?
true
A salt is electrically neutral.
(energy would not be conserved. energy would be conserved. mass would not be conserved.) disorder would be decreased.
An auto engine cannot convert all of its fuel's chemical potential energy into macroscopic kinetic energy because
true
An energetically favorable reaction gives off heat.
Irreversible
An ice cube melts in a glass of warm water. This is an example of which type of process?
False
An increase in temperature also means that disorder increases.
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.
An refrigerator causes a cool place (the inside) to become colder, but at the same time heats up a warmer space. (A refrigerator blows hot air out the back into the room.) 12. 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?
2000
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?
true
Electrons in a bonding molecular orbital are most likely to be found between the nuclei in a molecule.
false
Electrons like to go to the highest energy condition available to them.
true
Energy and entropy are both involved in chemical reactions.
disorder
Entropy is a measure of the _____________ of a system.
(air.) (milk.) (carbon dioxide.) (wood.) copper
The substance most likely to be a pure element is
false
The triple covalent bond of carbon monoxide (CO) is a type of weak chemical interaction.
It increases in energy
If a certain LED (doped semi-conductor) is cooled in liquid nitrogen, the color moves to a higher frequency. What happens to the band gap?
System
If analyzing a fridge in relationship to its surroundings, what would the fridge be considered?
covalent
If carbon is combined with oxygen, it forms a new molecular material. What type of bond would exist between the carbon and the oxygen?
In between the two atoms (The density is evenly distributed around both atoms, Around the outside of the two atoms)
In a bonding orbital between two atoms, where is the electron density the highest? (Where do you have the highest probability of detecting an electron?)
false
In a chemical formula, subscripts are placed to the left of the chemical symbol to indicate the number of that type of atoms in a molecule.
Increases
In an irreversible process, the overall disorder of the universe
False
In the future, engineers will be able to design a car that is turns 100% of the energy in the gasoline into kinetic energy.
non-metal
Ionic compounds are formed between a metal and a
false
Ionic compounds have extremely low melting temperatures.
False
Irreversible processes are always spontaneous and occur on their own without any intervention.
true
Light can only be seen through metal that is so thin it is only a few atoms thick.
Shiny, malleable solid
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?
false
Mass spectrometry provides information about the energy associated with motions within molecules.
false
Metal and non-metal substances combine to form covalent compounds
false
Metals conduct better at higher temperatures.
true
Metals do not have a band gap.
true
Metals do not let light through.
true
Metals easily lose electrons.
true
Metals have a greater tendency than non-metals do lose electrons.
false
Metals have higher ionization energies than non-metals do.
false
Molecular orbitals are the same shape as atomic orbitals.
False
Molecular substances melt at very high temperatures
true
Molecules are only formed by covalent bonds.
true
Molten salts are ionic conductors.
(chemical potential energy. gravitational potential energy. macroscopic kinetic energy. nuclear potential energy.) thermal energy in a glass of water
Of the quantities listed, the one associated with the most disorder is
false
Often alloys are better conductors than either of the metals, in their pure form, that make up the alloy.
Reversible processes
Overall disorder remains unchanged in
false
Salts can easily be flattened or reshaped.
true
Semiconductors conduct better at higher temperatures.
False
From our current understanding, sometime in the future engineers will design a car that is completely efficient, i.e., a car that creates no additional disorder in the universe.
True
Gravitational potential energy is a more ordered form of energy than electrical potential energy.
When you heat them up, semiconductors act more like metals
How do semiconductors change with increasing temperatures?
It lowers the activation energy
How does a catalyst affect a reaction?
2
How many more electrons does unbound oxygen need to fill its 2nd shell? (You may find it helpful to draw the energy well on scratch paper.)