unit 3 physical science

In the equation C2H4+3O2=___CO2+2H2O, how much CO2 molecules are needed to balance the equation? A. 2 B. 3 C. 4 D. 5

A. 2

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? A. balloon at 8000 feet B. balloon at sea level

A. balloon at 8000 feet

In an irreversible process, the overall disorder of the universe: A. is conserved B. decreases C. increases D. is zero E. becomes infinite

C. increases

An ice cube melts in a glass of warm water. This is an example of which type of process? A. reversible B. impossible C. irreversible

C. irreversible

An auto engine cannot convert all of its fuel's chemical potential energy into macroscopic kinetic energy because A. energy would not be conserved B. energy would be conserved C. mass would not be conserved D. disorder would be decreased

D. Disorder would be decreased

How does a catalyst affect a reaction? A. it raises the activation entropy B. it changes anti bonding orbitals into bonding orbitals C. it lowers the band gap D. it lowers the activation energy E. it increases the energy of the transition state

D. it lowers the activation energy

A very fast reaction has a very high activation energy. T or F?

False

Compositions of alloys are generally fixed in simple ratios. T o F?

False

Metals have higher ionization energies than non-metals do. T o F?

False

Molecular orbitals are the same shape as atomic orbitals. T o F?

False

which of the following is correct comparison of metals and semi-conductors? a. metals have a larger band gap than semi-conductors b. metals' resistance increases when temperature increases while a semi conductors resistance decreases c. semi-conductos molecular orbitals overlap while metals do not d. metals have more valence electrons than semi-conductors e. metals have larger electrical resistance than semi-conductors

b. metals resistance increases when temperature increases while a semi-conductors resistance decreases

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? increases in energy decreases in energy doesnt change

increases in energy

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.

Which of the following pairs of metal is most likely to form alloys of all compositions? A. Ba and Ga B. Sn and Pb C. Li and Bi

B. Sn and Pb

Which of the following is the best description of activation energy? A. The energy at which the forward and reverse reaction rates are equal B. the energy that must be put into a system before a reaction can take place C. the energy that is released when a molecular orbital forms D. the energy that must be taken out of a system before a reaction can take place

B. The energy that must be put into a system before a reaction can take place

In order for a chemical reaction to occur: A. energy must decrease as a result of the reaction B. entropy must increase as a result of the reaction C. energy and entropy must both increase D. energy and entropy must both decrease E. energy must decrease and entropy must increase

B. entropy must increase as a result of the reaction

Which of the following forms of energy is the most ordered? A. thermal B. gravitational potential C. power D. nuclear E. chemical

B. gravitational potential

A reversible process does what to the total disorder in the universe? A. it decreases B. it does not change C. it increases

B. it does not change

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. salt water solution B. pure water and pure salt

B. pure water and pure salt

Which of the following pairs is most likely to form alloys of all proportions? A. Cs and In B. Pb and K C. Pt and Au

C. Pt and Au

If analyzing a fridge in relationship to its surroundings, what would the fridge be considered? A. entropy B. surroundings C. system D. both b and c

C. System

In the chemical equation C6H12O6+3O2=3CO2+6H2O, how many oxygen atoms are on the right side of the equation? A.3 B. 7 C.8 D. 12

D.12

A refrigerator causes a cool place to become colder, but at the same time heats up a warmer space. A fridge is normally run with its doors closed. What would happen if the fridge was 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 fridge, both thermal and electrical potential, is released back into the room as thermal energy.

Energy and entropy are both involved in chemical reactions. T o F?

True

Gravitational potential energy is a more ordered form of energy than electrical potential energy. T or F?

True

Light can only be seen through metal that is so thin it is only a few atoms thick. T o F?

True

Metals do not have a band gap. T o F?

True

Metals do not let light through. T o F?

True

Metals have a greater tendency than non-metals to lose electrons. T o F?

True

Overall disorder remains unchanged in

reversible processes

Which of the following is NOT why alloys are useful to us today? A. Alloys have lower melting temperatures B. Alloys have a higher conductivity C.Alloys are less malleable D. Alloys reduce weight in objects

B. Alloys have a higher conductivity

Which type of energy is the most ordered? A. nuclear potential energy B. gravitational potential energy C. thermal energy D. chemical potential energy

B. gravitational potential energy

Which of the equations below is balanced correctly? Mg+N2=MgN3 2P2+02=P2O5 CH4+202=CO2+2H2O 2Zn+O2=ZnO 2C+O2=2CO2

CH4+2O2=CO2+2H20

Of the quantities listed, the one associated with the most disorder is A. Chemical potential energy B. gravitational potential energy C. macroscopic kinetic energy D. nuclear potential energy E. thermal energy in a glass of water

E. thermal energy in a glass of water

A salt shaker and a pepper shaker get knocked off the table and spill on the floor. If you collected every last grain of salt and pepper and separated them back into their shakes this can be considered a reversible process. T o F?

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. T or F?

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. T o F?

False

Irreversible processes are always spontaneous and occur on their own without any intervention. T or F?

False

Metals conduct better at higher temperature. T o F?

False

Often alloys are better conductors than either of the metals, in their pure from, that make up the alloy. T o F?

False

The energies of the orbitals that form when metals interact are very widely spaced in energy. T o F?

False

The probability waves(orbital) that describe the possible locations for an electron in a molecule are exactly the same as those for an electron in an isolated atom. T o F?

False

an increase in temperature also means that disorder of a system increases. T or F?

False

A catalyst is a chemical that is present at the beginning of a reaction but not at the end. T of F?

False

Entropy is the measure of ________ in a system.

disorder

A reaction usually goes faster at higher temperatures. T of F?

True

An energetically favorable reaction gives off heat. T of F?

True

Bonding MOs have electron energies that are lower than electron energies from unbound valence electrons. T o F?

True

Compounds between two different metals are called: alloys fusion metallic bonds

alloys

The law of increasing disorder places limits on the efficiency of energy conversion. Which of the following is allowed? A. 100% conversion of any other form of energy into ambient thermal energy B. 100% conversion of nuclear potential energy to kinetic energy C. 100% conversion of thermal energy to kinetic energy D. 100% conversion of electricity to gravitational potential energy E. 100% conversion of ambient temperature thermal energy to chemical potential energy

A. 100% conversion of any other form of energy into ambient thermal energy

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? a. non-conducting, transparent solid b. shiny, malleable solid c. transparent gas d. brittle, opaque gas e. opaque gas

b. shiny, malleable solid

The 2nd law of thermodynamics places limits on the efficiency of energy conversion. Which of the following is allowed?

100% conversion of electricity to ambient temperature thermal energy

Which of the following equations is NOT balanced? 2C + 02=2CO H2+F2=2HF Mg+F2=MgF2 2H202=2H20+02 2Fe3O4=3Fe2O3+O2 4Al+3O2=2aL2O3

2Fe3O4=3Fe2O3+O2

In the upper atmosphere(also known as the ozone hole) as a catalyst. Cl may A. be lowering the activation energy of some reaction involving ozone B. be consumed in the reaction C. cause bonds to become weakened D. a and c E. a,b, and c

A. be lowering the activation energy of some reaction involving ozone.

A solid chunk of ice or a container filled with the same mass of water in the gaseous state. Which is more ordered? A. chunk of ice B. water in the gaseous state

A. chunk of ice

Compare conversion of one form of energy to another can occur only in the direction A. from higher to lower organized forms B. from lower to higher organized forms

A. from higher to lower organized forms

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?) A. in between the two atoms B. The density is evenly distributed around both atoms C. Around the outside of two atoms

A. in between the two atoms

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? A. pure oxygen B. the mixed chamber

A. pure oxygen

How do semiconductors change with increasing temperatures? A. when you heat them up, semiconductors act more like metals B. when you heat them up, semiconductors become better insulators. C. when you heat them up, semiconductors become more transparent.

A. when you heat them up, semiconductors act more like metals.

Which of the following is a reversible process? A.A man diving into a pool B. Water falling down Niagra Falls C. Scrambling eggs D. A pendulum swinging E. None of the above

E. None of the above

Which of the following processes is closest to an ideal reversible process? A. A falling golf ball falls into the mud and sticks there B. water evaporates from a glass sitting on the kitchen table C. A book sliding on a horizontal table comes to rest because of friction D. A ripe peach rotting E. An ice cube changes shapes while floating in a glass of water

E. an ice cube changes shapes while floating in a glass of water

Which of the following processes is closest to an ideal reversible process? A. two cars colliding B. Using a toaster to make toast C. a pendulum swinging D. a ripe peach rotting E. an ice cube floating in a glass of water at zero degrees

E. an ice cube floating in a glass of water at zero degrees

For an alloy to form, the atoms must be different sizes. T o F?

False

a metal can best be described as which of the following? a. network solid consisting of individual negatively charged atoms b. a network solid consisting of positively charged and negatively charged ions c. a molecular solid consisting of charged atoms d. an ionic solid consisting of covalently bonded atoms e. a network solid consisting of positively charged atoms in a sea of electrons

e. a network solid consisting of positively charged atoms in a sea of electrons

Electrons in a bonding molecular orbital are most likely to be found between the nuclei in a molecule. T o F?

True