chem 107 final

which of the following species play a role in maintaining the normal pH of seawater?

NO3-

HCO3-

SO42-

H2CO3

CO32-

HCO3-

CO32-

H2CO3

benjamin franklin fabricated the first functional battery, the voltaic pile

false

a galvanic cell is a type of electrochemical cell that converts energy released from a __________ _________ reaction into electrical energy

spontaneous chemical

a true battery is a collection of ______ cells that are wired together

galvanic

the loss of electrons

oxidation

the gain of electrons

reduction

which of the following options correctly describe a half-reaction?

- a half-reaction is an equation that represents the overall process occurring in a galvanic cell.

- the overall process occurring in a galvanic cell includes both an oxidation and a reduction reaction. The two parts are each known as half-reactions.

- a half-reaction shows the electrons gained by the reactants in a galvanic cell.

- a half-reaction shows the electrons lost by the reactants in a galvanic cell.

- the overall process occurring in a galvanic cell includes both an oxidation and a reduction reaction; the two parts are each known as half-reactions.

- a half-reaction shows the electrons gained by the reactants in a galvanic cell

- a half-reaction shows the electrons lost by the reactants in a galvanic cell

who first coined the term "battery"?

Nikola Tesla

Thomas Edison

Benjamin Franklin

Alessandro Volta

Benjamin Franklin

a(n) ______ cell converts the energy released in a spontaneous chemical reaction into electrical energy

galvanic

a true _______ is made up of several galvanic (voltaic) cells that are wired together

battery

a process in which a species loses electrons is known as ______, whereas a process in which a species gains electrons is known as ______

oxidation; reduction

which of the following options correctly describe cell voltage?

some cells can last as long as ten years

cell voltage is a function of the size of the cell

cell voltage is a function of the chemicals used to construct the battery

higher voltages are possible by connecting cells

- cell voltage is a function of the chemicals used to construct the battery

- some cells can last as long as ten years

- higher voltages are possible by connecting cells

a(n) ______ is a type of chemical equation that shows the electrons either lost or gained by the reactants

half-reaction

oxidation reaction

reduction reaction

half-reaction

rank the following common galvanic cells in order of increasing voltage, starting with the lowest voltage cell at the top of the list

Ni-Cd

alkaline

lead-acid

lithium ion

to track the transfer of electrons in both ionic and molecular substances, we assign a(n) ______ number to each element involved

this number reflects the charge the element would have if all bonds were ionic

oxidation

which of the following options correctly describe a rechargeable battery?

-the battery's lifetime is dependent on the breakdown of the separators.

-the battery's lifetime is not dependent on the generation of unwanted side-reactions.

-the battery's lifetime is dependent on the accumulation of impurities.

-both reactants and products are solids.

-both reactants and products are liquids.

-the battery's lifetime is dependent on the accumulation of impurities

- the battery's lifetime is dependent on the breakdown of the separators

- both reactants and products are solids

the voltage of a battery is affected by ______

the number of electrochemical cells wired together

its physical size

the sizes of each of the individual cells connected together

its chemical composition

-its chemical composition

-the number of electrochemical cells wired together

which of the following options correctly describe the separator in any battery?

-electrons flow from anode to cathode through the separator.

-the separator retains charge neutrality during battery operation.

-the separator in modern batteries is frequently a semipermeable membrane that allows ion flow.

-the separator is an insulator.

-the separator may be an electrolyte solution.

-the separator retains charge neutrality during battery operation

-the separator may be an electrolyte solution.

-the separator in modern batteries is frequently a semipermeable membrane that allows ion flow.

a dry cell battery

contains an electrolyte paste with just enough moisture to allow ions to flow

lead acid's typical application is

automobile batteries

alkaline's typical application is

flashlights and small appliances

lithium ion's typical application is

computers

nickel-metal hydride's (NiMH) typical application is

hybrid vehicle batteries

which of the following are important attributes for the battery of electric vehicles?

-it must have a low density (i.e., be lightweight).

-it must have a long operating range per charge.

-it must be heavy to withstand possible crashes.

-it must be fabricated with lithium.

-it must have a low density

-it must have a long operating range per charge

the oxidation state of an element ________

- reflects the way electrons are transferred during a reaction

- is determined by the way it is bonded

- reflects its charge if it is present as an ion

a battery that employs electrochemical reactions that run in both directions is

rechargeable

a device composed of electrodes immersed in electrolytes that stores electrical energy in the form of a static charge is called a(n

supercapacitor

why does a battery require a separator?

direct contact between cathode and anode causes a short circuit

which of the following will cause the capacitance of a charged-plate supercapacitor to increase?

greater separation between the charged plates.

smaller separation between the charged plates.

smaller surface area of the charged plates.

greater surface area of the charged plates.

-smaller separation between the charged plates

-greater surface area of the charged plates

batteries such as rechargeable Ni-Cd batteries are referred to as ______ cells because they contain an electrolyte that is mobilized as a paste rather than an electrolyte solution

dry

which of the following options correctly describe supercapacitors and rechargeable lithium-ion batteries?

supercapacitors are much cheaper to produce

li-ion batteries charge much more quickly than supercapacitors

supercapacitors have much higher power densities than Li-ion batteries

supercapacitors operate effectively over a wider temperature range than Li-ion batteries

-supercapacitors operate effectively over a wider temperature range than Li-ion batteries

- supercapacitors have much higher power densities than Li-ion batteries

which of the statements below are benefits of using Li-ion batteries for automotive applications

lithium metal is extremely lightweight

a battery or capacitor with a high power density ______

delivers power quickly

the __________ energy density of a battery measures stored charge in units of Wh/g. while the __________ energy density measures the stored charge in units of Wh/L

weight; volume

a vehicle that is propelled by a combination of a conventional gasoline engine and an electric motor run by batteries is a __________

hybrid electric vehicle

supercapacitors ______

store energy in the form of a static electrical charge

may release stored charge as electrical energy

are identical to batteries

consist of two electrodes immersed in an electrolyte

produce electrical power by means of a continuous, reversible electrochemical process

-may release stored charge as electrical energy

-store energy in the form of a static electrical charge

-consist of two electrodes immersed in an electrolyte

which of the following options correctly describe the power system of a hybrid electric vehicle (HEV)?

the gasoline engine assists the electric motor during normal driving.

the electric motor draws power from the nickel-metal hydride batteries to power the vehicle at low speeds.

regenerative braking is used to charge the batteries during braking and deceleration.

the electric motor draws power from the gasoline engine to power the vehicle at low speeds.

-the gasoline engine assists the electric motor during normal driving

-regenerative braking is used to charge the batteries during braking and deceleration

-the electric motor draws power from the nickel-metal hydride batteries to power the vehicle at low speeds.

the build-up of static electrical charge on a capacitor is called

capacitance

H2 burns to form

H2O only

CH4 burns to form

CO2 and H2O

which of the following represents a benefit of supercapacitors, relative to Li-ion batteries?

shorter charging time

how can hydrogen be used as a fuel?

hydrogen burns in oxygen to produce H2O and heat

the ________ density refers to the time it takes for a battery to deliver its charge. In contrast, the _________ density refers to the stored capacity of the battery

power; energy

the main disadvantage in using hydrogen as a fuel source is its _____

flammability

a hybrid electric vehicle (HEV) is propelled by

both a conventional gasoline engine and an electric motor run on batteries

a fuel cell converts

the chemical energy of a fuel directly into electricity without burning the fuel

____________ braking is used to charge the battery in a hybrid vehicle during deceleration and braking

regenerative

in both fuel cells and conventional batteries

an electrochemical reaction produces energy

which of the following options correctly describe hydrogen and methane fuels?

-H2 produces fewer pollutants than CH4 when burned

-both fuels are flammable gases

-H2 releases almost three times as much energy per gram as CH4 when burned.

which of the following options correctly describe the key features of a fuel cell?

- proton exchange membranes in a fuel cell are not permeable to H+ ions.

- H2 passes through the PEM and is oxidized to form two H+ ions.

- solid polymer electrolyte materials separate the reactants.

- the cell generates its own fuel.

- the anode in a fuel cell simply acts as a conductor and does not participate in the oxidation reaction.

-the anode in a fuel cell simply acts as a conductor and does not participate in the oxidation reaction

-H2 passes through the PEM and is oxidized to form two H+ ions

-solid polymer electrolyte materials separate the reactants.

what products are formed when hydrogen gas (H2) is burned in oxygen?

H20 and heat

a hydrogen fuel cell produces energy ______ rapidly and with ______ efficiency than the production of energy in a conventional combustion engine

less; higher

what is the major disadvantage of burning hydrogen as a source of energy?

- hydrogen is extremely flammable and can explode when mixed directly with oxygen.

- hydrogen produces a variety of pollutants when burned in oxygen.

- it requires a large amount of energy to burn hydrogen.

- hydrogen does not produce as much energy as other combustible fuels.

hydrogen is extremely flammable and can explode when mixed directly with oxygen

H2 gas can be stored using metal ______ such as LiH, which absorb H2 molecules into the spaces within their crystal structure

hydrides

a(n) ______ cell is an electrochemical cell that produces electricity by converting the chemical energy of a fuel directly into electricity without burning the fuel

fuel

which of the following products are formed during the electrolysis of water?

H2

electrical energy

O2

O3

O2 and H2

in a fuel cell, H2 is ______ to form 2H+ as it passes through the PEM. These H+ ions combine with O2 at the cathode in a ______ half-reaction to form H2O

oxidized; reduction

an electrolytic cell converts

electrical energy into chemical energy

hydrogen fuel cells are more environmentally friendly than coal-fired or nuclear power plants

true

which of the following options correctly describe environmental consequences that result from the production of batteries?

- acid rain is produced as a result of SO2 release during the metal ore refining process.

- lead-acid batteries may leak and release corrosive material into the environment.

- disposing of lead-acid batteries in a landfill contaminates the land with toxic mercury

- the mining of metal ores needed to produce batteries leaves mine tailings and other waste that must be cleaned up.

-lead-acid batteries may leak and release corrosive material into the environment

- acid rain is produced as a result of SO2 release during the metal ore refining process

- the mining of metal ores needed to produce batteries leaves mine tailings and other waste that must be cleaned up.

which of the following options correctly describe the role of metal hydrides for the storage and transportation of hydrogen gas?

- metal hydrides are selective and can separate H2 from larger molecules such as O2, CO, and CO2.

- metal hydrides store hydrogen in the form of H- ions.

- when placed under high pressure the metal hydride acts like a sponge to absorb H2 molecules.

- H2 can be released on demand by increasing the temperature or increasing the hydrogen pressure.

-metal hydrides are selective and can separate H2 from larger molecules such as O2, CO, and CO2

- when placed under high pressure the metal hydride acts like a sponge to absorb H2 molecules.

what are the two main disadvantages of the production of hydrogen from methane (CH4)?

-CO2 (a greenhouse gas) is produced in addition to hydrogen

-the process requires significant energy input.

the decomposition of water into H2 and O2 by passing an electric current through it is called

electrolysis

a(n) ______ cell is a type of electrochemical cell in which electrical energy is converted to chemical energy

electrolytic

which of the following pollutants may be released into the environment during the production or incorrect disposal of batteries?

CO2

Acid rain

Toxic metals

SO2

O3

-SO2

-toxic metals

-CO2

galvanic cells are compartments that are capable of converting the energy released form spontaneous chemical reactions into electrical energy

true

chemical energy is converted directly into electrical energy in

an automobile's engine

an electrical power plant

a galvanic cell

an electrolytic cell

a galvanic cell

batteries enable us to _____.

store electric charge in a portable way

convert solar energy into electrical energy

always stay connected to the power grid

create electrical energy

store electric charge in a portable way

why can the lead-acid batteries used in cars generate electricity for several years before running down?

a lead-acid battery is so large that it holds large quantities of the chemicals whose electrochemical interaction creates the electricity

the mechanical motion of the engine drives an alternator that generates electricity to recharge the battery

these batteries are used only to generate the electricity that makes the first spark plug "spark." Therefore, they are hardly used at all when a car is started, and never when it is driven

the electrons they generate, not the chemical components, provide almost all of the electricity

the mechanical motion of the engine drives an alternator that generates electricity to recharge the battery

which type of battery is best for use in heart (cardiac) pacemakers?

mercury

alkaline

nickel-cadmium

lithium-iodine

lithium-iodine

oxidation and reduction are processes through which __________

substances lose and gain electrons

a substance changes from one metal into another

gas molecules are converted to solid metal

electricity is created from solar energy

substances lose and gain electrons

which type of battery is widely used to store the excess energy generated by windmill farms and solar panels?

lithium ion

nickel-metal hydride

lead acid

alkaline

lead acid

in an electrochemical cell, the anode is

the material used to connect the two half cells to each other

always used up before the cathode

the electrode at which oxidation takes place

never a metal.

the electrode at which oxidation takes place

rechargeable batteries are different than standard batteries because _____

they rely on moving protons instead of moving electrons

their oxidation-reduction reactions are reversible

they can be reused indefinitely

they rely on oxidation, but not reduction

their oxidation-reduction reactions are reversible

rechargeable batteries can no longer function when

they have been recharged 10 times

changes to their surfaces prevent electrons from flowing

the temperature is too low

they are unplugged from a wall charger

changes to their surfaces prevent electrons from flowing

which type of widely used battery is not rechargeable?

zinc-manganese alkaline

nickel-cadmium (NiCad)

lithium-ion

lead-acid (storage batteries)

zinc-manganese alkaline

whenever a substance is oxidized

it is called the oxidizing agent

some other substance must be reduced

it gains electrons

hydronium ions are produced

some other substance must be reduced.

according to the USGS, how much water per day is needed by the average U.S. citizen?

> 390 L

> 100 mL

> 100 L

> 390 gal

> 390 L

what is the shape of a water molecule?

bent

which of the following options correctly describe electronegativity and its trends?

the element with the highest electronegativity is fluorine

the higher the electronegativity value of an element, the more strongly it attracts bonding electrons to itself

the highest electronegativity value for any element is 0.7

electronegativity increases going down a group in the periodic table

electronegativity increases from left to right in the periodic table

- the element with the highest electronegativity is fluorine

- the higher the electronegativity value of an element, the more strongly it attracts bonding electrons to itself

- electronegativity increases from left to right in the periodic table

if the sign δ- is used to mark an atom in a covalent bond, it means that ______

this atom has a higher electron density

this atom is less electronegative

this atom is more electronegative

this atom has a partial negative charge

this atom has a lower electron density

this atom has a higher electron density

this atom is more electronegative

this atom has a partial negative charge

approximately how much water per day is required to support the lifestyle of the average u.s. citizen, according to the u.s. geological survey?

100 gallons

in a(n) ______ bond, electrons are not shared equally but are closer to the more electronegative atom

covalent

nonpolar covalent

ionic

polar covalent

polar covalent

the ability of a covalently bonded atom to attract the shared electrons is called

electronegativeity

what is potable water?

water that can be carried easily

water that is unsafe for human use

water that is safe to drink and to cook with

water that is piped to a given location

water that is safe to drink and to cook with

approximately how many people on the earth lack access to clean drinking water?

10,000

100,000

1,000,000

2,000,000,000

2,000,000,000

fresh water found in aquifer is located

below ground

water that is safe to drink and to cook with is called ______ water

potable

which of the following options correctly describes the different sources of fresh water?

the majority of fresh water is surface water

surface water is found in lakes, streams, and rivers

the most convenient form of water is groundwater

groundwater is found in aquifers

surface water is found in lakes, streams, and rivers

groundwater is found in aquifers

according to the world health organization estimates, approximately how many infants and children die each day due to contaminated water?

> 3000

1000-2000

2000-3000

> 15,000

> 3000

an is a source of freshwater __________ located underground

aquifer

which of the following bodies of water is/are included in the natural water cycle?

permafrost

lakes

glaciers

fish tank

rivers

lakers

glaciers

rivers

which of the following options correctly describe molecular polarity?

a molecule that contains polar and nonpolar covalent bonds could be polar or nonpolar

a molecule that contains only nonpolar bonds is nonpolar

overall molecular polarity depends on the geometry of a molecule

a molecule that contains polar covalent bonds is necessarily polar

a molecule that contains polar and nonpolar covalent bonds could be polar or nonpolar

a molecule that contains only nonpolar bonds is nonpolar

overall molecular polarity depends on the geometry of a molecule

naturally occurring underground reservoirs containing fresh water are called _________

aquifers

which of the following would represent an example of a tragedy of the commons?

dumping waste into a public lake

spraying round-up herbicide on paths in your backyard

adding chlorine tablets to a private well

overfishing a lake

dumping waste into a public lake

overfishing a lake

what percentage of water on Earth is fresh water?

3%

30%

97%

68%

3%

a water ___________ is an estimate (for an individual or nation) of the amount of water required to sustain the consumption of goods and services

footprint

which of the following options correctly describe the water cycle?

the water cycle only includes water in its gaseous and liquid states

climate can affect the water cycle

a drop of water in the ocean could one day end up in a lake

the natural water cycle is not affected by human activities

climate can affect the water cycle

a drop of water in the ocean could one day end up in a lake

which of the following molecules is polar?

CO2

NH3

Br2

SiF4

NH3

normal seawater is slightly ______ with a pH of around ______

acidic; 8.2

basic; 7.0

basic; 8.2

acidic; 6.2

slightly basic with a pH of around 8.2