CHEM 110 Chapter 8
About ______ of all the electricity in the United States is used to convert aluminum oxide to the aluminum metal we use for pots, foil, and cans
1%
Oxidation, or combustion, of these fossil fuels currently supplies about _______ of the energy that turns the wheels of civilization
86%
What is the source of most nitrogen fertilizers in modern agriculture?
ammonia
In the ________________ volcano, NH4+ is oxidized and Cr2O72- is reduced
ammonium dichromate
What is an inexpensive and effective explosive, widely used for mining salt, coal, and other minerals?
ammonium nitrate fixed with fuel oil
The electrode where oxidation occurs is called the ?
anode
The familiar dry cell is used in flashlights and some small portable devices. It has a cylindrical zinc case that acts as the _________
anode
Some carbon monoxide detectors use an electrochemical cell in which carbon monoxide is oxidized to carbon oxides at the _______, and oxygen is consumed at the ________
anode, cathode
What are reducing agents found in foods?
antioxidants
What are generally best classified as oxidizing agents?
antiseptics
Oxygen occurs as 02 molecules in the _______ (the gaseous mass surrounding Earth)
atmosphere
As time goes by, the copper bar slowly ___________ and the silver bar gets _______
disappears, bigger
Highly diluted solutions of potassium permanganate are pale pink and are used in developing countries to ?
disinfect foods
The flow of electrons constitutes an _____________, and it can be used to run a motor or light a lamp
electric current
Oxidation-reduction reactions in which electrons are transferred from one substance to another can be used to produce ?
electricity
What is a device that converts chemical energy into electrical energy?
electrochemical cell
The charging reaction of the lead storage cell is one type of ?
electrolysis
An electric current in a wire is simply a flow of ?
electrons
If we place the reactants in separate compartments and connect them with a wire, the _________ will flow through the wire to get from the copper metal to the silver ions
electrons
Not everything that oxygen does is desirable. In addition to causing corrosion, it promotes _____________ and ___________
food spoilage, wood decay
The substance undergoing oxidation serves as the ?
reducing agent
A decrease in oxidation number means a gain of electrons and it therefore ?
reduction
Reducing agents cause ?
reduction
What is the gain of electrons?
reduction
What is the gain of hydrogen?
reduction
What is the loss of oxygen?
reduction
Most metals occur in nature as ?
compounds
A major advantage of lead storage batteries is that they are ?
rechargeable
Oxygen boils at ?
-183 C
Argon boils at ?
-186 C
Nitrogen boils at ?
-196 C
Roughly ______ of all iron and steel produced each year is used to replace corroded items
20%
The air we breathe is composed of approximately ______ of oxygen and ______ of nitrogen (by volume)
20%, 80%
Approximately ______ of the earth's crust is composed of oxygen
50%
The human body is approximately _______% water
65
Swimming pools are usually maintained at pH _______ - _______
7.2, 7.8
In fact, the universe is about ______% by mass H, ______% He, and _____% O
72, 26, 1
The blue solution becomes darker blue as Cu atoms are converted to _______ ions
Cu2+
What is more reactive than iron?
aluminum
What is protected from rusting by a thin layer or aluminum chloride?
aluminum
Instead of being porous and flaky like iron oxide, however, _____________ is hard and tough and adheres strongly to the surface of the metal
aluminum oxide
Swimming pools are often chlorinated with ?
calcium hypochlorite
Human cells obtain energy by oxidizing ?
carbohydrates
What increases the rate of a chemical reaction by lowering the activation energy?
catalysts
A carbon rod in the center of the dry cell is the ?
cathode
The electrode where reduction occurs is the ?
cathode
We obtain energy for all our physical and mental activities by metabolizing food in a process called ?
cellular respiration
A good example of a disinfectant is ?
chlorine
In the electrochemical cell, there are two separate compartments. One contains _____________ in a blue solution of copper (II) sulfate, and the other contains ____________ in a colorless solution of silver nitrate
copper metal, silver metal
Much current battery technology involves the use of lithium, which has an extraordinarily low _________ and provides a higher voltage than other metals
density
One of the compounds that potassium dichromate oxidizes is ?
ethyl alcohol
A battery in which a fuel is oxidized at the anode and oxygen is reduced at the cathode is a ?
fuel cell
Unlike oxygen, _________ is rarely found as a free, uncombined element on Earth
hydrogen
What is an especially vital element because it and oxygen are the components of water?
hydrogen
What is used mainly to make ammonia and methanol?
hydrogen
__________ is a colorless, odorless gas and the lightest of all substances. Its density is only one-fourteenth that of air, and for this reason it was once used in lighter-than-air craft, such as zeppelins and blimps
hydrogen
What is a common oxidizing agent that has been the advantage of being converted to water in most reactions?
hydrogen peroxide
In the _________, (the oceans, seas, rivers, and lakes), oxygen is combined with hydrogen in water
hydrosphere
The actual disinfecting agent is ?
hypochlorous acid
What is used as an antiseptic, either in an alcoholic solution or in Lugol's iodine solution?
iodine
What undergoes an undesirable oxidation-reduction (redox) reaction in the presence of air and water?
iron
In moist air, iron is oxidized, particularly at a nick or scratch. As iron is oxidized, oxygen is reduced. The net result, initially, is the formation of insoluble ___________, which appears dark green or black
iron (II) hydroxide
Iron (II) hydroxide is usually further oxidized to ?
iron (III) hydroxide
Perhaps the most important oxidation-reduction processes are the ones that maintain _______ on this planet
life
In the ________, (the outer solid portion of the Earth's crust), oxygen is combined with silicon (sand is SiO2), aluminum (in clays), and other elements
lithosphere
Disinfectants and antiseptics are alike in that both are materials used to destroy microorganisms (that is, they are germicidal), but antiseptics are applied mainly to __________ and disinfectants to ___________
living tissue, nonliving things
____________ (CH3OH), when passed over hot copper gauze, forms formaldehyde and hydrogen gas
methyl alcohol
Oxygen reacts with many compounds, oxidizing ___________ of the elements in the compound
one or more
An oxidizing agent sometimes used in the laboratory is potassium dichromate. It is an __________ substance that turns __________ when it is reduced to chromium (III) compounds
orange, green
An increase in oxidation number means a loss of electrons and is therefore ?
oxidation
Oxidizing agents cause ?
oxidation
The tarnish on silver results from _______ of the silver surface by hydrogen sulfide (H2S) in the air or from food
oxidation
What is the gain of oxygen?
oxidation
What is the loss of electrons?
oxidation
What is the loss of hydrogen?
oxidation
The charge on a simple ion is often referred to as its ?
oxidation number
Every reduction reaction must be accompanied by an _______________
oxidation reaction
Each ______________ has an oxidizing agent and a reducing agent
oxidation reduction reaction
All ____________________ occur with the transfer of electrons
oxidation reduction reactions
Most chemical reactions are _____________ reactions
oxidation-reduction
We can conclude that if one substance is oxidized, the other must cause it to be ?
oxidized
The substance undergoing reduction serves as the ?
oxidizing agent
Most household bleaches act as ?
oxidizing agents
_________________ used around the home include antiseptics, disinfectants, and bleaches
oxidizing agents
The most abundant element (by mass) in the human body is ?
oxygen
What is found in most compounds that are important to living organisms?
oxygen
A layer of _____ in the upper stratosphere serves as a shield from harmful ultraviolet radiation from the sun
ozone
The carbohydrates produced by ______________ are the ultimate source of all our food because fish, fowl, and other animals eat plants or eat other animals that eat plants
photosynthesis
The only natural process that produces oxygen is ?
photosynthesis
_____________ does not just provide the food we eat, it also provides the oxygen we breathe
photosynthesis
Solutions of ________________ (KMnO4), a common laboratory oxidizing agents, are good disinfectants
potassium permanganate
In looking at oxidation-reduction reactions, we often find it convenient to focus on the role played by a particular ?
reactant
What is the process in which chemical change produces electricity?
reverse process
Dry cells and fuel cells produce electricity from chemical reactions. Sometimes, we can _______ the process. In electrolysis, electricity supplied externally causes a ____________ reaction to occur
reverse, chemical
Ozone can be extremely irritating to both plants and animals and is especially destructive to ?
rubber
Certain substances, such as _______, can interfere with the protective oxide coating on aluminum, allowing the metal to oxidize
salt
Oxidation and reduction often occur at _______ points on the metal's surface
separate
In making a black-and-white photograph, _______________ in the film is exposed to light
silver bromide
Corrosive reactions are quite ?
slow
The tarnished silver is placed in contact with aluminum metal (often in the form of foil) and covered with a hot solution of ?
sodium bicarbonate
Oxidation and reduction always occur ?
together
Electrochemical reactions are often represented as ?
two-half-reactions
Because water is 89% oxygen by mass and many other compounds in your body also contain oxygen, almost ________ of your body mass is oxygen
two-thirds
The typical reaction for the explosive reaction produces a huge ______ increase, which becomes part of the explosive force
volume