Module 10
The charge on the sulfur in the compound copper sulfide, Cu2S, is ________.
-2
Chemical equations need to be balanced not only in terms of the number of atoms, but also by the charge. In other words, just as there should be the same number of atoms before and after the arrow of an equation, there should be the same charge. What set of coefficients is necessary to balance the following chemical equation? ____ Sn2+ + ____ Ag → ____ Sn + ____ Ag⁺ 1, 1, 2, 1 1, 1, 1, 2 1, 2, 1, 2 1, 2, 2, 2
1, 2, 1, 2
In a battery, if the following oxidation-reduction reactions takes place normally: Mn2O3 + ZnO → 2 MnO2 + Zn What reaction would be taking place if you were charging the battery?
2 MnO2 + Zn → Mn2O3 + ZnO
How many electrons are gained or lost in the following half-reaction? Cl2 → 2 Cl-
2 electrons are gained
How many electrons are gained or lost in the following half-reaction? C → C4-
4 electrons are gained
Water is 88.88 percent oxygen by mass. Oxygen is exactly what a fire needs to grow brighter and stronger. Which of the following may be reasons why doesn't a fire grow brighter and stronger when water is added to it? All of the answers are correct. Oxygen in water is already "reduced" from the hydrogen atoms, so this oxygen atom no longer has a great attraction for additional electrons. The oxygen is chemically bound to hydrogen atoms and has different properties that elemental oxygen (O2). Oxygen in water is completely different from oxygen O2, which is what is required for combustion.
All of the answers are correct.
What might the relationship be between an element's electronegativity and its ability to behave as an oxidizing agent? As the electronegativity increases the ability of an element to act as an oxidizing agent decreases. As the electronegativity increases the ability of an element to act as an oxidizing agent increases. None of the answers are correct. As the electronegativity increases the ability of an element to act as an oxidizing agent stays the same.
As the electronegativity increases the ability of an element to act as an oxidizing agent increases.
A battery operates by ________. oxidation reduction Neither oxidation nor reduction. Both oxidation and reduction.
Both oxidation and reduction.
What is the primary difference between a fuel cell and a battery? Batteries can never be recharged, while fuel cells can be recharged. Fuel cells can continue to run as long as they are provided with a source of fuel; batteries run down and need to be recharged. Batteries supply electricity; fuel cells supply heat. Fuel cells oxidize to supply electricity, batteries reduce to supply electricity.
Fuel cells can continue to run as long as they are provided with a source of fuel; batteries run down and need to be recharged.
How would connecting iron with a wire to a piece of metal like copper, which undergoes reduction very easily, affect the rate at which the iron corrodes? It would increase the rate of corrosion. Rates are only affected by temperature. It would decrease the rate of corrosion. The rate would stay the same.
It would increase the rate of corrosion.
The general chemical equation for photosynthesis is shown below. Through this reaction is the carbon oxidized or reduced? How can you tell? 6 CO2 + 6 H2O → C6H12O6 + 6 O2
Reduced, since in carbon dioxide there are two oxygen atoms for every one carbon but within the product, , (glucose), there is only one oxygen for every one carbon.
In the oxidation-reduction reaction Mg(s) + Cu2+(aq) → Mg2+(aq) + Cu(s), which atom or ion is reduced? Which atom or ion is oxidized? The Cu2+ ion is reduced as it gains electrons to form copper metal, Cu. The magnesium metal, Mg, is oxidized as it loses electrons to form Mg2+. Both the Cu2+ ion and the Mg are reduced in this reaction. The Cu2+ ion is oxidized as it gains electrons from the copper metal, Cu. The magnesium metal, Mg, is reduced as it loses electrons to form Mg2+. Both the Cu2+ ion and the Mg are oxidized in this reaction.
The Cu2+ ion is reduced as it gains electrons to form copper metal, Cu. The magnesium metal, Mg, is oxidized as it loses electrons to form Mg2+.
A major source of chlorine gas, Cl2, is from the electrolysis of brine, which is concentrated salt water, At which electrode is the Cl2 formed? Neither the anode or the cathode. The anode since Cl- is being oxidized to Cl2. It could be formed at either the anode or the cathode. The cathode since Cl- is being oxidized to Cl2.
The anode since Cl- is being oxidized to Cl2.
The following set of redox reactions takes place as shown. Container A Container B Fe → Fe2+ + 2e- Cu2+ + 2e- → Cu If you had two containers filled with the ion solution described above with a wire connecting a piece of iron (in container A) and a piece of copper (in container B) and a salt-bridge connecting the two containers, which way do the positive ions in the salt-bridge flow? The ions only move in the containers they originate in. The positive ions flow back and forth between the two containers. The positive ions flow to container A. There is no flow of positive ions in the salt-bridge The positive ions flow to container B.
The positive ions flow to container B.
How does p-type silicon differ from pure silicon? There are no positive charges available. There are other elements with more valence electrons than silicon in the silicon matrix. There are other elements with less valence electrons than silicon in the silicon matrix. There are extra silicon atoms resulting in distortion of the silicon matrix.
There are other elements with less valence electrons than silicon in the silicon matrix.
The following set of redox reactions takes place as shown. Container A Container B Fe → Fe2+ + 2e- Cu2+ + 2e- → Cu If you had two containers filled with the ion solution described above with only a wire connecting a piece of iron (in container A) and a piece of copper (in container B), which way do the electrons flow?
There is no continuous flow of electrons without the presence of a salt bridge connecting the solutions in the two containers.
In the salt bridge, anions flow towards the ___________
anode
Oxidation will always occur at the _________ anode cathode
anode
Electrons will always flow from the __________ to the ____________ cathode anode
anode cathode
In a salt bridge, negative ions go to the oxidation side (__________), positive ions go to the reduction side (______________)
anode cathode
During combustion, the oxygen atoms of oxygen molecules ________.
become reduced
In the salt bridge, cations flow toward the _____________
cathode
Reduction always occurs at the____________ anode cathode
cathode
__________ __________ protecting a metal (like iron) from oxidation by placing it in electrical contact with a metal that has a greater tendency to oxidize.
cathodic protection
_________________________ is the study of the relationship between chemical reactions and electrical energy
electrochemsitry
___________ is the use of electrical energy to produce chemical change (the opposite of a voltaic cell)
electrolysis
______________ is the operation of coating one metal with another by electrolysis.
electroplating
_______ ________ is a device that converts energy of fuel to electrical energy
fuel cell
reduction= ____________ of electrons
gain
A ___________ reaction shows only the oxidation or the reduction reaction.
half
oxidation= ___________ of electrons
loss
When electrons are on the product side, they were given up or ________
lost
_______ type silicon contains extra electrons and have free negative charges
n type
Anions are ________ ions
negative
Oxidation state becomes more _____________ when it's gaining electrons.. This is called reduction/
negative
The ____________ terminal of a battery is where the electrons want to flow away from.
negative
Electrons have a negative charge so if something is gaining electrons, it will become more ___________. Which makes the oxidation state more ___________
negative negative
If something was reduced, it is the ___________ and considered as the __________ agent
oxidant oxidizing agent
The ionic state becomes more positive with _____________
oxidation
When the oxidation state becomes more positive, we know we've lost electrons and losing electrons is _____________
oxidation
If something is gaining oxygen, it is becoming ___________
oxidized
If something is losing hydrogen, its becoming ___________
oxidized
In oxidation reduction reactions- electrons flow from the reactant being ____________ to the reactant being ___________
oxidized reduced
_______ type silicon contains electron holes and any passing electron is attracted to this spot as if it were positively charged
p type
When boron is added to a layer of ultrapure silicon, the result is ________.
p-type silicon
The ___________ _____________ is the ability of light to excite electrons in an atom
photoelectric effect
_____________convert sunlight to electrical energy
photovoltaics
Cations are __________ ions
positive
Oxidation state becomes more ___________when it's losing electrons
positive
In a metal-containing compound, the metal exists as a ________.
positively charged ion
A strong oxidizing agent means its easily ____________ and likes to gain electrons
reduced
If something is gaining hydrogen, it is becoming _____________
reduced
If something is losing oxygen, it is becoming ____________
reduced
It something is a strong oxidizing agent, it wants to be__________ and wants to _____________electrons.
reduced gain
If something was oxidized, it is the ___________ and considered as the ________________ agent
reductant reducing agent
The ionic state becomes more negative with ______________
reduction
When an oxidation state goes from 0 ---> -1, this is called ______________
reduction
In a battery, the following two oxidation-reduction reactions are taking place: rxn A: Zn → Zn2+ + 2e- rxn B: 2 NH4+ + 2e- → 2 NH3 + H2 Which reaction is taking place at the anode?
rxn A
____________ _____________ allow ions (separate from species involved in the reaction) to migrate between containers so no charge builds up in either container.
salt bridge
What is the purpose of a salt-bridge? to allow ions to migrate between solutions and maintain a charge balance to allow electrons to migrate through solutions All of the answers are correct. to allow salt to form in the oxidation-reduction reactions
to allow ions to migrate between solutions and maintain a charge balance
T or F: Both Corrosion and combustion utilize oxygen.
true
T or F: Combustion is happening in our body all the time as we metabolize food. It requires oxygen to combine with the food then produces glucose which we exhale and water.
true
T or F: Electrolysis can be used to break apart water or recharge batteries or purify metals
true
T or F: In Ionic compounds, elements have oxidation states equal to their ionic charges.
true
T or F: Ionic compounds like to be neutral
true
T or F: Metals in compounds always have a positive charge
true
T or F: On the left side of the equation, the coefficients nor the subscripts make a difference when determining the oxidation numbers.
true
T or F: Only a oxidation reduction reaction if it involves the transfer of electrons.
true
T or F: The oxidizing agent is something that is getting reduced.
true
T or F: To get metal atoms from a compound with a negative charge to a atoms with no charge, you will need to do an oxidization-reduction reaction and reduce the metal
true
T or F: When electrons are on the reactant side, they are being added (gained)
true
T or F: With an ionic compound, the oxidation states are equal to the charges of the ions in those compounds
true
__________ ______ chemical reaction that produces electricity
voltaic cell
Elements that are by themselves without a charge have an oxidation state of ___________
zero
