Question 1

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?

Accepted Answer

By connecting iron with a wire to a piece of metal like copper, a galvanic cell is formed. This results in the reduction of copper, which acts as a cathode, and the oxidation of iron, which acts as an anode. This leads to an increased rate of corrosion for the iron.

Question 2

One of the products of combustion is water. Why doesn't this water extinguish the combustion?

Accepted Answer

The water produced during combustion is in the form of steam or water vapor, which is in the gaseous phase. This means it doesn't stay in contact with the fire to extinguish it but instead floats away.

Question 3

Water is 88.88 percent oxygen by mass. Oxygen is exactly what a fire needs to grow brighter and stronger. So why doesn't a fire grow brighter and stronger when water is added to it?

Accepted Answer

The answer of Water is 88.88 percent oxygen by mass....

Question 4

Why might coating a metal with another metal that is harder to oxidize prevent the first metal from being oxidized?

Accepted Answer

Coating a metal with another metal that is harder to oxidize can protect the metal from being oxidized by preventing moisture and oxygen from coming into contact with the metal. This is because the metal that is coated is protected from moisture and oxygen, so it doesn't react.

Question 5

Why might coating a metal with another metal that is easier to oxidize prevent the first metal from being oxidized?

Accepted Answer

The answer of Why might coating a metal with another...

Question 6

Upon entering the body, are drugs gradually oxidized or reduced?

Accepted Answer

The answer of Upon entering the body, are drugs gradually...

Question 7

The oxidation of iron to rust is a problem structural engineers need to be concerned about, but the oxidation of aluminum to aluminum oxide is not. Why?

Accepted Answer

Unlike rust, which flakes off and exposes more iron to oxidation, aluminum oxide adheres to the aluminum surface and forms a barrier that prevents further corrosion. This protective layer makes the oxidation of aluminum a much smaller concern for structural engineers compared to the oxidation of iron.

Question 8

Why are combustion reactions generally exothermic?

Accepted Answer

The answer of Why are combustion reactions generally exothermic?
...

Question 9

Aluminum metal undergoes the same basic corrosion process that iron does yet it does not decompose as rapidly. Why?

Accepted Answer

The aluminum oxide formed on the surface of aluminum does not flake off like rust does on iron, but instead adheres to the surface and acts as a protective layer. This helps to slow down the decomposition of the metal.

Question 10

Upon combustion, about how many grams of water vapor are produced from every 16 grams of methane,  ?  + 2  →  + 2  O

Accepted Answer

The answer of Upon combustion, about how many grams of...

Question 11

Copper atoms have a greater tendency to be reduced than iron atoms do. Was this good news or bad news for the Statue of Liberty, whose copper exterior was originally held together by steel rivets?

Accepted Answer

Copper atoms have a greater tendency to be reduced than iron atoms, which means that in the presence of an electrolyte like saltwater or acid rain, electrons will preferentially flow from the iron to the copper and then onto oxygen. This causes corrosion around the interface of these two metals, which is bad news for the Statue of Liberty whose copper exterior is held together by steel rivets.

Question 12

A chemical equation for the combustion of propane, C₃H₈, is shown below. Through this reaction is the carbon oxidized or reduced? + 5 → 3 + 4 O

Accepted Answer

In the combustion of propane, the carbon is oxidized as it gains oxygen from the oxygen molecules in the air.

Question 13

Rust has a tendency to form when iron in contact with water reacts according to the following reaction: 4 Fe + 3 O₂ → 2 Fe₂O₃ _{What is happening at the anodic region?}

Accepted Answer

In the rusting of iron reaction, Iron is being oxidized at the anodic region. This is evident from the fact that the oxidation state of iron increases from 0 to +2, indicating that it has lost electrons, which is a characteristic of oxidation.

Question 14

Why is the air over an open flame always moist?

Accepted Answer

One of the products of combustion is water vapor, which adds moisture to the air above the flame.

Question 15

How does connecting a metal like iron with a wire to a metal that is easier to oxidize like zinc help prevent corrosion of the iron?

Accepted Answer

Connecting a metal like iron with a wire to a metal that is easier to oxidize like zinc helps prevent corrosion of the iron by causing the other metal (zinc) to oxidize instead. The electrons travel from the zinc to the iron, keeping the iron from undergoing oxidation. This process is known as sacrificial protection or cathodic protection.

Question 16

How many electrons are transferred from iron atoms to oxygen atoms in the formation of two units of iron hydroxide, Fe  ?

Accepted Answer

The answer of How many electrons are transferred from iron...

Question 17

Why is the formation of iron hydroxide, Fe  , from  and O  not considered an oxidation-reduction reaction?

Accepted Answer

In an oxidation-reduction reaction, one reactant is oxidized (loses electrons) and another reactant is reduced (gains electrons). However, in the formation of iron hydroxide, there is no transfer of electrons between the reactants (iron oxide and oxygen). Therefore, this reaction is not considered an oxidation-reduction reaction. Additionally, choice D is incorrect as iron can indeed be oxidized or reduced in other reactions.

Question 18

Iron atoms have a greater tendency to oxidize than do copper atoms. Is this good news or bad news for a home in which much of the plumbing consists of iron and copper pipes connected together? Explain.

Accepted Answer

The greater tendency of iron atoms to oxidize means that they are more likely to lose electrons to the copper atoms in the pipes, which can then pass those electrons onto oxygen atoms in contact with the surface of the pipes. This can lead to corrosion and eventual failure of the plumbing system.

Quiz 11: Oxidations and Reductions Charge the World