GCSE Chemistry - Fuel Cells #45

Summary

This video delves into the workings of fuel cells, particularly hydrogen-oxygen fuel cells, which convert chemical energy into electricity by combining hydrogen and oxygen to produce water. It explains the cell's structure, including the electrolyte, electrodes, and the flow of electrons and ions. The script clarifies the difference between the anode and cathode in fuel cells and electrolysis. It also outlines the advantages of fuel cells, such as their pollution-free operation and longevity, and the challenges like hydrogen storage and the energy required for its production.

Takeaways

• 🔋 A fuel cell is an electrochemical cell that converts chemical energy from fuel and oxygen into electrical energy.
• 💧 The hydrogen-oxygen fuel cell is the most common type, combining hydrogen and oxygen to form water while generating electricity.
• 🌐 The cell structure includes an electrolyte, electrodes (anode and cathode), and compartments for hydrogen and oxygen intake.
• ⚡ The anode oxidizes hydrogen, releasing electrons, while the cathode reduces oxygen, combining with hydrogen ions and electrons to form water.
• 🔄 The overall reaction in a fuel cell is the combination of oxygen and hydrogen to produce water, with the release of electrical energy.
• 🔌 The electrical energy is generated by the flow of electrons from the anode to the cathode through an external circuit.
• 🌿 Hydrogen-oxygen fuel cells offer an environmentally friendly alternative to fossil fuels, producing only water as a byproduct.
• 🚗 They are considered for use in vehicles to replace polluting engines and have the potential to replace power stations.
• 💨 A challenge with hydrogen is its gaseous state, requiring more space for storage compared to liquid fuels or solid batteries.
• ⚠️ Hydrogen is explosive when mixed with air, presenting safety concerns for storage and handling.
• ♻️ The production of hydrogen fuel requires energy, often derived from non-renewable sources, which can offset the environmental benefits.

Q & A

What is a fuel cell and how does it convert energy?

A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (like hydrogen) and oxygen into electrical energy, which can be used to power various devices.

What is the most common type of fuel cell?

The most common type of fuel cell is the hydrogen-oxygen fuel cell, which combines hydrogen and oxygen to produce water and generate electrical energy.

What is the role of the electrolyte in a fuel cell?

The electrolyte in a fuel cell allows ions to move through it, facilitating the flow of hydrogen ions from the anode to the cathode. Potassium hydroxide is a common type of electrolyte used.

Why are the anode and cathode in a fuel cell different from those in electrolysis?

In a fuel cell, the anode is negative and the cathode is positive, which is the opposite of electrolysis where the anode is positive and the cathode is negative. This difference is due to the direction of electron flow and the reactions occurring at each electrode.

What happens to the hydrogen when it enters the anode compartment?

When hydrogen enters the anode compartment, it is oxidized, meaning each hydrogen atom loses an electron to become a hydrogen ion, which then moves through the electrolyte to the cathode.

How do electrons move in a fuel cell, and what drives this movement?

Electrons move from the anode to the cathode through an external circuit, driven by the potential difference created by the oxidation of hydrogen and the reduction of oxygen at the electrodes.

What is the overall reaction that occurs in a hydrogen-oxygen fuel cell?

The overall reaction in a hydrogen-oxygen fuel cell is the combination of oxygen and hydrogen to form water, releasing electrical energy in the process.

Why are hydrogen-oxygen fuel cells considered environmentally friendly?

Hydrogen-oxygen fuel cells are considered environmentally friendly because they only require hydrogen and oxygen, which are abundant, and their only waste product is water, with no carbon dioxide or other pollutants.

What are some challenges associated with using hydrogen as a fuel?

Challenges with hydrogen as a fuel include its gaseous state, which requires more space for storage compared to fossil fuels or batteries, its explosiveness when mixed with air, and the energy required to produce hydrogen, often derived from non-renewable sources like fossil fuels.

How do fuel cells compare to batteries in terms of longevity and disposal?

Fuel cells generally last longer than batteries due to their relatively simple design. They are also less polluting to dispose of, as they do not contain the harmful chemicals that some batteries do.

What is the potential application of hydrogen-oxygen fuel cells in vehicles?

Hydrogen-oxygen fuel cells can potentially replace fossil fuel engines and batteries in vehicles, offering a cleaner alternative for powering transportation without producing carbon dioxide or other pollutants.

Outlines

00:00

🔋 Understanding Hydrogen-Oxygen Fuel Cells

This paragraph introduces the concept of fuel cells, specifically hydrogen-oxygen fuel cells, which convert chemical energy from hydrogen and oxygen into electrical energy. The structure of these cells includes an electrolyte, typically potassium hydroxide, and electrodes—negative anode and positive cathode—made of porous carbon containing catalysts. The process begins with hydrogen oxidation at the anode, releasing electrons that travel through a wire to the cathode, while hydrogen ions move through the electrolyte. At the cathode, oxygen, hydrogen ions, and electrons combine to form water, releasing heat. The movement of electrons generates electricity, which can power various devices. The paragraph clarifies the difference between fuel cells and electrolysis in terms of electrode polarity and emphasizes the importance of understanding the structure and function of fuel cells.

05:03

🚀 Pros and Cons of Hydrogen-Oxygen Fuel Cells

The second paragraph discusses the practical application and implications of hydrogen-oxygen fuel cells. It highlights the process of oxidation within the cell, where hydrogen loses electrons, creating a potential difference that drives electron flow and generates electricity. The benefits of these fuel cells include their use of abundant hydrogen and oxygen, the lack of carbon dioxide or other pollutant emissions, and their relatively simple construction leading to longer lifespans and less environmental impact upon disposal. However, challenges such as hydrogen's gaseous state, which requires more space for storage, its explosiveness when mixed with air, and the energy required to produce hydrogen from fossil fuels are also acknowledged. The paragraph concludes with a call to action for viewers to engage with the content, suggesting the broader implications of adopting fuel cell technology.

Keywords

💡Fuel cell

A fuel cell is an electrochemical cell that converts chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. In the context of the video, the focus is on hydrogen-oxygen fuel cells, which are a common type that combines hydrogen and oxygen to produce water and electrical energy. The video explains that these cells have a complex setup involving an electrolyte, electrodes, and a catalyst to facilitate the reaction, highlighting their potential as a clean energy source.

💡Electrochemical cell

An electrochemical cell is a device that transforms chemical energy into electrical energy through redox (reduction-oxidation) reactions. The video emphasizes that fuel cells are a type of electrochemical cell, with the hydrogen-oxygen fuel cell being the most common. The script describes how these cells work by detailing the conversion process from chemical to electrical energy, which is central to understanding the technology's functionality and applications.

💡Hydrogen-oxygen fuel cell

The hydrogen-oxygen fuel cell is a specific type of fuel cell that uses hydrogen as the fuel and oxygen as the oxidizing agent. The video script explains that this cell combines hydrogen and oxygen to form water, while generating electrical energy. This process is environmentally friendly as it does not produce carbon dioxide or other pollutants, making it a promising technology for clean energy solutions.

💡Electrolyte

An electrolyte is a substance that conducts electricity when dissolved in a solvent, typically due to the presence of ions. In the video, the electrolyte, often potassium hydroxide, is described as the medium that allows ions to move between the electrodes in a fuel cell. It plays a crucial role in the cell's operation by facilitating the movement of ions, which is essential for the generation of electricity.

💡Electrodes

Electrodes are the conductive materials through which electric current enters or leaves an electrochemical cell. The video script specifies that in a hydrogen-oxygen fuel cell, there are two electrodes: the anode (negative) and the cathode (positive). These are made of porous carbon and contain a catalyst to speed up the reactions. The electrodes are integral to the cell's function, as they are where the oxidation and reduction reactions occur.

💡Catalyst

A catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change. In the context of the video, catalysts are mentioned as being present in the electrodes of a fuel cell to speed up the reactions between hydrogen and oxygen. This is important for the efficiency of the cell, as it helps to generate electricity more quickly and effectively.

💡Oxidation

Oxidation is a chemical reaction that involves the loss of electrons or an increase in the oxidation state of an atom. In the video, hydrogen undergoes oxidation at the anode, where each hydrogen atom loses an electron to become a hydrogen ion. This process is a key step in the fuel cell's operation, as it sets up the potential difference that drives the flow of electrons and generates electricity.

💡Reduction

Reduction is the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion. The video script describes how, at the cathode, oxygen gains electrons and reacts with hydrogen ions to form water. This reduction process is the complementary reaction to oxidation and is essential for the overall chemical reaction in the fuel cell that produces electricity.

💡Potential difference

Potential difference, also known as voltage, is the measure of the electric potential energy per unit charge in an electric field. The video explains that the oxidation of fuel (hydrogen) in a fuel cell sets up a potential difference across the cell, which drives the flow of electrons through the circuit, thus generating electricity. This concept is fundamental to understanding how fuel cells produce power.

💡Pollutants

Pollutants are substances that contaminate the environment, causing harm to living organisms and ecosystems. The video contrasts fuel cells with traditional energy sources by highlighting that hydrogen-oxygen fuel cells do not produce pollutants like carbon dioxide. This is a significant advantage of fuel cells, as it positions them as a cleaner alternative for energy production.

Highlights

Fuel cells are a type of electrochemical cell that convert chemical energy into electrical energy.

Hydrogen oxygen fuel cells are the most common, combining hydrogen and oxygen to form water and generate electricity.

The electrolyte, such as potassium hydroxide, allows ions to move and is central to the cell's structure.

Electrodes, made of porous carbon with catalysts, are essential for the cell's function.

The anode is negative and the cathode is positive, which is the reverse of electrolysis.

Hydrogen enters the anode compartment and is oxidized, losing an electron to become a hydrogen ion.

Electrons flow through the wire to the cathode, while hydrogen ions move through the electrolyte.

At the cathode, hydrogen ions and electrons react with oxygen to form water.

The reaction requires two sets of hydrogen ions and electrons for every oxygen molecule.

The overall reaction equation shows the combination of oxygen and hydrogen to form water.

The electrical energy comes from the movement of electrons through the wire, which can power any electrical device.

The potential difference across the cell, caused by oxidation, drives the electrons to generate electricity.

Hydrogen oxygen fuel cells offer the benefit of requiring only abundant hydrogen and oxygen, producing no carbon dioxide or pollutants.

Fuel cells are relatively simple, lasting longer and being less polluting to dispose of compared to batteries.

The challenge of hydrogen storage due to its gaseous state and the need for energy to produce hydrogen are mentioned.

The video concludes by discussing the potential of fuel cells to replace fossil fuel engines and batteries in vehicles.

Transcripts

in today's video we're going to take a

look at fuel cells

with a focus on how the hydrogen oxygen

fuel cell works

and also at its pros and cons

now a fuel cell is a type of

electrochemical cell

which means that it converts energy

between electrical

and chemical forms

more precisely though they convert the

chemical energy over fuel and oxygen

into electrical energy that we can then

use to power things

there are a few different types of fuel

cells but the most common is the

hydrogen oxygen fuel cell

which combines hydrogen

and oxygen

to form water

at the same time as generating lots of

electrical energy

the setup of these cells is kind of

complicated

so let's run through the structure first

and then we'll see how it works after

in the very center we have the

electrolyte

which is a solution that ions can move

through

there are lots of different types of

electrolytes but one of the most common

is potassium hydroxide

on either side of this we have the

electrodes

with the negative anode being on the

left

and the positive cathode on the right

and they're connected by a wire on the

top

which allows electrons to flow from the

anode around to the cathode

one of the things that students find

confusing here is that it's the cathode

which is positive

and the anode which is negative

because this is actually the opposite

way around to electrolysis

where it's the cathode which is negative

and the anode which is positive

so just be aware of the difference and

try not to get the two confused

in fuel cells both of the electrodes are

made of porous carbon

which means that they have lots of tiny

holes

and they also contain a catalyst to

speed up the reaction

on the outsides of the electrodes we

have the anode compartment and the

cathode compartment

and each one has an inlet at the top

on the left hydrogen will enter the

added compartment

while on the right oxygen will enter the

cathode compartment

and finally once the reaction is over

all of the water and heat

will then leave by the outlet of the

cathode compartment

now that we know the structure of the

fuel cell we can run through how it

actually works step by step

the first thing to happen is that

hydrogen comes in from the left

and is then oxidized by the anode

which means that each hydrogen atom

loses an electron to become a hydrogen

ion

the equation for this loss of electrons

looks like this

and we'll come back to it in a moment

the electrons though then pass around

the wire to the cathode

while the hydrogen ions move through the

electrolytes to the cathode

this means that the electrons and

hydrogen ions can react with the oxygen

that comes in from the right

and together they all combine to make

water

as you can see though we're left with a

spare oxygen atom

and so we actually need two sets of

hydrogen ions and electrons to react

with each oxygen molecule

and if we put that into an equation then

this will be the reaction that's

happening at the cathode

because each oxygen molecule

reacts with four hydrogen ions and four

electrons

to form two molecules of water

and once that's happened the water then

leaves the fuel cell via the outlet and

the whole process is complete

now these two equations that we have

here are known as half equations

because they show the loss or gain of

electrons

in our case they show the oxidation of

hydrogen

and the reduction of oxygen

and if we combine these two equations

we'd get this overall equation

which shows that we've combined oxygen

and hydrogen to make water

the electrical energy of this reaction

comes from the movement of electrons

through the wire at the top

and although we've shown it as a simple

lamp

it really could be any electrical device

and effectively it would be powered by

the chemical

reaction make things clear if you're

asked how fuel cells work in exams

the key thing to mention

is that as fuel enters the cell

it becomes oxidized

and this sets up a potential difference

across the cell

if we break this down the fuel in this

case is the hydrogen

and by oxidized we just mean that the

hydrogen atoms lose electrons

then the potential difference part just

means that there's a difference in

charge between the two electrodes

and this is what drives the electrons

around the circuit so that we can

generate electricity

the last thing we need to look at are

the pros and cons of these hydrogen

oxygen fuel cells

although we could use fuel cells to

replace things like power stations

the main idea is to use them to replace

the fossil fuel engines and batteries

that we use in vehicles

both of which are polluting

the main benefit is that hydrogen oxygen

fuel cells only require hydrogen and

oxygen

which are both abundant

and they don't produce any carbon

dioxide or other pollutants as waste

another advantage is that fuel cells are

relatively simple devices

which means that they last longer than

batteries do

and they're also less polluting to

dispose of when you want to throw them

away

the downside though is that hydrogen is

a gas

so it takes up way more space to store

than fossil fuels or batteries

it's also explosive when mixed with air

which can make storing it dangerous

the main problem though is that to make

the hydrogen fuel in the first place

requires energy

and that energy often comes from

something like fossil fuels

anyways that's everything for this video

so if you enjoyed it then please do give

us a like and subscribe

and cheers for watching