Prior Knowledge: What C is a solid fuel? What H is used in rockets? M H K P W FC What C is a solid fuel? What H is used in rockets? What M is found in natural gas? What W produces a lot of ash when it burns? What P and K are obtained from crude oil? What FC uses hydrogen to make electricity? Stretch: Can you suggest one advantage and one disadvantage of using hydrogen as a fuel for a car.

Fuel Cells Objectives: Describe how a fuel cell works Evaluate the use of hydrogen fuel cells HT: Write half equations for the electrode reactions in the hydrogen fuel cell Keywords: Fuel Cell

Watch https://www.youtube.com/watch?v=oy8dzOB-Ykg

Fuel cells: Using hydrogen as a fuel could help to reduce the human impact on global warming because the reaction does not produce carbon dioxide. hydrogen + water  water However, there are still some problems of safety and storage that need to be solved. Supplying the hydrogen to burn in car engines is also an issue. Making hydrogen using electrolysis requires electricity. A more efficient use of the energy from oxidising hydrogen is in a fuel cell. These cells are fed with hydrogen and oxygen and they produce water. Most of the energy released is transferred into electrical energy and this can be used to run a vehicle. However, a constant supply of hydrogen is still needed to run the fuel cell.

Working of a fuel cell: Suggest some advantages and disadvantages to using a hydrogen fuel cell Find a diagram of the working of a hydrogen fuel cell and describe along side it how it works. Write two half equations that show what happens to the hydrogen and oxygen gases in a hydrogen fuel cell. Stretch: Explain how the government could get more people to buy cars powered by fuel cells. Give your opinion on the use of cars with fuel cells as opposed to ‘normal’ engines.

Peer Assess: Suggest some advantages and disadvantages to using a hydrogen fuel cell Advantages: Do not need to be electrically recharged No pollutants are produced Can be a range of sizes for different uses Disadvantages: Hydrogen is highly flammable Hydrogen is sometimes produced from non-renewable resources Hydrogen is difficult to store Hydrogen supplied to the negative electrode. It diffuses through the graphite electrode and reacts with hydroxide ions to form water and provides a source of electrons to an external circuit. Oxygen gas is supplied to the positive electrode. It diffuses through the graphite and reacts to form hydroxide ions, accepting electrons from the external circuit. Write two half equations that show what happens to the hydrogen and oxygen gases in a hydrogen fuel cell. 2H2(g) + 4OH-(aq)  4H2O(l) + 4e- O2 + 2H2O(l) + 4e-  4OH-(aq) Stretch: Answers to the stretch task will be personal opinions.

Experiment Make your own fuel cell Your teacher will show you how Find what it can power?

To make the fuel cell, we need the following: One foot of platinum coated nickel wire, or pure platinum wire. ... A popsickle stick or similar small piece of wood or plastic. A 9 volt battery clip. A 9 volt battery. Some transparent sticky tape. A glass of water. A volt meter.

Hydrogen combustion is exothermic https://www.youtube.com/watch?v=Tk_iIzOUjTU H2 + O2  H2O Place the following in to a table of advantages and disadvantages of fuel cells Gases take up a lot of space so must be pressurised No CO2 released Hydrogen fuel cells are very efficient Getting H2 takes energy which could be obtained by burning fossil fuels

Evaluate the use of hydrogen to power cars (6 MARKS) Points to include Hydrogen can be burned as a fuel in combustion engines. hydrogen + oxygen  water 1. It can be a renewable source of electricity if the hydrogen comes from a renewable resource. 2. It does not produce pollution or contribute to global warming because the only product is water. What are the Disadvantages of a Hydrogen Fuel Cell? 1. Each fuel cell only makes a small voltage. A large number of fuel cells must be wired together to produce a large voltage or current. This is expensive. 2. Hydrogen is explosive and difficult to store. 3. If the hydrogen does not come from a renewable resource but is made from methane, then the electricity produced from the fuel cell is also not renewable.  

Peer assessment Used the equation for the reaction. Hydrogen can be burned as a fuel in combustion engines. hydrogen + oxygen  water Given one advantage of a fuel cell Given one disadvantage Given 2 advantages Given 2 disadvantages Give an opinion if fuel cells are an alternative to fossil fuels with justification.

Reflect: Select two numbers between 1-25, write these in the margin of your book. Now complete the sentence/question from the numbers that you have chosen…