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Which metals are less reactive than hydrogen
Copper, silver, gold, platinum
What happens to hydrogen in a fuel cell
It is oxidised(loses electrons)
What needs to happen for hydrogen to leave the fuel cell
It must react with oxygen to produce water
What happens to oxygen in a fuel cell
It is reduced(gains electrons)
What are the benifits of a fuel cell
Faster to refuel, only produces water, allows reaction to take place at a lower temperature, travel further without refuelling
Ionic equation for neutralisation
OH- + H—> H2O
What is the ionic equation at the cathode(negative electrode)
O2 + 4H+ + 4e- —> 2H2O
What is the ionic equation for the anode( positive electrode)/ first electrode
2H2 —> 4H+ + 4e-
General description of the reaction in a fuel cell
Fuel comes in at the anode and must lose electrons to enter. The electrons travel around the circuit and to leave must be reacted with oxygen, taking on the electrons and leaving as water.
What are the differences between the planetary and nuclear model
Nuclear shows the electrons orbiting in fixed shells. Planetary now accepted
How is oxygen produced at the anode
OH ions gain electrons(oxidised) to produce oxygen and water
What happens to produce oxygen at the anode( electrolysis)
Oh is oxidised
What are the limitations of the particle model
Chemical bonds not represented, represents particles as solid spheres
What is boiling point defined by
The strength of attractive forces between particles
What are the forces in a giant ionic lattice
Strong electrostatic forces of attraction in all directions
What are the melting points of ionic substances
High as lots of energy is needed to overcome electrostatic forces of attraction between particles
Can ionic substances conduct electricity
As a solid no
What is the structure and bonding in diamond
-Each carbon bonded to 4 others -high melting points as lots of energy is needed to break string covalent bonds -does not conduct
Structure and bonding of graphite
• layers of carbon arranged in hexagons • each carbon bonded to three others • one delocalised electron per carbon • layers bonded by weak intermolecular forces • high melting points • soft as layers can slide • can conduct electricity
Structure and bonding of graphene
• a layer of graphite • very strong due to covalent bonds • each carbon bonded to three others • one delocalised electron per carbon • can conduct
What is a large covalent structure called
A giant covalent structure
What is the structure and bonding in polymers
• weak intermolecular forces between molecules • strong covalent bonds within the molecules
How do group 7 elements exist
As diatomic molecules