Solar Energy (HL Option C.4) Flashcards
What do chloroplasts absorb? How?
They absorb sunlight by using chlorophyll
What is a conjugated system?
extended system of alternating single and double bonds
What is the net ionic equation of photosynthesis?
6 carbon dioxide + 6 water -> Glucose + 6 oxygen
How does photosynthesis work?
absorbing photons of light (visible spectrum) excites electrons, electrons move back to the ground state through a complex set of reactions which results in the production of glucose and oxygen
Why are pigments in plants coloured?
conjugated double bond systems
What pigment specifically, causes plants to be coloured?
anthocyanin
What is a resonance structure?
When there is more than one possible position for a double bond in a molecule.
What is biofuel?
substance whose energy is derived from carbon fixation in plants
How are biofuels obtained?
fermentation of glucose
What does it mean to be carbon neutral?
no net release of carbon dioxide into the environment
Why is biofuel added to petrol?
The carbon dioxide produced in combustion, equals the carbon dioxide which is used in photosynthesis, so the fuel is carbon neutral
What is biodiesel?
sustainable diesel which is drawn from vegetable oil
What is the benefit of making biodiesel from vegetable oil?
vegetable oil releases a similar amount of energy when it is burnt
What can’t straight vegetable oil be used as biodiesel?
It is too viscous, which means there are strong intermolecular forces, therefore it does not vaporize easily and will undergo incomplete combustion
What is transesterification?
vegetable oils are turned into less viscous esters
What are the advantages of using biodiesel?
higher flash point, lower carbon footprint, more easily biodegradable, sustainable, good solvent (for cleaning)
What are the disadvantages of using biodiesel?
more viscous than diesel (even when converted), lower energy content than regular diesel, increases food prices, more costly than making diesel from fossil fuels, contains more nitrogen (releases more NOx), dirt cleaned from engines causes car to stall
