lab 5 - fermentation Flashcards
what are some concerns about using corn ethanol as fuel
low amount of fuel produced per hectare of crop
increased eutrophication and groundwater pollution
production still contributes to greenhouse gases
what is the primary biofuel crop in NA
corn
what are the advantages of sugarcane over corn
more ethanol produced per land
refineries derive most of their energy from burning sugarcane residue
what is the problem with sugarcane as a biofuel
rainforests cleared to make room for sugarcane
CO2 released into atmosphere from the cutting and burning of trees
CO2 released form decaying tree roots and organic matter
what are the disadvantages of sugarcane and corn based biofuel production
drive food prices up
decrease global food security
corn = leading source of animal feed (higher corn prices = higher food prices)
how is bioethanol produced
when carbs are fermented by yeast
what is yeast
general term for a type of fungus that grows as a single cell and reproduces by budding
which yeast was used in this experiment
saccaromyces cerevisiae
used by humans to produce ethanol through fermentation
also used to make bread (different strain than alcohol formation)
what is the chemical equation for the fermentation process
glucose + water –> ethanol (C2H5OH) + 2CO2 + water
can carbs other than glucose be used in the fermentation process
yes
need to be broken down into simple sugars
between sugarcane, corn, and barley, which contain the greater proportion of simple carbs, complex carbs (starch), and structural carbs (cellulose)
simple carbs = sugarcane
complex carbs = corn
structural carbs = barley
why don’t alcoholic beverages reach concentration >18% without supplementation
ethanol produced becomes toxic to the yeast cells once the alcohol concentration reaches a certain level
why can CO2 production be used as a measure of fermentation / ethanol production
equal ratio of each produced - one molecule of CO2 produced = one molecule of ethanol produced
how to calculate w/v% (weight/volume percentage concentration) and what are the units
units = g/100mL
(how many parts of the solute are present in 100 parts of solvent)
= (mass of solute)/(volume of solvent) * 100%
ex: 5% (w/v) yeast solution has 5g of yeast in 100mL of water
what is biofuel
fuel made from plant biomass produced by photosynthesis
