Chemistry Case Study: Analyzing the Corals in Crisis Phenomenon

This chemistry case study, titled "Corals in Crisis," examines the impact of increasing atmospheric CO2 levels on coral reefs and the broader marine environment. The study begins by balancing chemical equations and calculating the mass of CO2 produced from gasoline combustion, then extends to determining the amount of CO2 the US and the world would produce. It then analyzes the effects of CO2 on seawater chemistry, including calculations using Henry's Law, solubility equilibrium, and Le Chatelier's principle to predict how increased CO2 affects calcium carbonate formation. The study also explores the relationship between atmospheric CO2, seawater CO2, and ocean pH, using graphs and data analysis to predict future CO2 levels and their impact on ocean pH. The study also addresses the analogy of coral as the "canary in a coalmine," discussing coral bleaching, its causes, and potential solutions, emphasizing the role of human activities and climate change in the crisis. The study highlights the importance of reducing carbon footprints and promoting sustainable practices to protect coral reefs and marine ecosystems.

Running head: CORAL IN CRISIS 1
Corals in Crisis: A Chemistry Case Study
Name
Institution

CORAL IN CRISIS 2
Corals in Crisis: A Chemistry Case Study
1. Start by balancing the chemical equation above.
2C8H18 (l) + 25O2 (g) 16CO2 (g) +18 H2O (g)
2. The density of gasoline is 0.7489 g/mL. Since one gallon of gasoline is equal to 3785 mL,
calculate the mass of one gallon of gasoline.
Mass=density * volume
=0.7489 g/mL *3785 mL
=2834.5865g
=2.835kg
3. Determine the mass of CO2 produced from the combustion of one gallon of gasoline
(octane).
2C8H18 (l) + 25O2 (g) 16CO2 (g) +18 H2O (g)
As shown above, for every two octane molecules that goes to the combustion reaction, 16 CO2
molecules are emitted. Two determine the number of grams of carbon dioxide produced; we will
first calculate the molecular mass of CO2, the molecular mass of octane and the ratio involving
the two
(1m*12.01 amu) + (2 m*15.99 amu)

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=44.009 amu……………………………………………………………….molecular mass of CO2
(8m * 12.01 amu) + (18 m * 1.008 amu)
= 114 233 amu…………………………………………………….. molecular mass of octane
We therefore calculate the ratio between the two,
44.008 amu/ 114,233 amu
= o.385
For every octane molecule that enters the reaction, it produces 8 carbon dioxide molecules, one
carbon dioxide molecule is 38.5% the total mass of octane molecule, and therefore, we can
calculate the number of grams of CO2 by one gram of octane/gasoline
8* 0.385
= 3.08 g CO2/g C8H18
Because the density of octane is 2,661.144 g/gal or 0.703 g/ml, therefore, we can calculate the
amount of CO2 produced by one gallon of gasoline
2 661.14g / gallon * 3.08 g * 1 lb /453.59 g
=18.07 lbs CO2 /gal
18.07 pounds

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4. On average, the US currently consumes 840 gallons of oil per day for each person. If all
of this oil were burned as gasoline, how much CO2 would the US produce per person every
day?
840 gallons *18.07 lbs
=15178.8 lbs
5. The population of the US as of 2019 is approximately 327 million people. Based on your
previous answer, how much total CO2 would the US produce each day?
327 million *15178.8 lbs
=4963467600000 lbs
=(4.9635 *1012 ) lbs
6. How much total CO2 would the US produce in a year?
4963467600000 lbs * 365 days
= 181166567400000 lbs
= (1.8117 * 1014 ) lbs
7. The world population is estimated at 7.7 billion as of 12 December 2019. If everyone in
the world used as much oil as each US citizen, how much CO2 would be produced each
year?
(1.8117 * 1014) lbs *7.7 * 10 9
= (1.3950 * 1024 ) lbs

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One Effect of CO2
1. Use the data in Table 1 to calculate and compare the concentrations (Molarity) of CO2 in
water in 1820 and 2020. Use k = 3.4 x 10-8 M/ppm.
Sg= k Pg
Where
Sg- solubility of the gas
K- Henry’s law constant for the gas
Pg- Partial pressure of the gas.
In the above question, we will use Henry's Law to calculate the concentration of dissolved in
water.
[CO2] = Pg/KH
= 282.35 ppm / 3.4 x 10-8 M/ppm.
=8.3044 * 109 M………………………………………………………..1820
[CO2] = Pg/KH

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=410.00 PPM / 3.4 x 10-8 M/ppm.
= 1.2059 * 1010 M……………………………………………………..2020
As it can be clearly seen, the concentration of carbon dioxide in 2020 is more as compared
to1820
2. Calcium Carbonate is secreted by coral polyps and forms the stable structure that allows the
coral to thrive. Calcium carbonate is only slightly soluble in water, and can be represented by an
equilibrium chemical equation, with a solubility equilibrium constant Ksp= 3.36 x 10-9.
a) Write the chemical equation for the dissolution of solid Calcium carbonate.
CaCO3 (s) + CO2 (g) + H2O(l) → Ca (HCO3)2 (aq)
b) Write the expression for the equilibrium constant, Ksp, for this process.
CaCO3(s) ⇌ Ca2 + (aq) + CO2−3(aq) Ksp =[Ca2+][CO3−2]
c) Apply Le Chatlier’s principle to predict how an increase in atmospheric CO2 might affect the
available calcium ions in the ocean and the result on species, such as coral, that use the calcium
ions to build structures. This multi-step equilibrium is represented in the following equation:
CO2 (aq) + 3H2O (l) ↔ H2CO3 (aq) + 2 H2O ↔ H3O+ (aq) + HCO3- (aq) + H2O ↔ CO32-
(aq) + 2 H3O+ (aq)

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solution
Le Chatlier’s principal states that, a perturbation for instance by increasing CO2 will lead to an
equilibrium shift in a way that will minimize the perturbation and as such, it will move the
direction that balances the equilibrium. The concentration of carbon dioxide will go up but on the
other hand, the concentration of CO32- will go down. Further, the concentration of HCO3– will
slightly go up but on the and there will be more HCO3– and the final change in HCO3– will be
smaller as compared to CO2 and CO32-. At the end, CO2 and CO32- are almost inversely related to
each other.
8. What conclusions can be drawn from the data in Figure 2? Summarize the graph in a
brief statement.
Solution
The global atmospheric carbon dioxide concentration in parts per millions for the last 300 years
has been on increase. However, during the ice –ages (pre-1958), carbon dioxide concentration
was never higher than 300 ppm. The warmer interglacial era that is post-1958 the concentration
has been rapidly increasing to the current records of more than 400ppm. From the graph, it is
clear from the black line in the graph that is post-1958, the concentration looks virtually
instantaneous.
CO2 concentration rising may be attributed to the rising use of fossil fuels that people are using
as a form of energy. When the fossil fuels such as coal and oil (contain carbon) are pulled out to

CORAL IN CRISIS 8
the atmosphere through photosynthesis, the increase in carbon dioxide concentration in the
atmosphere increases.
9. Skeptics who do not believe that humans are having an impact on our environment often
argue that the levels of CO2 have fluctuated in the past as the earth has gone through its
natural cycles. Use the data presented in the graph above to address this argument.

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Solution
From the graph shown below, it is very clear that from the age Neanderthal man was discovered
to the end of ice age, the average global carbon dioxide concentration in the atmosphere
fluctuated between 165ppm to 280ppm. However, when human started to bun fossil fuels from
the first industrial revolution to the bitcoin era, the trend has changed rapidly. The number has
risen to more than 300 ppm, and worst of all, it has crept above 400 ppm in the recent years.
From the below graph and other underlying factors, it is evident that humans and human
activities have the greatest impact on the environment. Industrialization has caused the levels of
CO2 concentration to skyrocket and we cannot blame this to natural cycles in the universe. The
graph has gone abnormally high after the increase of human activities. However, from the first
signs of Neanderthal to the begging of ice-age period, we can partially relate the changes to
natural cycles because there are less human activities and the graph is regular and predictable.

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10. What are the relationships between atmospheric CO2, seawater CO2 and pH of the
oceans?
Solution
As shown in the graph it is evident that an increase in amount of CO2 concentration in the
atmosphere causes an increase in carbon dioxide dissolving into ocean water. The relationship
between atmospheric CO2, seawater CO2 and pH of the oceans is interrelated, dissolved carbon
dioxide in sea water increases the hydrogen ion (H+ ), in sea water and therefore decreases the PH
of the ocean as shown in the equation below. The acidity level has been increasing because of the
increase I human activities leading to increase in carbon dioxide in the air and the ocean
CO2 (aq) + H2O ⇌ H2CO3 ⇌ HCO3− + H+ ⇌ CO32− + 2 H+.

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11. From the graph of [CO2] versus time from 1955 to 2015, determine the slope of the best
fit straight line. Use this slope to predict the [CO2] in the year 2100 at the current rate of
increase.

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From the above graph, we will calculate the gradient of the graph from the above extrapolated
lines of best fit. In this case we will take change in y axis over change in X axis.
= change∈Δ y
change∈ Δ x
= 400−375
2015−2005
= 25
10
=1.5ppm/ year