Chemical Equation Checklist
With the application of hydraulic fracturing techniques, the
availability of natural gas has skyrocketed, while the cost plummeted.
Some coal-fired power plants are retrofitting for natural gas. Most new
plants in planning and construction within the U.S. are designed for
natural gas. Large fleet vehicles like buses and garbage collection
trucks are being manufactured to run on natural gas. There are many
angles that you can evaluate the environmental impacts of a fuel,
including the environmental footprint of procurement, processing
requirements, and spill or accidental release hazards.
While natural gas reserves can be accessed through fracking,
landfills are another source of natural gas. Decomposition at landfills
generates natural gas. At a closed 20 hectare landfill with active gas
recovery, methane emissions collected through vertical and horizontal
piping equals 1,820kg CH4 per day. While this sounds big, in
the U.S. alone, landfills contribute over 100 million metric tons of
methane to Earth’s atmosphere each year. That is a big number. This is
especially important because methane is a much more potent greenhouse
gas than carbon dioxide!
Increasingly, landfills install gas-to-energy collection systems, which generally demonstrate high combustion efficiency.
Combustion efficiency is a measure of how well the heat energy released
through fuel combustion is being used in the combustion process.
Combustion efficiency is influenced by the identity of the fuel,
temperature, and amount of oxygen present. When fuel and oxygen are in
perfect balance, the combustion is stoichiometric and complete combustion occurs. In reality, the perfect mixing of air and fuel does not occur, resulting in incomplete combustion (and thus lowering combustion efficiency).
Consider: Choose one (1) of the following to respond to with your initial post.
When you balance a chemical equation, there are steps you should
follow. Develop a checklist to apply the balancing of the combustion
equation for methane complete combustion (forming carbon dioxide and
water) and incomplete combustion (forming carbon monoxide and water).
The checklist should be a bulleted list of action items that starts with
guiding you through writing the proper chemical formulas (including
subscripts) and ends with establishing proper coefficients.
When you balance a chemical equation, you can perform stoichiometric
calculations to predict the yield of one or more products.
Acknowledging that 100% combustion efficiency is not possible, discuss
the pollution resulting from the combustion of landfill methane.
Specifically, your answer should demonstrate a strong knowledge of
stoichiometry and combustion reactions.
Some ideas for reply posts:
Identify the best aspects from checklists of your peers; discuss how
you will incorporate their contributions into your checklist.
Identify flaws in the checklists of your peers (gently, please) and suggest edits. Your checklist should:
Be bulleted, short action items.
Start with writing the proper chemical formulas based on the
chemical name and end with a properly balanced equation (proper
coefficients and subscripts).
Discuss how you used your checklist in your homework/quiz. (Did it
help? Did you still get the question wrong? Did using the checklist
prompt you to edit your checklist to make it even better for future
use?)
More deeply explore the chemistry of methane combustion, connecting
to ideas we learned in this module and what we’ve learned in previous
modules.