Last week, Slate published the first installment of the "Green Challenge," a program that helps participants reduce the amount of carbon dioxide they put into the atmosphere. We started by asking people to think about the effects their cars have on the environment: "For each gallon of gas your car burns, it releases about 19 pounds of carbon dioxide." Explainer readers wondered about this statistic: If a gallon of gasoline weighs about 6 pounds, how can it produce three times that much greenhouse gas?
The carbon from the gasoline mixes with oxygen from the air. Gasoline consists mostly of hydrocarbons-chains of carbon encircled by atoms of hydrogen. When the hydrocarbons burn, they break apart and recombine with the air. This reaction produces heat, as well as two chemical byproducts: water and carbon dioxide.
For example, consider a single molecule of octane-a typical hydrocarbon that you'd find in gasoline. Octane consists of eight atoms of carbon and 18 atoms of hydrogen, written as C8H18. If you break down the octane and mix it with enough oxygen (O2), you've got the ingredients-i.e., the atoms of carbon, hydrogen, and oxygen-to make eight molecules of carbon dioxide (CO2) and nine molecules of water (H2O). The eight molecules of CO2 weigh about three times more than the one molecule of octane you started with. That doesn't mean you've violated the law of conservation of mass; instead, you've added the weight of the oxygen from the air to the weight of the carbon from the gasoline. (For a more in-depth discussion of this reaction,
This reaction gives only a general sense of what happens when you burn a gallon of gas. First, the combustion that occurs in a car engine doesn't work perfectly, which means not every hydrocarbon gets converted into carbon dioxide and water vapor. Sometimes there's not enough oxygen available to complete the reaction, in which case hydrocarbons can be converted into poisonous carbon monoxide (CO). Burning gasoline can also release nitrous oxide and other gases.
Second, gasoline consists of octane along with many other kinds of hydrocarbons. You'll also find additives like surfactants, freezing-point depressants, corrosion inhibitors, and dyes. These nonhydrocarbon additives might make up half a percent of the total composition of the gasoline. There are also differences between winter and summer blends, low- and high-octane, and leaded and unleaded.
Thus, any estimate of the amount of carbon dioxide that comes from a gallon of gas must be based on some assumptions. The Environmental Protection Agency starts with a guess for how many grams of carbon are in each gallon of gas. First, they determine how much carbon is in each particular kind of gasoline, and then they come up with a weighted average based on consumption levels for each variety. Using this method, they estimate that a gallon of gas contains, on average, 2,421 grams of carbon. That's enough to make 8,877 grams of CO2. They multiply that number by 0.99 to account for the carbon that doesn't react fully with the oxygen. Their result: 8,788 grams, or about 19.4 pounds. (The Energy Information Administration gives a slightly higher number-19.564
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The density of gasoline octane can vary depending on the specific formulation, but on average, it is around 720 to 750 grams per liter at a temperature of 15 degrees Celsius.
Density of Octane= .703g/ml=703G/Litre
3.78541 Litres/Us Gal
So gram/gallon= 703G/Litre x3.78541 Litres/Us Gal=2661.14323 gram/gallon of Octane
13 grams per liter is equivalent to 1.3 grams per deciliter. This conversion is because there are 10 deciliters in 1 liter.
To convert parts per million (ppm) to grams per liter, you first need to convert ppm to milligrams per liter (since 1 ppm is equivalent to 1 mg/L) and then to grams per liter: 10 ppm = 10 mg/L Now, convert milligrams to grams: 10 mg = 0.01 grams Therefore, a liter of water with 10 ppm phosphorus would contain 0.01 grams of phosphorus.
The molar mass of ammonia (NH3) is 17 g/mol. Therefore, one mole of ammonia weighs 17 grams. Since one liter of gas at STP (standard temperature and pressure) contains 22.4 liters per mole, this means that a liter of ammonia gas would weigh 17 grams.
Approximately 770 grams of ammonium sulfate can dissolve in one liter of water to form a saturated solution at room temperature.
Gasoline is a fuel blend that typically contains a mixture of hydrocarbons, including benzene. Benzene is a specific chemical compound that is a component of gasoline. Benzene is a known carcinogen and is regulated for its environmental and health risks, whereas gasoline is a general term for a fuel used in internal combustion engines.