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Law of Definite Proportions

Problem: CO2 is released from burning gasoline from automobiles. The atomic mass of carbon is 12 amu and the atomic mass of oxygen is 16 amu per one mole. The total atomic mass of CO2 is 44amu. If 2 pounds of CO2 is released by one taxi during the course of one day, how many grams of carbon and oxygen would there be?

Answer: First you have to convert two pounds into grams using the factor label method.

2 pounds x 454 grams/ 1 pound=908 grams. 908/ 11 parts= 82.5 grams.

Carbon: 82.5 grams x 3 = 248 grams of carbon

Oxygen: 82.5 grams x 8 = 660 grams of oxygen

Law of Multiple Proportions

Problem: Carbon can react with oxygen in two different proportions, creating carbon monoxide or carbon dioxide. If a fixed mass of 100 grams of carbon reacts with 75 grams of oxygen to produce CO and 150 grams of oxygen to produce CO2, what is the ratio of masses of oxygen that can react with 100 grams of carbon?

Answer: 75 grams: 150 grams = 1:2, which is a small, whole number ratio.

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