Standard Temperature and Pressure Video Lessons

Concept: Understanding Standard State Conditions

# Problem: An herbicide is found to contain only C, H, N, and Cl. The complete combustion of a 100.0-mg sample of the herbicide in excess oxygen produces 83.16 mL of CO2 and 73.30 mL of H2O vapor at STP. A separate analysis shows that the sample also contains 16.44 mg of Cl.Determine the percent composition of the substance.

###### FREE Expert Solution

The gases are at STP (standard temperature and pressure) where T = 0oC (273.15 K) and P = 1 atm. At STP, 1 mole of any ideal gas occupies 22.4 L of volume.

Knowing this information, the number of moles of each gas can be calculated:

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###### Problem Details

An herbicide is found to contain only C, H, N, and Cl. The complete combustion of a 100.0-mg sample of the herbicide in excess oxygen produces 83.16 mL of CO2 and 73.30 mL of H2O vapor at STP. A separate analysis shows that the sample also contains 16.44 mg of Cl.

Determine the percent composition of the substance.