2015 AP Chemistry free response 2a (part 1 of 2) | Chemistry | Khan Academy

TL;DR

The content explains the process of dehydrating ethanol to produce ethene and provides calculations to determine the number of moles of ethene produced.

Transcript

• [Voiceover] Ethene, C2H4, molar mass of 28.1 grams per mole, may be prepared by the dehydration of ethanol, C2H5OH, molar mass 46.1 grams per mole, using a solid catalyst. A setup for the lab synthesis is shown in the diagram above. The equation for the dehydration reaction is given below. So, we have the ethanol, and then in the presence of a ca... Read More

Key Insights

• ❓ Ethene can be produced by dehydrating ethanol using a solid catalyst.
• 🫢 The volume of gas collected during the experiment can be used to calculate the number of moles of ethene produced.
• 💦 The partial pressure of ethene can be determined by subtracting the vapor pressure of water from the total pressure.

Questions & Answers

Q: How is ethene produced from the dehydration of ethanol?

Ethene is produced from the dehydration of ethanol through a chemical reaction in the presence of a solid catalyst. The reaction yields ethene and water.

Q: What is the purpose of the experiment described in the content?

The purpose of the experiment is to determine the number of moles of ethene produced during the dehydration of ethanol. This allows for the calculation of the percent yield of ethene.

Q: How is the partial pressure of ethene calculated?

The partial pressure of ethene can be calculated by subtracting the partial pressure of water from the total pressure. The partial pressure of water is determined by converting the vapor pressure of water from torr to atmospheres.

Q: How is the number of moles of ethene calculated in the experiment?

The number of moles of ethene can be calculated using the Ideal Gas Law equation. By knowing the partial pressure of ethene, volume, gas constant, and temperature, the number of moles can be determined.

Summary & Key Takeaways

• Ethanol can be dehydrated using a solid catalyst to produce ethene and water.

• A student conducted an experiment where they added a sample of ethanol to a test tube and heated it until all the ethanol evaporated and gas generation stopped.

• The volume of gas collected was measured, along with the total pressure and temperature, to calculate the number of moles of ethene produced.