Which mechanism can cause pressure inside a closed reactor to rise during a chemical reaction?

Which mechanism can cause pressure inside a closed reactor to rise during a chemical reaction?

• A. The process could generate gaseous reaction products
• B. Liquids could be condensed to a liquid at the same temperature
• C. A vent system actively removes gas
• D. The temperature decreases due to cooling

Answer: (C)

In a closed reactor, pressure rises when gas is produced during the reaction. Generating gaseous products increases the number of gas molecules (n) in the fixed reactor volume, so, by PV = nRT, the pressure goes up as long as temperature and volume stay the same. This is the primary way pressure can build in a sealed system. If gas is being vented, or if cooling occurs or condensation happens, those actions tend to lower or prevent pressure rise rather than cause it. A vent removes gas to relieve pressure, while cooling or condensation reduces the amount of gas in the vapor phase, both of which reduce pressure.

In a closed reactor, pressure rises when gas is produced during the reaction. Generating gaseous products increases the number of gas molecules (n) in the fixed reactor volume, so, by PV = nRT, the pressure goes up as long as temperature and volume stay the same. This is the primary way pressure can build in a sealed system.

If gas is being vented, or if cooling occurs or condensation happens, those actions tend to lower or prevent pressure rise rather than cause it. A vent removes gas to relieve pressure, while cooling or condensation reduces the amount of gas in the vapor phase, both of which reduce pressure.