Question

When a reaction is attached to a hydrogen balloon under slightly higher pressure than atmospheric pressure, what would be the jest way to take a sample for tlc?

a. Just pull off the stopper and quickly take a sample and return the stopped as fast as possible.
b. Remove the hydrogen balloon, then pull off the stopper, quickly take a sample, return the stopper as fast as possible, and then replace the H₂ balloon.
c. Remove the hydrogen balloon being careful to close off the bottom of the balloon to keep the hydrogen from escaping, then pull off the stopper, quickly take a sample, retum the stopper as fast as is safe, and then replace the H₂ balloon.
d. Remove the hydrogen balloon being careful to close off the bottom of the balloon to keep the hydrogen from escaping, then pull off the stopper, quickly take a sample, retum the stopper as fast as is safe, and then replace the H₂ balloon. Finally, insert another needle through the stopper and repurge the headspace of air so that it only has hydrogen.
e. It is not possible to monitor hydrogenation reactions by tlc.

Answer 1

To take a TLC sample in a pressurized hydrogen environment, quickly seal off the balloon and replace the stopper. Techniques like gas collection by water displacement can also be used to prevent the gas from escaping.

Step-by-step explanation:

To take a sample for Thin Layer Chromatography (TLC) from a reaction that is being conducted under slight pressure by a hydrogen balloon, you would need to be especially careful not to let the hydrogen escape through the hole created when opening the reaction vessel. One method to sample in such cases involves briefly removing the hydrogen balloon, ensuring that the bottom of the balloon is sealed quickly to prevent hydrogen release, then swiftly replacing the stopper and reattaching the balloon.

Alternatively, techniques like gas collection by water displacement can be utilized, where gases are collected in an inverted bottle filled with water within a larger pan of water, preventing gas escape. Another approach involves the removal of the reaction flask from heat to let the gaseous sample condense back to liquid for weighing, thus determining the mass of the sample. It is important to consider the properties and safety measures when dealing with hydrogen as it's a highly flammable gas and can pose risks if not handled correctly.