Question

To collect a beaker of \(\mathrm{H}_{2}\) gas by displacing the air already in the beaker, would you hold the beaker upright or inverted? Why? How would you hold the beaker to collect \(\mathrm{CO}_{2}\) ?

Short answer

Hold the beaker inverted for \(\text{H}_2\) and upright for \(\text{CO}_2\).

Step-by-step solution

Understand the Properties of \(\text{H}_2\) Gas

\(\text{H}_2\) gas is less dense than air, so it will rise above the air when released. Therefore, to collect \(\text{H}_2\) gas, the beaker should be held inverted to allow the gas to displace the air and fill the beaker from the bottom.

Understand the Properties of \(\text{CO}_2\) Gas

\(\text{CO}_2\) gas is denser than air, so it will sink below the air when released. Therefore, to collect \(\text{CO}_2\) gas, the beaker should be held upright to allow the gas to displace the air and fill the beaker from the bottom.

Determine the Correct Orientation for Each Gas

For collecting \(\text{H}_2\) gas, hold the beaker inverted. For collecting \(\text{CO}_2\) gas, hold the beaker upright.

Key concepts

hydrogen gas properties

Hydrogen is the lightest gas known, and it has some unique properties. It is colorless, odorless, and tasteless. Hydrogen is less dense than air, making it much lighter. Because of its low density, hydrogen gas will rise in the atmosphere when released.
When collecting hydrogen gas, its lightness plays a crucial role. If you want to gather this gas for any experiment or observation, you need to hold the collection container (like a beaker) upside down. This way, the hydrogen, being lighter, can fill up the beaker from the bottom as it displaces the air inside.

carbon dioxide gas properties

Carbon dioxide is different from hydrogen in both weight and behavior. It's also colorless and odorless but denser than air. Because it is heavier, carbon dioxide tends to sink below air when released.
When you need to catch carbon dioxide gas, consider its density. To collect it efficiently, you should hold an upright beaker. This orientation allows the heavier CO₂ to move down, displacing the air and gradually filling the beaker from the bottom up. This method ensures that the gas does not escape and you have a successful collection.

gas density

Gas density is crucial for understanding different collection methods. Simply put, density is the mass of gas per unit volume. Gases with lower density than air, like hydrogen, rise because they are lighter. Gases heavier than air, like carbon dioxide, sink.
Here's a handy way to remember how to collect different gases:

• For light gases like hydrogen, use an inverted container. The gas will rise and fill the space from the bottom.
• For heavy gases like carbon dioxide, use an upright container. The gas will move down and displace the air from the bottom.

Understanding density helps you effectively capture gases and use them in your experiments or studies.