Question

a. How does pressure affect the solubility of a gas in a liquid? b. What law is a statement of this relationship? c. If the pressure of a gas above a liquid is increased, what happens to the amount of the gas that will dissolve in the liquid, if all other conditions remain constant? d. Two bottles of soda are opened. One is a cold bottle and the other is at room temperature. Which system will show more effervescence and why?

Short answer

Pressure increases gas solubility in a liquid. This relationship is described by Henry's Law. Increased pressure leads to more gas dissolving. A warm soda shows more effervescence because gas is less soluble in warm liquid.

Step-by-step solution

Understanding Pressure and Gas Solubility

Pressure affects the solubility of a gas in a liquid by forcing more gas molecules into the liquid. The higher the pressure, the more gas can dissolve in the liquid because there is more 'push' on the gas molecules to enter the liquid.

Identifying the Relevant Law

The law that describes the relationship between pressure and the solubility of a gas in a liquid is Henry's Law. Henry's Law states that the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid.

Effect of Increased Pressure on Gas Solubility

If the pressure of a gas above a liquid is increased, the amount of gas that will dissolve in the liquid will also increase. This is because the increase in pressure effectively forces more gas molecules into the liquid.

Comparing Effervescence in Soda Bottles

When two bottles of soda are opened, the one at room temperature will show more effervescence compared to the cold bottle. This is because gases are less soluble in warmer liquids, so more gas is released from the liquid, creating more bubbles.

Key concepts

Pressure Effects on Solubility

Pressure has a significant impact on the solubility of gases in liquids. Think of pressure as the force that pushes gas molecules into the liquid. When you increase the pressure above a liquid, you are essentially 'pushing' more gas molecules into the liquid. This means that at higher pressures, more gas can be dissolved in the liquid.
Imagine you have a sealed soda bottle. The carbon dioxide gas is dissolved in the liquid under high pressure. Because of this high pressure, the gas stays dissolved in the liquid until you open the bottle.
Opening the bottle releases the pressure, and the gas escapes in the form of bubbles. This principle is vital in various industries, such as beverage production, where the carbonation level is controlled through pressure adjustments.

Henry's Law

Have you ever wondered why the amount of gas dissolved in a liquid depends on the pressure? This relationship is explained by Henry's Law. Henry's Law states: the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid. In simpler words, if you double the pressure, you double the amount of gas that can dissolve.
The mathematical formula for Henry's Law is given by:
\[ C = kP \]
Where:

• \( C \) is the concentration of the dissolved gas.
• \( k \) is Henry's Law constant, which depends on the specific gas and liquid.
• \( P \) is the pressure of the gas above the liquid.

This law is very useful for understanding how gases behave in different settings. For instance, deep-sea divers have to manage the gas pressures carefully to avoid decompression sickness, also known as 'the bends'.

Temperature Effects on Gas Solubility

Temperature plays a crucial role in the solubility of gases in liquids. Generally, gases are less soluble in warmer liquids. This means that as the temperature increases, the amount of gas that can be dissolved in a liquid decreases.
Why does this happen? In a warmer liquid, gas molecules gain more kinetic energy, making it easier for them to escape from the liquid's surface. Picture heating a pot of water; as the water gets hotter, more vapor (gas) leaves the surface.
This principle is why sodas are usually kept cold. Cold temperatures keep more carbon dioxide dissolved, making the soda fizzy for longer.

Effervescence in Soda

Effervescence refers to the bubbles that form when a gas escapes from a liquid. You've probably noticed that when you open a bottled soda, bubbles form rapidly. This bubbling, or effervescence, is more noticeable at room temperature than when the soda is cold.
Let's break down why. At room temperature, the solubility of carbon dioxide in the soda decreases, causing more gas to escape and form bubbles. On the other hand, a cold bottle of soda retains more of its dissolved gas, resulting in fewer bubbles when opened.
In essence, if you want your soda to be less fizzy, keep it cold. If you prefer more bubbles, a room temperature bottle will provide that extra effervescence.