Dalton's Law of Partial Pressures tells us that when we have a mix of gases that don’t react with each other, the total pressure is the sum of the pressures of each gas.

We can write it like this:

$$P_{\text{total}} = P_1 + P_2 + P_3 + \ldots + P_n$$

Here, $P_{\text{total}}$ is the total pressure, and $P_1, P_2, ..., P_n$ are the pressures of each gas in the mixture.

Everyday Uses of Dalton's Law

1. Gases in the Air:

   • The air around us is mostly made of nitrogen (78%) and oxygen (21%), along with a tiny amount of carbon dioxide (0.04%) and other gases.
   • At sea level, the total air pressure is about 101.3 kPa.
   • We can figure out the pressures of the main gases like this:
     • Nitrogen: $P_{\text{N}_2} = 0.78 \times 101.3 \text{ kPa} \approx 79.03 \text{ kPa}$
     • Oxygen: $P_{\text{O}_2} = 0.21 \times 101.3 \text{ kPa} \approx 21.23 \text{ kPa}$

2. How We Breathe:

   • When we breathe in, the gases in our lungs change.
   • Dalton's Law helps us understand how oxygen moves into our blood. It shows how the pressure of oxygen in tiny air sacs in our lungs pushes it into our bloodstream.

3. Use in Industry:

   • In jobs like welding, different gases like argon and carbon dioxide are blended.
   • Dalton's Law helps workers calculate the right pressures for these gases. This is important because it influences the stability of the welding arc and how good the weld is.

Learning about Dalton's Law helps us understand how gases act in many natural situations and in industries. This knowledge is important in areas like environmental science, how our lungs work, and chemical engineering.