To figure out how the volume of gas changes during chemical reactions, we use two main ideas: stoichiometry and the Ideal Gas Law.

1. What is the Ideal Gas Law?

The Ideal Gas Law is a formula that helps us understand how gases behave. It looks like this:

$PV = nRT$

Let’s break that down:

• P = Pressure (measured in atmospheres, or atm)
• V = Volume (measured in liters, or L)
• n = Number of moles (this tells us how many gas particles we have)
• R = Ideal gas constant (0.0821 L·atm/(K·mol))
• T = Temperature (measured in Kelvin, or K)

2. Understanding Stoichiometric Relationships

Stoichiometry helps us see the relationships between the amounts of different substances in a reaction.

We use balanced chemical equations to find out the ratio of moles.

For example, in this reaction:

$aA + bB \rightarrow cC + dD$

The ratio $\frac{c}{a}$ tells us how many moles of gas C are produced compared to how many moles of gas A are used up.

3. How to Calculate Volume

We can calculate the volume of gas by rearranging the Ideal Gas Law like this:

$V = \frac{nRT}{P}$

To find out how many moles (n) we have, we use stoichiometry based on our reaction ratios before calculating how the volume changes.

By using these ideas together, we can accurately predict how the volume of gas will change during reactions.