When we think about stoichiometric calculations in gas reactions, some classic examples can really help us understand the ideas better. Here are a few important ones:

1. Combustion Reactions: One of the most common examples is burning hydrocarbons. Take propane ($C_3H_8$) for example. When it burns, it reacts with oxygen and can be shown like this:

   $C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O$

   This equation tells us that if you know how much propane you have, you can easily figure out how much oxygen is needed. You can also find out how much carbon dioxide and water is produced. This works because gases act in a predictable way when they are at the same temperature and pressure.

2. Avogadro's Law in Reaction Stoichiometry: Avogadro's law is a helpful rule that says if gases are at the same temperature and pressure, they have the same number of molecules in equal volumes. This is really useful! For example, if you have 2 liters of hydrogen gas ($H_2$) reacting with 1 liter of oxygen gas ($O_2$) to make water ($H_2O$):

   $2H_2 + O_2 \rightarrow 2H_2O$

   From this, you can see that 2 liters of $H_2$ will completely react with 1 liter of $O_2$ to create 2 liters of $H_2O$.

3. Gas Law and Reaction Volumes: With the ideal gas law, you can change moles into volume and the other way around. If you know how many moles of a gas you have, you can easily find its volume using this formula:

   $V = nRT/P$

   In this formula, $V$ is volume, $n$ is the number of moles, $R$ is the ideal gas constant, and $P$ is pressure.

These examples show how useful stoichiometric calculations can be for gas reactions. They help us predict what will happen in real-life situations.