After all the work you put into baking a cake, a sunken cake can be very disheartening. However, this can be avoided if you stay true to the recipe and use fresh ingredients.

If you, particularly, use baking soda or powder that has passed its prime, you won't get very many air bubbles in the mix, and your cake won't rise properly.

Baking soda and powder don’t spoil, so they are not dangerous to use when expired, but they do lose potency over time, especially when exposed to moist climates.

Baking powder is especially vulnerable because it already has an acid built in, and all it takes to start the bubbly reaction is a little bit of moisture from the air.