During the process of making cake, there is an important chemical reaction that is involved that determines if your cake will rise, aka, if your cake will look really like a “cake” – all puff up!
This is due to the chemical reaction between the Baking Soda (which contains Sodium Hydrogencarbonate) and the acid, to form carbon dioxide (CO2):
Sodium Hydrogencarbonate + Acid -> Sodium Salt + Carbon Dioxide + Water
Baking soda and the acidic component such as yoghurt, lemon juice, vinegar or sour cream must be added and mixed into the pastry mix. Carbon dioxide is then released by the reaction, but gets trapped in the mix, and causes the cake to rise. This reaction produces your light and delicious pastries.