In this paper you learn about the reactions that occur between backing soda and lemon juice. We will also describe what is occurring with the molecules on a molecular level. Lastly we will explain what chemical bonds are formed and or broken when lemon juice and backing soda.
Observations of the Reactants
When most people hear baking soda they think of the bright orange box sitting in their pantry or refrigerator soaking up the foul odors that have come about from the onions or fish. Some may think of pancakes or baking a cake. Baking powder is a fine white substance with the consistency of powdered sugar. Baking soda is a chemical base. Another substance most people do not recognize as a chemical in their household is Lemon Juice. This is a liquid mixture of water and citric acid. Its color is mildly foggy and a pale yellow. Lemon juice is a chemical acid and when mixed with a base like baking soda creates a reaction.
Reactions that occur
Mixing lemon juice with baking soda gives you a chemical reaction. The lemon juice contains citric acid. The citric acid from the lemon juice will donate a hydrogen ion (H+) to the bicarbonate or baking soda (NaHCO3). When the bicarbonate is mixed into solution, the bicarbonate acts as a base and takes the H+ ion from the citric acid to form carbonic acid (H2CO3) and carbon dioxide (CO2). Whenever a chemical reaction produces gas, it will be highly favored due to its large increase in entropy associated with the gas formation. In this reaction, you will notice the solution bubbling and foaming due to the CO2 production. The reaction of lemon juice and baking soda is as follows:
C6H8O7 + 3NaHCO3 <—> Na3C6H5O7 + 3H2CO
Essentially, one molecule of citric acid will react with three molecules of sodium bicarbonate. This will form one molecule of sodium citrate and three molecules of carbonic acid. It is a very exothermic chemical reaction.
Baking soda or sodium bicarbonate is a salt while lemon juice is a citric acid. When combined, on a molecular basis, the acid in the lemon juice is able to lose a hydrogen (H+) ion while the sodium bicarbonate (NaHCO3) of the baking soda is able to gain an ion. Mixed in a solution, the NaHCO3 dissociates into a sodium (Na+) and bicarbonate (HCO3-) ion. The HCO3- then takes the H+ ion to form H2CO3 (carbonic acid).
Bonds that formed and broken
The bonds that are forming between the lemon juices and backing soda are polar covalent bonds. The bonds have an uneven electron share which is known as a dipole moment that makes them insoluble. Each the backing soda and the lemon juice have bonds that are broken. The bonds that are broken in the citric acid are when the H+ ions are taken away to form the H2CO3 and CO2. While this is happening the two molecules are sharing there atoms which is making then fight one another. So in return the baking soda does not naturalize the lemon juice like most acids and bases do. This is the violent bubbling reaction you see occur when the two are mixed.
Backing soda and lemon juice are two very few reactants that react the way they do. Normally a base and an acid turn neutral. This is not the case between these two chemicals. The molecules fight on another casing them to react violently resulting in the bubbling situation that is observer. As you have learned these two chemicals react in a way to form a gas called carbon dioxide. The color changed mildly to form a fogy white color. When it is compared on a pH level it is stronger than stomach acid. This experience has showed us that different reactants react in many different ways and that is why it is important to observe them many different items before make an assumption.
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Tro, N. J. (2009). Introductory chemistry. (3rd ed.). Upper Saddle River, NJ: Pearson/Prentice Hall.
What is the chemical equation for lemon juice and baking soda. (n.d.). Retrieved from http://wiki.answers.com/Q/What_is_the_chemial_equation_for_lemon_juice_and_baking_soda