What is a 'bath bomb?' What reactions are involved?
A bath bomb is essentially composed of, among other things, a base and an acid. In this case, the citric acid is the acid, and the sodium bicarbonate acts as the base. Therefore, a bath bomb is basically a neutralization reaction that is triggered by contact with water.
The cornstarch is added into the bath bomb to ensure that the acid and base do not react until the bath bomb comes into contact with water.
When this bath bomb is dropped into water, the solid particles holding the shape of the bath bomb are dissolved, and the acidic ions and basic ions are allowed to disperse. During this process, these ions have a high chance of collision and when they collide, they neutralize and create the 'fizzing' reaction observed (carbon dioxide production). This part of the reaction produces carbon dioxide gas, which is why bubbles are formed. Then, the olive oil reacts with the base to form soap and glycerol - a substance that is very healthy for your skin.
The cornstarch component of the bath bomb also disperses into the water, and is healthy for the skin.
There are three major reactions observed during the production and use of this product, which are discussed below.
The cornstarch is added into the bath bomb to ensure that the acid and base do not react until the bath bomb comes into contact with water.
When this bath bomb is dropped into water, the solid particles holding the shape of the bath bomb are dissolved, and the acidic ions and basic ions are allowed to disperse. During this process, these ions have a high chance of collision and when they collide, they neutralize and create the 'fizzing' reaction observed (carbon dioxide production). This part of the reaction produces carbon dioxide gas, which is why bubbles are formed. Then, the olive oil reacts with the base to form soap and glycerol - a substance that is very healthy for your skin.
The cornstarch component of the bath bomb also disperses into the water, and is healthy for the skin.
There are three major reactions observed during the production and use of this product, which are discussed below.
Reaction During the Production of the Bath Bomb
Esterification Reaction
First of all, before the bath bomb can be made, the ester must be made. The ester can be made from an esterification reaction between a carboxylic acid and an alcohol. Since we are required to create the ester from two alcohols, one of these alcohols needs to be converted into a carboxylic acid first.
Desired ester: Isobutyl Propionate
Carboxylic acid required: Propanoic acid
Alcohols initially required: Isobutanol, Propan-1-ol
After the above reaction, we have one carboxylic acid (propanoic acid) and one alcohol (isobutanol) that will react together in the next step to create the desired ester.
In the above reaction, when proanoic acid and isobutanol are reacted together, they undergo esterification and produce water and isobutyl propionate (the ester responsible for the rum fragrance).
First of all, before the bath bomb can be made, the ester must be made. The ester can be made from an esterification reaction between a carboxylic acid and an alcohol. Since we are required to create the ester from two alcohols, one of these alcohols needs to be converted into a carboxylic acid first.
Desired ester: Isobutyl Propionate
Carboxylic acid required: Propanoic acid
Alcohols initially required: Isobutanol, Propan-1-ol
- Propan-1-ol + Reactive oxygen atom --------> Propanoic acid + H2O
- CH3-CH2-CH2-OH + {O} --------> CH3-CH2-COOH + H-O-H
- 7 C3H8O + 6 {O} --------> 3 C7H14O2 + 7 H2O
After the above reaction, we have one carboxylic acid (propanoic acid) and one alcohol (isobutanol) that will react together in the next step to create the desired ester.
- Propanoic acid + Isobutanol --------> Isobutyl Propionate + H2O
- CH3-CH2-COOH + (CH3)2-CH-CH2-OH --------> CH3-CH2-CH2-CO(=O)-CH2-CH(CH3)-CH3 + H-O-H
- C3H6O2 + C4H10O --------> C7H14O2 + H2O
In the above reaction, when proanoic acid and isobutanol are reacted together, they undergo esterification and produce water and isobutyl propionate (the ester responsible for the rum fragrance).
Reactions During the Contact with Water
When utilizing this bath bomb, there are two reactions that were observed:
Saponification Reaction
A saponification reaction is a reaction between a fatty ester and a base that creates soap and a glycerol. A soap is basically just a salt of an alkali metal - which, in my bath bombs, is sodium.
In this bath bomb, the olive oil acts as the fatty ester because it is made up of triglycerides, and the base is sodium bicarbonate. The sodium bicarbonate breaks the bonds of the olive oil ester and releases the fatty acid salt (in other words, soap!) and glycerol (a very efficient skin moisturizer) into the water, which makes the water soapy and is responsible for the cloudiness.
The saponification reaction that occurs when this bath bomb is dropped into water is:
(NOTE: The exact chemical reaction could not be determined due to the chemical composition of olive oil being split into separate triglycerides and lipids, therefore the general chemical equation for a triglyceride was used to react with sodium bicarbonate)
As seen in the products, the 'RCOO-Na' is the chemical equation of the resulting soap, and the other is the chemical equation of the glycerol.
Neutralization (Gas-Producing Reaction)
A neutralization reaction is when an acid and a base react together to neutralize the pH level of the solution; producing water and a salt. In this bath bomb, the reaction between the acid and the base produce a salt, water, and also a carbon dioxide gas (indicating that there was some fizzing involved in the reaction process - producing a gas)
The neutralization reaction that occurs when this bath bomb is dropped into water is:
As seen in the products, this is the gas-producing reaction responsible for the fizzing experienced when the bath bomb is dropped into the water.
- A saponification reaction
- A gas-producing reaction
Saponification Reaction
A saponification reaction is a reaction between a fatty ester and a base that creates soap and a glycerol. A soap is basically just a salt of an alkali metal - which, in my bath bombs, is sodium.
In this bath bomb, the olive oil acts as the fatty ester because it is made up of triglycerides, and the base is sodium bicarbonate. The sodium bicarbonate breaks the bonds of the olive oil ester and releases the fatty acid salt (in other words, soap!) and glycerol (a very efficient skin moisturizer) into the water, which makes the water soapy and is responsible for the cloudiness.
The saponification reaction that occurs when this bath bomb is dropped into water is:
(NOTE: The exact chemical reaction could not be determined due to the chemical composition of olive oil being split into separate triglycerides and lipids, therefore the general chemical equation for a triglyceride was used to react with sodium bicarbonate)
- Ester (fatty triglyceride) + Base --------> Soap + Glycerol
- Olive oil + Sodium hydrogen carbonate --------> Sodium salt + Glycerol
- Oleic acid + Sodium hydrogen carbonate --------> Sodium salt + Glycerol
- RCOOCH2-CH(OOCR)-CH2OOCR + NaHCO3 --------> RCOO-Na + HOCH2CH(OH)CH2OH
As seen in the products, the 'RCOO-Na' is the chemical equation of the resulting soap, and the other is the chemical equation of the glycerol.
Neutralization (Gas-Producing Reaction)
A neutralization reaction is when an acid and a base react together to neutralize the pH level of the solution; producing water and a salt. In this bath bomb, the reaction between the acid and the base produce a salt, water, and also a carbon dioxide gas (indicating that there was some fizzing involved in the reaction process - producing a gas)
The neutralization reaction that occurs when this bath bomb is dropped into water is:
- Base + Acid --------> Gas + Salt + Water
- Sodium bicarbonate + Citric Acid --------> Carbon dioxide + Sodium citrate + Water
- 3 NaHCO3 + C6H8O7 --------> 3 CO2 + C6H5Na3O7 + 3 H2O
As seen in the products, this is the gas-producing reaction responsible for the fizzing experienced when the bath bomb is dropped into the water.
Safety Concerns
A slight safety concern regarding the use of these bath bombs is if a consumer is allergic to any of the ingredients, it may hurt them. For example, if someone is allergic to starches, this bath bomb would not be recommended. Also, even though these bath bombs are not toxic, ingesting any of the water could possibly lead to illness. Also, getting water in the eyes may cause irritation and should be avoided. It should also be noted that the cornstarch content of this bath bomb may lead to some skin infections over time if you are susceptible to them.
Analysis of Trial Reaction
To test the predicted reactions discussed above and ensure the product was fully functional, a small sample of the bath bomb was tested in warm water. The resulting reactions were analyzed to make sure that the predictions were correct, and they absolutely were.
As soon as the bath bomb was placed in a beaker of water, it started fizzing and releasing it's contents into the water. This was confirmed because according to predictions, the neutralization reaction would happen and carbon dioxide gas would be released in the form of bubbles. This gas-release reaction was observed in the beaker with the bath bomb sample, proving that the neutralization reaction did occur.
Also, the saponification reaction was also successful because the water in the beaker turned cloudy, the sign that a form of soap is present. The water would also feel as if it is 'soapy' if one was to touch the water.
Next, we know that the contents of the bath bomb were released into the beaker. This was evident because when the contents of the beaker were sniffed, it produced the pleasurable rum scent that was included via the ester. Also, the food coloring dissolved into the water and changed the color to green.
In conclusion, the trial reaction of the bath bomb succeeded and is ready to be sold and used by consumers.
As soon as the bath bomb was placed in a beaker of water, it started fizzing and releasing it's contents into the water. This was confirmed because according to predictions, the neutralization reaction would happen and carbon dioxide gas would be released in the form of bubbles. This gas-release reaction was observed in the beaker with the bath bomb sample, proving that the neutralization reaction did occur.
Also, the saponification reaction was also successful because the water in the beaker turned cloudy, the sign that a form of soap is present. The water would also feel as if it is 'soapy' if one was to touch the water.
Next, we know that the contents of the bath bomb were released into the beaker. This was evident because when the contents of the beaker were sniffed, it produced the pleasurable rum scent that was included via the ester. Also, the food coloring dissolved into the water and changed the color to green.
In conclusion, the trial reaction of the bath bomb succeeded and is ready to be sold and used by consumers.