The Chemistry of Pop Rocks
Pop Rocks were created by William A. Mitchell in 1956. Even though they were created then, the candy was not introduced till the early 1970’s, because the FDA delayed approval. They were afraid to allow Pop Rocks to be sold, since it was mainly carbon dioxide. Finally, the patent was granted in 1968 (History 1). The patent number is 4289794. The patent is actually for the way they make the candy and not for the candy itself (Pop Rocks 1).
Usually when making hard candy, the sugar is heated until the impurities leave the mixture, but Pop Rocks are made differently than most hard candies, which contributes to the ability to “pop” (Pop Rocks 1). To make Pop Rocks you first mix sugar, milk sugar, corn syrup, and artificial flavoring. Then heat it at 300 degrees Fahrenheit until a syrup consistency is formed. Next, you stretch out the mixture and pressurize 600 psi (pounds per square inch) of carbon dioxide into the candy (How Are 2). This pressure is 40 times stronger than Earth’s atmospheric pressure (Pop Rocks 1). While the sugar is heated and pressurized the carbon dioxide gets trapped throughout the mixture. This causes it to form tiny bubbles that are suspended in the candy (How Are 2). So, you’re wondering how does the way it is made make it “pop”? Well, the candy melts and releases the carbon dioxide. So, the “pop” in your mouth is the 600 psi of carbon dioxide being released from each bubble (How do 1)! Since the pressure inside is so high compared to that outside, it rushes out to balance the pressure. Also, when you put the Pop Rocks in, there is a combination reaction occurring in your mouth. This happens when the heat of your mouth starts to melt the Pop Rocks. This weakens the walls of it and makes it harder to hold the carbon dioxide within the bubbles. The heat of your mouth also makes the carbon dioxide expand. This is a combination reaction between carbon dioxide and heat. With the weak wall...