Chemistry of Soda

|
chemistry of soda

Hopewell Valley Student Podcasting Network

Chemistry Connections

Chemistry of Soda

Episode #8  

Welcome to Chemistry Connections, my name is Neha and Nikhil and we are your hosts for episode #8 called Chemistry of Soda. Today we will be discussing basically that: the chemistry involved in soda.

Segment 1: Introduction to Soda

  • Soda is a fizzy beverage that people love to drink, ourselves included
  • There are many different kinds of soda. To name a couple: 
  • Coke
  • Fanta
  • Root beer
  • Pepsi 
  • And more
  • You can find it at any local grocery store
  • It is an enjoyable drink due to its carbonation and the sting it has on your tongue, which we will go into depth about shortly

Segment 2: The Chemistry Behind Soda

Topic 1: Equilibrium

  • First, let’s talk about the fizz in soda
  • Citric acid reacts with the carbonate in bicarbonate of soda to form carbon dioxide gas 
  • These bubbles of carbon dioxide gas are what make your drink fizzy
  • These molecules of carbon dioxide are thoroughly mixed and dissolved into the water in the soda pop
  • This is known as carbonation
  • Regarding carbonation, it is important to note: 
  • Carbon dioxide doesn’t easily dissolve in water under everyday conditions
  • Manufacturers have to increase the pressure in the can and keep it at a low temperature so water molecules can trap lots of carbon dioxide molecules
  • They also use pressure to put more gas in water than it could normally hold at that temperature
  • Therefore, if the soda can warms up a bit or the can is shaken, pressure goes up and extra gas is ready to come up
  • So opening the can releases pressure, and soda shoots out
  • This is why the can is sealed so that it is airtight. That way, the inside of the can maintains enough pressure to prevent extra carbon dioxide molecules from escaping
  • Talking about the can being sealed airtight, inside the can, carbon dioxide exists in two forms: some dissolves in water and some sits in gas form between the top of the can and the liquid
  • When carbon dioxide dissolves in water, water and gaseous carbon dioxide react to form a dilute solution of carbonic acid (H2CO3)
  • This reaction is reversible
  • When the can of soda is sealed, the high pressure inside the can forces the chemical reaction to the right (forward reaction)
  • This forward reaction continues until equilibrium is reached
  • However, once you open can, pressure is released and the reaction shifts to the left (so reverse reaction occurs)
  • In the reverse reaction, water and carbon dioxide are formed
  • This is because the gaseous carbon dioxide at the top of the can escapes when you open the can
  • The can is no longer under pressure if it is open, so dissolved carbon dioxide starts coming out of the solution (reverse reaction)
  • Bubbles form which release the carbon dioxide into the air
  • The escaping carbon dioxide lowers the concentration of carbon dioxide in the drink, so carbonic acid turns back to carbon dioxide and water which results in a new eqm
  • Now that we’re on the topic of bubbles that release carbon dioxide, let’s talk about the fizz of soda going away with time
  • I think it’s known to most people, excluding Nikhil, that fizzy soda tastes better than flat soda
  • In a fizzy drink, dilute carbonic acid creates a slight burning sensation on your tongue, which is enjoyable to some
  • This doesn’t happen with a flat drink though
  • Let’s start with how the drink becomes flat
  • If you open a soda can or bottle, the carbon dioxide begins to come out of the soda and into the air
  • Eventually, enough carbon dioxide will come out and the soda will become flat
  • When soda is flat, carbon dioxide continually escapes which is why there is no stinging sensation when soda is flat
  • Let’s recall the reaction from earlier where water and carbon dioxide react to form carbonic acid
  • As carbon dioxide bubbles away from liquid, the reactants and products move again towards equilibrium which causes the reverse reaction to take over since carbon dioxide, a reactant, is going away so the reaction proceeds in that direction to create more of it
  • This causes carbonic acid concentration to get lower and lower
  • Therefore, as the amount of carbonic acid in the beverage goes down, so does the soda’s ability to bring about the tingling sensation on your tongue

Topic 2: Acidity/pH

  • Now that we’ve talked about carbonic acid, let’s talk about other acids in soda
  • Phosphoric acid and citric acid are added as preservatives and flavor enhancers
  • Citric acid specifically can bind to calcium and leach it out of teeth, which is dangerous
  • Every soda on the market has a pH below 4, most between 2.5 to 3.5
  • The acidic pH of soda makes it dangerous for teeth
  • This is because acid is an instrumental part of the cavity process
  • The acidic pH of soda gives bacteria even more power to cause cavities by lowering the pH in the mouth and weakening enamel, 
  • Eventually, the enamel gets weak to the point where it cannot fight the acid attacks of bacteria well
  • Sugar in soda also feeds bacteria, which produce acid that dissolves enamel
  • These sugars in soda include a mixture of a sugar called glucose and another called fructose
  • These wo sugars attach to each other to make another sugar called sucrose
  • Anyway, back to the acidity of soda
  • The acidity of soda and absorption of carbon dioxide both can also cause a significant decrease in blood pH
  • This lower blood pH can possibly be associated with many diseases (including incurable cancer) because the body needs an alkaline environment for good health

Segment 3: Personal Connections

  • Soda is one of my favorite drinks (in my top 3)
  • So we thought it would be cool to take a dive into the chemistry behind soda, especially with the fizz since Neha likes fizzy soda but Nikhil does not
  • It was interesting to find out how the fizz works and why it fades away as time goes on
  • We really just chose it because it was a fun topic and soda is still something we drink weekly so it kind of is still a big part of our lives, even if it isn’t in a significant way

Thank you for listening to this episode of Chemistry Connections. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. 

Sources:

https://www.york.ac.uk/res/sots/activities/itsagas.htm#:~:text=The%20citric%20acid%20reacts%20with,what%20make%20your%20drink%20fizzy. 

https://www.acs.org/education/whatischemistry/adventures-in-chemistry/secret-science-stuff/soda-pop.html

https://letstalkscience.ca/educational-resources/stem-in-context/chemistry-pop  

http://ijariie.com/AdminUploadPdf/Chemistry_of_Soft_Drinks_ijariie11653.pdf

https://www.prodentcare.com/blog/why-soda-is-terrible-for-your-teeth#:~:text=What%20makes%20soda%20acidic%3F,as%20preservatives%20and%20flavor%20enhancers. 

https://www.premierdentalohio.com/blog/effects-of-drinking-pop-soda-on-dental-health#:~:text=Acidic%20pH,battery%20acid%20is%20about%201.0. 

https://www.medindia.net/patients/lifestyleandwellness/colas-are-bad-for-health-in-the-long-run.htm#:~:text=Carbon%20dioxide%20is%20the%20end,the%20blood%20making%20it%20acidic. 

Music Credits

Warm Nights by @LakeyInspired 

Subscribe to our Podcast

Connect with us on Social Media

Learn about soda (or pop) and some of the chemistry behind this fizzy wonder drink.

About the author, Hopewell Valley Student Publications Network

The Hopewell Valley Student Publications Network was created to empower students to become content creators in a digital-rich world. The views and opinions expressed within the digital content are the views of the content creators.

Tagged