We have recently become curious about the pH of carbonated water – the kind that only contains bubbles and flavor, but no extra sugar. In keeping with our natures, Ian & I have decided to run an experiment to find out. Here’s what we’re going to do.

Over time, as the carbonation in an open can of sparkling water escapes, the acidity of the beverage will move from more acidic towards more neutral.

2 Cans of La Croix lemon-flavored sparkling water, labeled A & B
Probe for measuring acidity
1 Straw
1 Timekeeping device
Materials for recording results

At time 0, open both cans. Taking care not to jostle can A, insert the probe into can A and measure and record the acidity.

Also not jostling can B, insert straw into can B and drink a small sip. Record qualitatively the perception of carbonation and acidity.

Note: two researchers can do these tasks separately, not sharing results, in an effort to remain blind.

After 5 minutes have elapsed, repeat measurements, both quantitative and qualitative, and record results.

Repeat measurements and recordings every 5 minutes until all carbonation has escaped from the cans, as reported by can B sample taster, or researchers run out of time and/or patience.

Analyze data.

Knowing that carbon dioxide is converted into carbonic acid in water (1), we hypothesized that acidity of a carbonated beverage would decrease (move towards neutral) as carbon dioxide gas was released from the liquid over time.

To be continued after study is complete.

We could use some help determining how long it would take for a can of sparkling water to go completely flat. Any thoughts, chemists or science-types? Also, any alternative hypotheses or suggestions for improving the methodology? We’re thinking of submitting our results, if significant, to the Journal of Carbonation Science, so we’d better get it right.

2 thoughts on “Evaluation of Relationship Between Carbonation and Acidity

  1. I’m no science geek but my experience with cans of coke is that the carbonation lasts longer than expected–maybe even up to 24 hours? I can’t really remember but it is in the hours category. Good luck with your experiment and subsequent publication!

  2. In our 9th grade science classes we allow 24 hours for all the fizz to dissipate before students measure the density of pop.

    If you use the LabQuest and pH probe, you can actually keep the device plugged in and program it to continue collecting data for days… then you can read (or print) data in tabular or graphical format or both!

    Have fun geeking out. I’ll bring the lab materials home tomorrow.

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