Water. Citric acid. Polar molecules. And why adding citrus fruits give water such a zing.
Want a zing on your tastebuds when you drink water? Why not just add some citrus fruits like lemons and limes, both of which have the highest citric acid content amongst fruits?
Citric acid has the formula C6H8O7. More importantly it contains O-H bonds. O-H bonds are interesting because the electrons on them are not evenly shared. There are more electrons on the oxygen atoms, giving them a partially negative charge. The hydrogen atoms thus have a partially positive charge. This distribution of charges makes citric acid a polar molecule.
Water is also a polar molecule, where the hydrogen atoms are partially positively charged (∂+) while the oxygen atoms are partially negatively charged (∂-). As a result …
“… the positive ends of water molecules are attracted to the negative areas of the citric acid molecules. The negative ends of water molecules are attracted to the positive areas of the citric acid molecules. These mutual attractions will overcome the attractions citric acid molecules have for other citric acid molecules, causing them to mix thoroughly in the water and dissolve.” (Source: American Chemical Society)
With such thorough mixing and dissolving, the citric acid gives our water a zing and makes for a great refreshing drink. And if we not only want a refreshing drink, but a sweet one as well, we can add sugar. Sugar and water also mix very well (partly because of O-H bonds too – read all about the science in the 1-Minute NomNom “Sucrose yet so far“).
Citric acid, water and sugar. If you have not already noticed (did you see what we did there?), that is simply the recipe for delicious homemade lemonade and limeade!
You might have noticed that restaurants sometimes put other fruits in the water they serve, such as apples or strawberries. Do these have a high enough citric acid content to give the water a zing (hint: check this)? This also gives you an idea what fruits to use if you are doing this at home!
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