A day of pH

Playing with pH: making it real

pH is a big deal in biology. But it can be dull and hopelessly abstract when the focus is the formula. The experiments below are designed to allow students to experience the reality of the "pouvoir d' hydrogen" (power of hydrogen; a handy mnemonic for pH, and actually the root of the abbreviation!). The 'red cabbage indicator' is an easy to make solution (basically cabbage + water + blender) that shows delightful colors and can be used to indicate a huge pH range. 'Miraculous lemonade' combines a pH-influenced protein (miraculin) with lemons. Lemons are nasty-bitter on their own, but abundant protons (H+; acidic pH) tweaks miraculin sitting on taste receptors to 'sense' sugar--making no-cal lemonade right in your mouth!

pH is often critical in biology, from amplifying hemoglobin's "bind in the lungs/release in the tissues" O2 behavior to the flu virus' clever 'Trojan horse' strategy.

Item Lab investigation Brief description Features
3 Colored cabbage red/purple cabbage contains a pH indicator with a remarkable range. With a simple blending-boiling procedure you get an indicator that can go from bright lime green to purple! Cabbage color chem
5 Miraculous lemonade An oral pH experiment comparing before (lemon only) and after (suck on a miraculin tablet) with the later producing a delicious, sugar-free lemonade!