|MadSci Network: Chemistry|
There is not much of a choice when it comes to harmless acid, available as household material. The most commonly used one is the acetic acid, which is contained in the vinegar. Other options are the citric acid and the tartaric acid, which sometimes could also be found in the kitchen. The last two acids, however, are crystal compounds and should be dissolved in water prior to use. The best way to test how much acid is neutralized by an antacid is to add some type of indicator to the antacid and then, with good stirring, to add drops of the acid until the indicator changes it's colour. At this point you should write down the amount of the used acid. This procedure is known as "titration" and is used by scientists to determine how much acid or base is contained in an object. Finding a proper indicator at home could be difficult. The evolution of gas from some antacids, however, could serve as an indication of the neutralisation process - in such case the acid is added until the evolution of the gas stops. A typical example is the reaction, which takes place when you mix baking soda (a kind of antacid) and vinegar: NaHCO3 + CH3COOH ---> CH3COONa + H2O + CO2 The gas that evolves is carbon dioxide (CO2). I remember having a lot of fun with this reaction when I was a kid. :-)
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