Recently Paddy and myself have been doing quite a few reactions in plastic bottles for our chemistry demonstrations (http://bit.ly/2yCjdJ) and so we have been drinking a lot of bottled water. We had recently got our hands on some universal indicator, and thought we might use it to try and find out a bit more about the water we were drinking. Universal indicator is a few different indicators dissolved in ethanol, which is can be used to work out the pH of a solution. Don’t worry if you don’t have any of it, because it’s very easy to make indicators in the kitchen (http://bit.ly/s0EIm). Anything that is acid turns red when indicator is acid, and anything that is alkaline turns blue.
To start off we looked to see if there was any difference in sparkling water (12p a bottle from Tesco if you’re interested) that had just been opened and some which had been left open for a few days. The water on the left was the one that had been left open for few days and clearly contains less bubbles.
Both the solutions turned red on the addition of the indicator. This is to be expected as dissolving carbon dioxide in water produces carbonic acid. We couldn’t see any real difference in the colours, so we decided to move on.
Next we tested the difference in bottled still water and tap water. The bottled water (right) turned out to be pretty neutral, whilst the tap water (left) turned a nice green colour, meaning the water is slightly alkaline. This is an indication of hard water – to be expected living in the London area. A good explanation can be found here - http://bit.ly/39tP5b
Next we tested some washing powder. True to the advertising, Persil washing powder turned out to be pretty neutral. Flash floor cleaner on the other hand was almost as alkaline as caustic soda tested previously. A timely reminder of the importance of putting the correct cleaning agents in the washing machine, and the reason Paddy and myself still let our mums do our washing.
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