A pH pHoem

For coffee it´s 5, for tomatoes it´s 4
While household ammonia´s 11 or more
It´s 7 for water if in a pure state
But rainwater´s 6, and seawater´s 8
It´s basic at 10, quite acidic at 2
And well above 7 when litmus turns blue
Some find it a puzzle-doubtless their fog
Has something to do with that negative log!
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NOTA: El presente poema no es de mi autoría sino que lo he copiado de la Internet desconociendo su autor original./I am not the author of this poem, I 've just copy-pasted it from a webpage from an unknown author.