Question

A scientist measures the pH of some rainwater and finds that it is acidic
Which pH corresponds with the acidic quality of the rainwater?
a) 6
b) 7
c) 8
d) 9

Answer 1

what's the definition of an acidic pH?

Answer 2

a) 6

Answer 3

pH is just shorthand for talking about a negative exponent on a 10 representing the concentration of H+. \[pH=4 \\= 10^{-4} \frac{mols \ H^+}{Liters}\] Remember, since negative exponents are the same thing as dividing, the larger the pH is, the smaller the concentration will be. However, the more acidic something is, the larger the concentration of H+ will be, so you can clearly see that \[\Large \frac{1}{10^3} > \frac{1}{10^6}\] since a one thousandth is larger than a millionth! This is why we say pH of 3 is more acidic than a pH of 6.