Logarithmic Applications: PH
By Jordan and Danielle
pH= - log[H+]
What does that mean?
pH and Uses of Log()
How much less acidic is coffee with a pH of 5?
2= - log [H+]
-2= log [H+]
H+=o.o1 Hydrogen Ion concentration
* Remember you are subtracting a negative log so it is added.
Lemon juice pH - coffee pH = - log(.01) + log(.00001)
Difference in pH = log(.01/.00001)
-3 = log(.01/.00001)
Lemon juice is a 1000 times stronger acid than coffee. Because 10^-3 = 1000
Lemon Juice pH = X
X = -Log(.01)
-X = Log(.01)
Log(.01) = -2
-X = -2 so X = 2
We know from above that consecutive pH measurements increase 10 times in acidity per unit on the scale. So the pH of battery acid, 10 times less acidic, would be 3.