Modeling with Exponential and Logarithmic Equations — Quiz
Question 15 • Mathematics III
The equation for the pH of a substance is pH is equal to negative log times open bracket cap h raised to the plus power close bracket , where H+ is the concentration of hydrogen ions. Which equation models the concentration of hydrogen ions open paren cap h raised to the plus power close paren of a solution whose pH is 7 point 2 ?
Answer
A
open bracket cap h raised to the plus power close bracket is equal to 10 raised to the negative 7 point 2 power
B
open bracket cap h raised to the plus power close bracket is equal to log 7 point 2
C
open bracket cap h raised to the plus power close bracket is equal to negative log 7 point 2
D
open bracket cap h raised to the plus power close bracket is equal to 10 raised to the 7 point 2 power
Explanation
Start with pH = −log[H+]. Substitute pH = 7.2 to get 7.2 = −log[H+], so log[H+] = −7.2. Rewriting in exponential form gives [H+] = 10^−7.2, which is choice A.
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