PH

Definition

pH is a measure of the acidity or alkalinity of a solution, defined as the negative logarithm (base 10) of the hydrogen ion concentration. It ranges from 0 to 14, with lower values being more acidic and higher values more basic.

5 Must Know Facts For Your Next Test

1. The pH scale is logarithmic, meaning each whole number change represents a tenfold increase or decrease in hydrogen ion concentration.
2. A pH of 7 is considered neutral, which is the pH of pure water at 25°C.
3. pH can be calculated using the formula $\text{pH} = -\log_{10}[H^+]$ where $[H^+]$ is the hydrogen ion concentration in moles per liter.
4. In algebraic terms, if you know the pH value, you can find $[H^+]$ using exponential functions: $[H^+] = 10^{-\text{pH}}$.
5. The properties of logarithms such as product, quotient, and power rules are essential when solving pH-related problems.

Review Questions

• What does a pH value indicate about a solution's acidity or alkalinity?
• How do you calculate the hydrogen ion concentration from a given pH value?
• What logarithmic property would you use to solve for pH when given a product of concentrations?

Related terms

Logarithm:

A mathematical function that determines how many times one number must be multiplied by itself to obtain another number. Expressed as $\log_b(a)$.

Exponential Function:

A function in which an independent variable appears in the exponent. Commonly expressed as $f(x) = b^x$.

Hydrogen Ion Concentration: The amount of hydrogen ions present in a solution, typically expressed in moles per liter ($[H^+]$). Directly related to the solution's pH.