A science educator explains pH, defined as -log[H⁺]. If a solution has hydrogen ion concentration of 1 × 10⁻⁵ M, what is its pH?

["Understanding pH in Simple Terms: A Science Educator’s Guide", "pH is a fundamental concept in chemistry and environmental science, providing a straightforward way to measure how acidic or basic a solution is. Represented by the symbol pH, this scale ranges from 0 to 14, with 7 being neutral—like pure water—while numbers below 7 indicate acidity and above 7 indicate alkalinity. But what exactly does pH mean?", "At its core, pH is defined as the negative logarithm (log) of the hydrogen ion concentration [H⁺], expressed mathematically as:", "[\n\ ext{pH} = -\log{[H^+]}\n]", "This logarithmic scale compresses the wide range of ion concentrations into a manageable 0–14 scale. Because pH is logarithmic, each unit change represents a tenfold difference in H⁺ concentration. For example, a solution with pH 4 is ten times more acidic than one at pH 5.", "Let’s apply this to a common example:\nImagine a solution with a hydrogen ion concentration of [H⁺] = (1 \ imes 10^{-5}) moles per liter. To calculate the pH, plug this value into the formula:", "[\n\ ext{pH} = -\log{(1 \ imes 10^{-5})}\n]", "Using logarithmic rules, this simplifies to:", "[\n\ ext{pH} = -(-5) = 5\n]", "So, a solution with [H⁺] = (1 \ imes 10^{-5}) M has a pH of 5, classifying it as slightly acidic.", "Understanding pH and how to calculate it helps in many real-world scenarios—from testing soil quality in agriculture to monitoring water safety and optimizing chemical reactions in labs. It’s a key tool that makes complex chemical behaviors accessible and applied.", "Bottom line: If you ever measure hydrogen ion concentration, remembering the pH formula (-\log{[H⁺]}) lets you quickly determine how acidic or basic a solution truly is. Whether in classroom experiments or environmental science, pH remains an essential bridge between numbers and chemistry."]