Ph Calculator

pH Calculator

[H⁺] – Hydrogen Ion Concentration [OH⁻] – Hydroxide Ion Concentration

Results

pH: N/A

pOH: N/A

[H⁺] Concentration: N/A M

[OH⁻] Concentration: N/A M

Solution Type: N/A

function calculatePH() { var concentrationValue = parseFloat(document.getElementById("concentrationValue").value); var ionType = document.getElementById("ionType").value; if (isNaN(concentrationValue) || concentrationValue <= 0) { document.getElementById("calculatedPH").innerText = "N/A"; document.getElementById("calculatedPOH").innerText = "N/A"; document.getElementById("calculatedHPlus").innerText = "N/A"; document.getElementById("calculatedOHMinus").innerText = "N/A"; document.getElementById("solutionType").innerText = "Please enter a valid positive concentration."; return; } var pH, pOH, hPlus, ohMinus; // JavaScript's Math.log is natural log (base e). For base 10 log, use Math.log(x) / Math.LN10. if (ionType === "H_plus") { hPlus = concentrationValue; pH = -Math.log(hPlus) / Math.LN10; pOH = 14 – pH; ohMinus = Math.pow(10, -pOH); } else { // ionType === "OH_minus" ohMinus = concentrationValue; pOH = -Math.log(ohMinus) / Math.LN10; pH = 14 – pOH; hPlus = Math.pow(10, -pH); } var solutionDescription = ""; if (pH 7) { solutionDescription = "Basic (Alkaline)"; } else { solutionDescription = "Neutral"; } document.getElementById("calculatedPH").innerText = pH.toFixed(2); document.getElementById("calculatedPOH").innerText = pOH.toFixed(2); document.getElementById("calculatedHPlus").innerText = hPlus.toExponential(2); document.getElementById("calculatedOHMinus").innerText = ohMinus.toExponential(2); document.getElementById("solutionType").innerText = solutionDescription; }

Understanding pH: A Measure of Acidity and Alkalinity

The pH scale is a fundamental concept in chemistry, used to specify the acidity or basicity of an aqueous solution. It is a logarithmic scale that typically ranges from 0 to 14, where 7 is neutral. Values below 7 indicate acidity, while values above 7 indicate alkalinity (basicity).

What Does pH Stand For?

The term "pH" stands for "potential of hydrogen" or "power of hydrogen," referring to the concentration of hydrogen ions (H⁺) in a solution. The higher the concentration of H⁺ ions, the more acidic the solution, and the lower its pH value.

The pH Scale Explained

  • pH 7: Neutral – Pure water at 25°C has a pH of 7. At this point, the concentration of hydrogen ions ([H⁺]) is equal to the concentration of hydroxide ions ([OH⁻]), both being 1.0 x 10⁻⁷ M.
  • pH < 7: Acidic – Solutions with a pH less than 7 are acidic. The lower the pH, the stronger the acid. For example, lemon juice has a pH of around 2, and stomach acid can be as low as 1.
  • pH > 7: Basic (Alkaline) – Solutions with a pH greater than 7 are basic or alkaline. The higher the pH, the stronger the base. Examples include baking soda solution (pH 8-9) and household bleach (pH 12-13).

The Mathematics Behind pH

The pH of a solution is mathematically defined as the negative base-10 logarithm of the hydrogen ion concentration ([H⁺]), expressed in moles per liter (M):

pH = -log₁₀[H⁺]

Similarly, pOH is defined for hydroxide ion concentration ([OH⁻]):

pOH = -log₁₀[OH⁻]

At 25°C, the relationship between pH and pOH is constant:

pH + pOH = 14

These formulas allow us to calculate pH from ion concentrations, or vice versa, and to determine the acidity or alkalinity of a solution.

How to Use the pH Calculator

Our pH calculator simplifies these calculations for you. Follow these steps:

  1. Enter Concentration: Input the molar concentration (in Moles/Liter) of either the hydrogen ions ([H⁺]) or hydroxide ions ([OH⁻]) into the "Concentration" field.
  2. Select Ion Type: Choose whether the concentration you entered is for [H⁺] or [OH⁻] using the dropdown menu.
  3. Calculate: Click the "Calculate pH" button.

The calculator will instantly display the pH, pOH, the corresponding ion concentrations, and classify the solution as acidic, basic, or neutral.

Examples of pH Calculations:

  • Example 1: Strong Acid
    If you have a 0.01 M solution of a strong acid like HCl, the [H⁺] concentration is 0.01 M. Using the calculator:
    • Concentration: 0.01
    • Ion Type: [H⁺] – Hydrogen Ion Concentration
    • Result: pH = 2.00, Solution Type: Acidic
  • Example 2: Strong Base
    If you have a 0.001 M solution of a strong base like NaOH, the [OH⁻] concentration is 0.001 M. Using the calculator:
    • Concentration: 0.001
    • Ion Type: [OH⁻] – Hydroxide Ion Concentration
    • Result: pH = 11.00, Solution Type: Basic (Alkaline)
  • Example 3: Neutral Solution
    For pure water, [H⁺] is 1.0 x 10⁻⁷ M. Using the calculator:
    • Concentration: 0.0000001 (or 1e-7)
    • Ion Type: [H⁺] – Hydrogen Ion Concentration
    • Result: pH = 7.00, Solution Type: Neutral

This calculator is a useful tool for students, educators, and professionals in chemistry, biology, environmental science, and any field requiring quick and accurate pH determinations from concentration data.

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