Calculated Ph

Strong Acid (e.g., HCl, HNO₃) Strong Base (e.g., NaOH, KOH)

Calculation Results:

pH Value:

pOH Value:

[H⁺] Concentration: mol/L

[OH⁻] Concentration: mol/L

Nature:

function calculatePH() { var type = document.getElementById("substanceType").value; var conc = parseFloat(document.getElementById("concentration").value); var resultArea = document.getElementById("ph-result-area"); if (isNaN(conc) || conc <= 0) { alert("Please enter a valid concentration greater than 0."); return; } var ph, poh, hConc, ohConc; if (type === "strongAcid") { // For strong acids: [H+] = Molarity hConc = conc; ph = -Math.log10(hConc); poh = 14 – ph; ohConc = Math.pow(10, -poh); } else { // For strong bases: [OH-] = Molarity ohConc = conc; poh = -Math.log10(ohConc); ph = 14 – poh; hConc = Math.pow(10, -ph); } document.getElementById("displayPH").innerText = ph.toFixed(4); document.getElementById("displayPOH").innerText = poh.toFixed(4); document.getElementById("displayHPlus").innerText = hConc.toExponential(4); document.getElementById("displayOHMinus").innerText = ohConc.toExponential(4); var nature = ""; if (ph 7.5) nature = "Basic (Alkaline)"; else nature = "Neutral"; document.getElementById("solutionNature").innerText = nature; resultArea.style.display = "block"; }

Understanding Calculated pH

pH is a logarithmic measure of the hydrogen ion concentration in a solution. It determines how acidic or basic a substance is on a scale typically ranging from 0 to 14. A pH of 7 is considered neutral (like pure water), while values below 7 are acidic and values above 7 are alkaline or basic.

The Math Behind pH

The calculation is based on the negative logarithm (base 10) of the molar concentration of hydrogen ions ([H⁺]). The formula is expressed as:

pH = -log₁₀[H⁺]

Similarly, pOH measures the concentration of hydroxide ions ([OH⁻]). In any aqueous solution at 25°C, the relationship between pH and pOH is constant:

pH + pOH = 14

Calculation Example

If you have a 0.01 M solution of Hydrochloric Acid (a strong acid):

• Concentration [H⁺]: 0.01 mol/L (or 10⁻² M)
• pH Calculation: -log₁₀(0.01) = 2
• pOH: 14 – 2 = 12
• Result: Highly acidic solution.

Why Molarity Matters

Molarity (M) represents the number of moles of a solute per liter of solution. Since the pH scale is logarithmic, a change of one pH unit represents a tenfold change in ion concentration. For example, a solution with a pH of 3 is ten times more acidic than a solution with a pH of 4.

Strong vs. Weak Substances

This calculator is designed for strong acids and bases, which dissociate completely in water. For weak acids (like vinegar) or weak bases (like ammonia), additional data such as the acid dissociation constant (Ka) or base dissociation constant (Kb) would be required to perform an accurate calculation using the ICE table method.