Ph Poh Calculations Worksheet

pH and pOH Calculation Worksheet Calculator

pH pOH Hydrogen Ion Concentration [H+] (mol/L) Hydroxide Ion Concentration [OH-] (mol/L)

function calculatePhPoh() { var type = document.getElementById("inputType").value; var val = parseFloat(document.getElementById("inputValue").value); var resultsDiv = document.getElementById("results"); var ph, poh, h, oh; if (isNaN(val) || val <= 0 && (type === 'h' || type === 'oh')) { alert("Please enter a valid positive number."); return; } if (type === "ph") { ph = val; poh = 14 – ph; h = Math.pow(10, -ph); oh = Math.pow(10, -poh); } else if (type === "poh") { poh = val; ph = 14 – poh; h = Math.pow(10, -ph); oh = Math.pow(10, -poh); } else if (type === "h") { h = val; ph = -Math.log10(h); poh = 14 – ph; oh = Math.pow(10, -poh); } else if (type === "oh") { oh = val; poh = -Math.log10(oh); ph = 14 – poh; h = Math.pow(10, -ph); } document.getElementById("resPh").innerText = ph.toFixed(4); document.getElementById("resPoh").innerText = poh.toFixed(4); document.getElementById("resH").innerText = h.toExponential(4) + " mol/L"; document.getElementById("resOh").innerText = oh.toExponential(4) + " mol/L"; var natureBox = document.getElementById("nature"); if (ph 7) { natureBox.innerText = "Basic (Alkaline) Solution"; natureBox.style.backgroundColor = "#74b9ff"; natureBox.style.color = "white"; } else { natureBox.innerText = "Neutral Solution"; natureBox.style.backgroundColor = "#55efc4"; natureBox.style.color = "#2d3436"; } resultsDiv.style.display = "block"; }

Understanding pH and pOH Calculations

In chemistry, the acidity or alkalinity of an aqueous solution is measured using the pH and pOH scales. These scales are logarithmic, meaning each whole number change represents a tenfold change in concentration. This pH and pOH calculations worksheet tool helps students and professionals quickly convert between ion concentrations and their logarithmic counterparts.

The Core Formulas

To solve any pH/pOH problem, you must remember four fundamental equations based on the self-ionization of water at 25°C:

• pH = -log[H+]
• pOH = -log[OH-]
• pH + pOH = 14
• [H+] × [OH-] = 1.0 × 10^-14

How to Use This Worksheet Tool

This calculator acts as a digital worksheet. If you know one of the four variables, you can find the other three instantly:

1. Identify your known: Look at your chemistry problem. Do you have the pH, the pOH, or a molar concentration?
2. Select the Input: Choose the corresponding label from the dropdown menu.
3. Enter the Value: Type in the number. For scientific notation like 1.0 × 10^-5, enter "1e-5".
4. Analyze the Nature: The tool will tell you if the resulting solution is Acidic, Basic, or Neutral based on a pH of 7.0.

Practical Example Calculations

Example 1: Finding pH from [H+]
If a solution has a Hydrogen ion concentration of 2.5 × 10^-4 M:
Calculation: pH = -log(2.5 × 10^-4) &approx; 3.60.
Result: The solution is acidic.

Example 2: Finding [OH-] from pH
If a solution has a pH of 9.5:
Calculation: pOH = 14 – 9.5 = 4.5.
Calculation: [OH-] = 10^-4.5 &approx; 3.16 × 10^-5 M.

Common Chemistry Tips

When working on your pH and pOH calculations worksheet, keep these rules of thumb in mind:

• The 14 Rule: pH and pOH always add up to 14 at standard temperature (25°C). If your sum is different, double-check your math!
• Significant Figures: In logarithms, only the digits to the right of the decimal point are significant. If your concentration has 2 significant figures (e.g., 1.2 × 10^-3), your pH should have 2 decimal places (e.g., 2.92).
• Inverse Operations: To reverse a pH calculation, use the "antilog" or 10^-pH function on your calculator.