Calculate the rate of diffusion for multiple samples or petri dishes simultaneously.
Sample / Dish ID
Distance Traveled (mm)
Time Elapsed (min)
Calculated Rate
millimeters
minutes
–
millimeters
minutes
–
millimeters
minutes
–
millimeters
minutes
–
millimeters
minutes
–
Please ensure Time is greater than 0.
function calculateDiffusionRates() {
var hasError = false;
// Loop through 5 rows
for (var i = 1; i <= 5; i++) {
var distInput = document.getElementById('dist' + i);
var timeInput = document.getElementById('time' + i);
var resultCell = document.getElementById('res' + i);
var distance = parseFloat(distInput.value);
var time = parseFloat(timeInput.value);
// Clear previous styles
resultCell.innerHTML = "-";
resultCell.style.color = "#27ae60";
distInput.style.borderColor = "#ccc";
timeInput.style.borderColor = "#ccc";
// If inputs are empty, skip this row without error
if (distInput.value === "" && timeInput.value === "") {
continue;
}
// Validation logic
if (isNaN(distance) || isNaN(time)) {
resultCell.innerHTML = "Invalid Input";
resultCell.style.color = "#c0392b";
continue;
}
if (time 0″;
resultCell.style.color = "#c0392b";
timeInput.style.borderColor = "#c0392b";
hasError = true;
continue;
}
// Calculation: Rate = Distance / Time
var ratePerMin = distance / time;
var ratePerHour = ratePerMin * 60;
// Formatting result
// Displaying in mm/min and mm/hr for convenience
resultCell.innerHTML = ratePerMin.toFixed(4) + " mm/min(" + ratePerHour.toFixed(2) + " mm/hr)";
}
var errorMsg = document.getElementById('globalError');
if (hasError) {
errorMsg.style.display = 'block';
} else {
errorMsg.style.display = 'none';
}
}
function resetCalculator() {
for (var i = 1; i <= 5; i++) {
document.getElementById('id' + i).value = "";
document.getElementById('dist' + i).value = "";
document.getElementById('time' + i).value = "";
document.getElementById('res' + i).innerHTML = "-";
document.getElementById('dist' + i).style.borderColor = "#ccc";
document.getElementById('time' + i).style.borderColor = "#ccc";
}
document.getElementById('globalError').style.display = 'none';
}
Understanding Diffusion Rate Calculation
Diffusion is the net movement of anything (typically atoms, ions, molecules, energy) from a region of higher concentration to a region of lower concentration. In laboratory settings, such as microbiology or chemistry, calculating the diffusion rate is crucial for analyzing the effectiveness of substances, the permeability of membranes, or the motility of organisms.
The Diffusion Rate Formula
For most basic experimental setups, such as measuring the zone of inhibition on an agar plate or the travel of a dye front, the average diffusion rate is calculated using a linear relationship relative to time:
Rate = Distance Traveled / Time Elapsed
Where:
Distance Traveled (mm): The measurement from the center of the application point to the edge of the diffusion zone.
Time Elapsed (min): The duration between the start of the experiment and when the measurement was taken.
Applications of this Calculator
This tool is designed to handle multiple entries simultaneously ("Batch Processing"), making it ideal for:
Agar Gel Diffusion: Comparing how fast different antibiotics or chemicals diffuse through agar.
Dye Migration Studies: Tracking the velocity of dye particles in various solvents.
Osmosis Experiments: Measuring the rate of fluid movement across semi-permeable membranes if distance correlates to volume change.
How to Measure Accurately
To ensure your diffusion rate calculations are valid, follow these standard practices:
Measure from the exact center of the well or disc.
Ensure the time is recorded in minutes. If you have hours, convert them (e.g., 2 hours = 120 minutes).
Keep environmental variables constant (Temperature and Pressure), as these significantly alter diffusion coefficients.
Interpreting the Results
The calculator provides the rate in millimeters per minute (mm/min). A higher value indicates a faster rate of diffusion. This usually implies a smaller molecular weight, a less viscous medium, or a higher temperature. A lower rate suggests large molecules or a highly viscous resistance in the dish.