How to Calculate the Instantaneous Rate of a Reaction
by
Instantaneous Reaction Rate Calculator
The instantaneous rate of a reaction at any given moment is the rate at which the reactants are consumed or products are formed at that specific point in time. It's often determined by finding the slope of the tangent line to the concentration-time curve at that point.
function calculateInstantaneousRate() {
var initialConcentration = parseFloat(document.getElementById("initialConcentration").value);
var finalConcentration = parseFloat(document.getElementById("finalConcentration").value);
var timeDifference = parseFloat(document.getElementById("timeDifference").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous result
if (isNaN(initialConcentration) || isNaN(finalConcentration) || isNaN(timeDifference)) {
resultDiv.innerHTML = "Please enter valid numbers for all fields.";
return;
}
if (timeDifference <= 0) {
resultDiv.innerHTML = "Time elapsed must be a positive value.";
return;
}
// The formula for average rate over a time interval is Delta[Reactant]/Delta[Time].
// For instantaneous rate, we approximate this with a small time interval.
// Rate = (Final Concentration – Initial Concentration) / Time Elapsed
// Note: For the rate of reactant consumption, this value will be negative.
// We often report the magnitude or the rate of product formation.
var rate = (finalConcentration – initialConcentration) / timeDifference;
if (rate < 0) {
resultDiv.innerHTML = "Approximate Instantaneous Rate of Reactant Consumption: " + rate.toFixed(5) + " mol/(L·s)";
resultDiv.innerHTML += "Approximate Instantaneous Rate of Product Formation: " + (-rate).toFixed(5) + " mol/(L·s)";
} else {
resultDiv.innerHTML = "Approximate Instantaneous Rate: " + rate.toFixed(5) + " mol/(L·s)";
}
}
.reaction-rate-calculator {
font-family: sans-serif;
padding: 20px;
border: 1px solid #ccc;
border-radius: 8px;
max-width: 500px;
margin: 20px auto;
}
.reaction-rate-calculator h2 {
text-align: center;
margin-bottom: 20px;
color: #333;
}
.reaction-rate-calculator p {
margin-bottom: 15px;
line-height: 1.6;
color: #555;
}
.input-group {
margin-bottom: 15px;
}
.input-group label {
display: block;
margin-bottom: 5px;
font-weight: bold;
color: #444;
}
.input-group input[type="number"] {
width: calc(100% – 20px);
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box;
}
.reaction-rate-calculator button {
display: block;
width: 100%;
padding: 12px;
background-color: #007bff;
color: white;
border: none;
border-radius: 4px;
font-size: 16px;
cursor: pointer;
transition: background-color 0.3s ease;
}
.reaction-rate-calculator button:hover {
background-color: #0056b3;
}
.result-display {
margin-top: 20px;
padding: 15px;
background-color: #e9ecef;
border: 1px solid #dee2e6;
border-radius: 4px;
text-align: center;
font-weight: bold;
color: #333;
}
.result-display p {
margin-bottom: 5px;
}