Chemical kinetics: Rate of Reaction

Understanding Rate of Reaction with Product Concentration

In chemical kinetics, the rate of reaction can be studied by observing the change in concentration of either reactants or products over time. While many reactions are tracked using the disappearance of reactants, in some cases, it is more convenient to follow the formation of products. This article explains how the concentration of products influences the rate of reaction, and includes an interactive example.

📈 What is Product Concentration?

Product concentration refers to the amount of product formed per unit volume during a chemical reaction. As the reaction proceeds, the concentration of the product increases, and we can use this change to determine the rate of the reaction.

📘 Rate of Reaction Formula (Product Based)

The average rate based on product concentration is given by:

Rate = Δ[Product] / Δt

📈 Graphical Analysis of Rate Laws

Rate of Reaction vs Concentration

🔢 Calculate Average Rate of Reaction

Initial Product Concentration [P]₁ (mol/L):

Final Product Concentration [P]₂ (mol/L):

Time Interval Δt (seconds):

🔬 Real-life Example

Suppose in a reaction forming oxygen gas, the concentration increases from 0.10 mol/L to 0.30 mol/L in 40 seconds. Using the formula:

Rate = (0.30 - 0.10) / 40 = 0.005 mol L⁻¹ s⁻¹

🧪 Conclusion

Tracking product concentration is a valuable approach in chemical kinetics, especially when reactant disappearance is difficult to observe. By using simple calculations and digital tools, students and chemists alike can understand reaction rates more easily and precisely.

🧪 Rate of Reaction Quiz

1. In a zero-order reaction, rate is:

Proportional to [A] Constant Proportional to [A]² Zero

2. If doubling [A] quadruples rate, the order is:

Zero First Second Third

3. What is the unit of rate constant for a first-order reaction?

mol⁻¹L·s⁻¹ s⁻¹ mol/L·s No units

4. Which graph shows a constant rate regardless of [A]?

First-order Second-order Zero-order All of them

📚 You may also like:

• Feasibility with Chemical Kinetics
• Average Rate of Reaction
• Empirical Formula: Concept and Calculation

📚 Related Chemistry Articles

Knowing pH Scale: Complete Guide

Color Change by Indicators in Solutions

Sulphuric Acid: Structure & Reactions

Empirical Formula: Definition and Steps

Feasibility with Chemical Kinetics

Rate of Reaction and Average Rate

React Fast! – Understand Rate of Reaction

👨‍🔬 Click "Start Reaction" and observe how fast Reaction A and B complete.
🧪 प्रतिक्रिया शुरू करें और देखें कौन सी तेजी से पूरी होती है: तेज़ (Fast) या धीमी (Slow)?

Reaction A (Fast)
e.g. HCl + Zn

Time: 0 sec

Reaction B (Slow)
e.g. Rusting Iron

Time: 0 sec

What Did You Learn?

Reaction A finished faster because it represents a fast reaction (e.g., acid reacting with metal). Reaction B is slower like rusting. This shows how reaction speed depends on:

• 🔼 Temperature
• 🎯 Concentration
• 🔬 Catalyst presence
• 📏 Surface area

Hindi: यह खेल दिखाता है कि रासायनिक अभिक्रियाओं की दर अलग-अलग हो सकती है। तेज़ प्रतिक्रिया में अधिक टकराव और ऊर्जा होती है।