Rate of Reaction Calculator
Calculate the average speed of a chemical reaction over time.
What is the Rate of Reaction?
In chemistry, the reaction rate refers to the speed at which a chemical reaction proceeds. It is typically expressed as the change in concentration of a reactant or a product per unit of time. Understanding the rate is crucial for industrial processes, pharmaceutical manufacturing, and environmental science.
The Formula Explained
To calculate the average rate of reaction, we use the following variables:
- Δ[Concentration]: The change in molarity. This is found by subtracting the initial concentration from the final concentration.
- Δt: The time elapsed during the reaction (usually measured in seconds).
Note: For reactants, the concentration decreases, leading to a negative change. However, reaction rates are conventionally expressed as positive values, so we multiply the result by -1. For products, the concentration increases, resulting in a positive rate naturally.
Example Calculation
Suppose you are monitoring the decomposition of Hydrogen Peroxide (H₂O₂). At time zero (t = 0s), the concentration is 1.00 M. After 100 seconds (t = 100s), the concentration drops to 0.75 M.
Step 1: Identify Δ[C] = 0.75 M – 1.00 M = -0.25 M.
Step 2: Identify Δt = 100s.
Step 3: Rate = -(-0.25 M / 100 s) = 0.0025 M/s.
Factors Influencing Reaction Rates
Several factors can speed up or slow down a chemical reaction:
- Concentration: Higher concentrations of reactants generally lead to more frequent collisions and a faster rate.
- Temperature: Increasing temperature adds kinetic energy, causing molecules to move faster and collide with more force.
- Surface Area: For solids, increasing the surface area (by crushing) allows more reactant particles to be exposed.
- Catalysts: These substances lower the activation energy required for the reaction without being consumed themselves.