Beginner Topic 498 of 1102 Kinetics & Equilibrium
Rate vs Time Graphs
Concentration-time graphs show how reactants fall and products rise, with slope giving rate.
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In-depth explanation of Rate vs Time Graphs
Rate versus time graphs and concentration versus time graphs provide a direct visual picture of how a reaction proceeds. A concentration versus time graph shows reactant concentration falling and product rising, and the slope of the tangent to the curve at any time gives the instantaneous rate at that moment. The shape of the curve reveals the reaction order: for a first order reaction the concentration falls with decreasing slope, while for a zero order reaction the decline is a straight line of constant slope. Plotting the rate itself against concentration can also reveal the order directly. Graphs of this kind are the main data format in many kinetics experiments.
Going deeper: Rate vs Time Graphs
Key ideas: Reading graphs: for first order the concentration curve is exponential and a plot of rate against concentration is a straight line through the origin; for zero order the rate against concentration is flat; for second order the rate against concentration is a parabola. Tangent slopes at several times give rates, and log-log plots of rate against concentration give the order as slope.
Common mistakes and connections: Students confuse the graph of concentration against time with the graph of rate against time. A concentration decay is not a rate curve, and a steeper start does not imply a first order reaction without testing it. Another error is reading a tangent in the wrong direction for the product, whose graph rises. Related to average and instantaneous rate and integrated rate laws.
Visualization of Rate vs Time Graphs
The zero order line has constant slope, while the first order curve flattens as reactant is used up; the tangent slope at each time is the rate. The interactive lesson shows this as a live animation or chart.
Worked example and use case
The initial slope of a concentration versus time graph gives the initial rate of the reaction.
Frequently asked questions about Rate vs Time Graphs
What is Rate vs Time Graphs?
Concentration-time graphs show how reactants fall and products rise, with slope giving rate.
Is Rate vs Time Graphs a beginner, intermediate or advanced topic?
Rate vs Time Graphs is a beginner topic in Kinetics & Equilibrium. It needs no earlier chemistry lessons and is a good starting point.
What should I learn before Rate vs Time Graphs?
Study these earlier topics in Kinetics & Equilibrium first: Relaxation Methods, Flash Photolysis, Clock Reactions.
What comes after Rate vs Time Graphs?
The next topics in Kinetics & Equilibrium are Catalytic Converters and Inhibitors and Poisons.
Can I practise Rate vs Time Graphs with quizzes?
Yes. The interactive lesson includes a self-check question on Rate vs Time Graphs, and the Kinetics & Equilibrium quiz draws on every topic in this area.
Where Rate vs Time Graphs fits in Kinetics & Equilibrium
Rate vs Time Graphs is topic 79 of 91 in Kinetics & Equilibrium.