First-Order Reaction
Definition
A first-order reaction is one whose rate depends on the concentration of one reactant raised to the first power.
Analogy
Think about eating M&Ms from a bowl. At first, when there are many M&Ms, you can grab them quickly (high concentration = high rate). But as they start to run out, it takes longer to find and eat each one (low concentration = low rate). This is similar to how first-order reactions work - their speed depends on how much reactant is available.
Related terms
Exponential Decay: The decrease in number or intensity at an exponential rate. It's like how fewer and fewer M&Ms remain as you continue eating them.
Arrhenius Equation: An equation that gives the dependence of reaction rates on temperature. It's like knowing how fast you can eat those M&Ms depending on whether they're melted (warm) or hard (cold).
Pseudo First Order Reaction: A type of reaction where one reactant is present in such large excess that its concentration does not change significantly during the course of reaction and it behaves as if it were a first order reaction. Like having so many bowls full of M&Ms around you that even though you’re eating them, it doesn’t seem like their quantity decreases!
"First-Order Reaction" appears in:
Study guides (3)
Practice Questions (1)
- The decomposition of a pestecide compound applied to crops results in a first-order reaction with 56 days as its half-life. What is the rate constant?
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