Calculating Equilibrium Concentrations
Ethan Taylor
7 min read
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Study Guide Overview
This study guide covers ICE (RICE) tables for equilibrium calculations. It explains how to set up and use ICE tables to find equilibrium concentrations, including the use of the 5% approximation to simplify calculations. The guide also connects these concepts to acid-base chemistry and provides practice problems and exam tips.
#Equilibrium Calculations: Mastering ICE Tables
Hey there, future AP Chem master! 🧪 Let's break down ICE tables – your secret weapon for equilibrium problems. It might seem like a lot, but by the end of this review, you’ll be solving these like a pro.
#What are ICE Tables?
At equilibrium, the forward and reverse reaction rates are equal, and concentrations remain constant. But what if we need to find those equilibrium concentrations? That’s where ICE tables come in!
ICE Tables (or RICE tables) help organize initial concentrations, changes, and equilibrium concentrations. They are essential for solving equilibrium problems when you are given the equilibrium constant (K) and initial concentrations.
- Initial: Concentrations at the start of the reaction.
- Change: Change in concentration as the reaction reaches equilibrium (use 'x' to represent unknown changes).
- Equilibrium: Final concentrations at equilibrium.
- Reaction: (Optional) The balanced chemical reaction.
#Setting Up an ICE Table
Let's use the reaction: CH₃COOH ⇌ CH₃COO⁻ + H⁺ (K = 1.8 * 10⁻⁵)
Remember, reactants lose concentration (-x), while products gain concentration (+x) as the reaction proceeds.
| Reaction | CH₃COOH | CH₃COO⁻ | H⁺ |
|---|---|---|---|
| Initial | 1 M | 0 | 0 |
| Change | -x | +x | +x |
| Equilibrium | 1 - x | x | x |
#Solving for Equilibrium Concentrations
-
Write the equilibrium expression:
K = [CH₃COO⁻][H⁺] / [CH₃COOH]
-
Plug in equilibrium concentrations from your ICE table:
1.8 * 10⁻⁵ = (x)(x) / (1 - x) = x² / (...
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