A bioengineer preparing cells for cloning bathes a small...

A bioengineer preparing cells for cloning bathes a small piece of rat epithelial tissue in a TRIS buffer (see Problem 19.108 ). The buffer is made by dissolving 43.0 $\mathrm{g}$ of TRIS $\left(\mathrm{p} K_{\mathrm{b}}=5.91\right)$ in enough 0.095$M \mathrm{HCl}$ to make 1.00 $\mathrm{L}$ of solution. What is the molarity of TRIS and the pH of the buffer?

A bioengineer preparing cells for cloning bathes a small piece of rat epithelial tissue in a TRIS buffer (see Problem 19.108 ). The buffer is made by dissolving 43.0 $\mathrm{g}$ of TRIS $\left(\mathrm{p} K_{\mathrm{b}}=5.91\right)$ in enough 0.095$M \mathrm{HCl}$ to make 1.00 $\mathrm{L}$ of solution.
What is the molarity of TRIS and the pH of the buffer?

Key Concepts

Buffer Solutions

A buffer solution consists of two components—a weak acid and its conjugate base or a weak base and its conjugate acid—that resist changes in pH when small amounts of acid or base are added. This ability to moderate pH variations is crucial in many biological and chemical systems, where maintaining a nearly constant pH is important for proper function or reaction progression.

Acid?Base Equilibrium

Acid–base equilibrium is the state where the concentrations of acids, bases, and their conjugate pairs remain constant over time. This equilibrium underlies the behavior of buffers, as the weak acid and its conjugate base interconvert in response to pH changes, governed by equilibrium constants such as Ka or Kb.

Conjugate Acid?Base Pairs

In acid–base chemistry, a conjugate acid–base pair consists of a species and the form it takes after donating or accepting a proton. Understanding the relationship between a weak base and its conjugate acid is vital for predicting the behavior and pH of buffer solutions, as their relative amounts determine the buffer’s effectiveness.

Molarity and Stoichiometry

Molarity is a measure of concentration, defined as moles of solute per liter of solution, and is essential for quantitative analysis in chemistry. Stoichiometry involves using the quantitative relationships in a chemical reaction, such as the reaction between a weak base and a strong acid, to determine the amounts of substances present after the reaction.

Henderson?Hasselbalch Equation

The Henderson–Hasselbalch equation provides a relationship between the pH of a buffer solution and the concentration ratio of the conjugate base to the weak acid. It is an essential tool for calculating pH in systems that involve buffers, by incorporating the relevant acid dissociation constant (pKa) or its counterpart series with a weak base and its conjugate acid.

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