CHEM 113 1st Edition Lecture 25 Outline of Last Lecture- The Lewis acid-base definitiono Lewis Acido Lewis BaseOutline of Current Lecture- Buffer Capacity- Buffer Range- Preparing a BufferCurrent Lecture- Buffer Capacity o The buffer capacity is a measure of the “strength” of the buffer, its ability to maintain the pH following the addition of a strong acid or baseo Capacity depends on component concentrations, both absolute and relative concentrations The greater the concentrations of the buffer components, the greater its capacity to resist pH changes The closer the component concentrations are to each other, the greater the buffer capacity - A buffer has the highest capacity when the component concentrations are equal- Buffer Rangeo The buffer range is the pH range over which the buffer is effectiveo Buffer range is related to the ratio of buffer component concentrations The close [HA]/[A-] is to 1, the more effective the buffer If one component is more than 10 times the other, buffering action is poor. Since log10=1, buffers have a usable range within plus or minus 1 pH unit of the pKa of the acid component.- Preparing a Buffero 1). Choose the conjugate acid-base pair The pKa of the weak acid component should be close to the desired pHo 2). Calculate the ratio buffer component concentrationsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. pH= pKa + log ([base]/[acid])o 3). Determine the buffer concentration and calculate the required volume of stock solution and/or masses of componentso 4). Mix the solution and correct the
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