Home > Chemistry > Chemistry 1A Part Deux: Lecture 16 Notes

Chemistry 1A Part Deux: Lecture 16 Notes

Overview

Today is a 50 minute extravaganza on titration.  She also discusses strong and weak acid/base chemistry again.

Details

Acids react with bases to form neutral products.  Neutral is defined as pH = 7.

In casein found in milk, particles consisting of proteins and calcium phosphate nanoclusters.  Ca3(PO4)2 with a pH dependent radius of 100 nm.  There are fat globules there.

She performs a demonstration with a buret, buret clamp, and Erlenmeyer flask.  It is typical to obtain 4 decimal accuracy for good analytic chemists.  The titration determines the amount of acid/base in a solution.  You deliver a known volume with known molarity.

M1V1 = M2V2

When titrating, the  objective is for the concentration of acid to equal the concentration of base:

[HA] = [A-]

A strong acid with a strong base

HCl + NaOH = NaCl + H20

Net Ionic Equation

H+ + OH- = H2O

The titration curve essentially has a sigmoid shape.  At the equivalence point, the number of moles of H+ is the number of moles of OH-.  The end point is when your indicator changes color.

pH at the Equivalence Point

We’d like an indicator that changes color at the equivalence point.  The graph of pH versus volume will be vertical there.

Weak Acid and Strong Base

HA + NaOH = NaA + H2O

HA + OH- = A- + H2o

This reaction does not go to completion, dissociation is not complete.

Stoichiometric Acid Base Reactions

Strategy

1 Assume the reaction goes to completion

2 Look at what’s left and ask if it changes the pH

Strong Acid and Strong Base

H+ + OH- = 2H2O

pH = 7 due to water autoionization

Weak Acid and Strong Base

CH3COOH + OH- = CH3COO- + H2O

pH?>7 due to the reaction of CH3COO- with H2O to produce a small amount of acetic acid and OH-.

Review

G = H-TS

PV = nRT

K = products/reactants

KHAP pK = pH + log (acid/base)

Tissue: epithelial, connective, muscular, nervous

Electronegativity: NOF

s 2, p 6, d 10, f 14

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