Chem lab chapter 8 acidity constant

Ka =

Concentration of products over solution

The Henderson hasselbalch equation is used to calculate the

Ka of weak acids

Log(x•y) =

Log(x)+log(y)

-log(Ka)=

pKa

Steps to using the Henderson hasselbalch equation

1. Log both sides

2. Separate into log x + log y for concentrations

3. Multiply all terms by negative one

Example of the hassellabch equation

pKa= pH-log y

-log [H+] =

pH

When a base neutralizes half a weak acids the concentration of [HA]=

The concentration of [A-]

[A-]/[HA]=1

Log ([A-]/[HA])=0

At the equivalent point is the pH at which

The base completely neutralizes the acids and the moles of acid initially present, equal the moles of base added

Titration curves

Continuous plots of the changing pH against the volume of the titrant (the base)

Whey is the phenolpthalein ( color changing agent) unnecessary

The equivalent point is easily seen in the graph and it can be monitored via pH

The half neutralization pint

The pH where half the volume of base required to complete the neutralization has been added [HA]=[A-] and pH=pKa

The pH titration curve gives a first visual representation of the

pKa of the weak acids