ACID BASE TITRATION

HENNI FITRIANI

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Acid & Base

Acids:

acids are sour tasting

Arrhenius acid: Any substance that, when dissolved in water, increases the concentration of hydronium ion (H3O

+)

Bronsted-Lowry acid: A proton donor

Lewis acid: An electron acceptor

Bases:

bases are bitter tasting and slippery

Arrhenius base: Any substance that, when dissolved in water, increases the concentration of hydroxide ion (OH-)

Bronsted-Lowery base: A proton acceptor

Lewis acid: An electron donor

Introduce Of Acid

Introduce Of Base

Example

STRONG vs WEAK_ completely ionized _ partially ionized_ strong electrolyte _ weak electrolyte_ ionic/very polar bonds _ some covalent bonds

Strong Acids: Strong Bases:HClO4 LiOHH2SO4 NaOHHI KOHHBr Ca(OH)2HCl Sr(OH)2HNO3 Ba(OH)2

Titration

Titration of a strong acid with a strong baseENDPOINT = POINT OF NEUTRALIZATION = EQUIVALENCE POINTAt the end point for the titration of a strong acid with a strong base, the moles of acid (H+) equals the moles of base (OH-) to produce the neutral species water (H2O). If the mole ratio in the balanced chemical equation is 1:1 then the following

equation can be used.MOLES OF ACID = MOLES OF BASEnacid = nbase

Since M=n/VMAVA = MBVB

Finding the equivalence point of a titration

Use a pH meter

- Plot pH versus titrant volume

- Center vertical region = equivalence point

Use an Acid-Base Indicator

- Acid-Base Indicator = molecule that changes color based on pH

- Choose an indicator that changes color at the equivalence point

- End Point = when the indicator changes color. If you have chosen the wrong indicator, the end point will be different than the eq. pt.

- Indicators are often Weak Acids that lose a proton (causing the color change) when [OH-] reaches a certain concentration

HIn + OH- In- + H2O

Acid-Base Indicators

Technique Of

Titration

TITRATION

MAVA = MBVB

Example:1.Suppose 75.00 mL of hydrochloric acid was required to

neutralize 22.50 mLof 0.52 M NaOH. What is the molarity of the acid?HCl + NaOH H2O + NaClMa Va = Mb Vb rearranges to Ma = Mb Vb / Va

so Ma = (0.52 M) (22.50 mL) / (75.00 mL) = 0.16 M

Now you try:2. If 37.12 mL of 0.843 M HNO3 neutralized 40.50 mL of

KOH, what is the molarity of the base?Mb = 0.773 mol/L