titrations

By: Felipe De la Garza

Titrations

Uses of titration:• Food processing

• Acid number

• Acid-base

• Education

• Bio-fuel

• Urine exams

• Diagnosis for diabetes

Av x Ac = Bv x Bc

Volume in the Erlenmeyer x Concentration (molarity) in Erlenmeyer = Volume used up in Burette x concentration of substance in Burette

Av x Ac = Bv x Bc

(Acid volume x acid concentration = base volume x base concentration)

V1 x C1 = V2 x C2

Background knowledge

An acid-base titration is a neutralization reaction that is performed in the lab in order to determine an unknown concentration of acid or base. The moles of acid will equal the moles of base at the equivalence point. Here's how to perform the calculation to find your unknown.

For example, if you are titrating hydrochloric acid with sodium hydroxide:

HCl + NaOH → NaCl + H2O

You can see from the equation there is a 1:1 molar ratio between HCl and NaOH. If you know that titrating 50.00 ml of an HCl solution requires 25.00 ml of 1.00 M NaOH, you can calculate the concentration of hydrochloric acid, [HCl]. Based on the molar ratio between HCl and NaOH you know that at the equivalence point:

moles HCl = moles NaOH

MHCl x volumeHCl = MNaOH x volumeNaOH

MHCl = MNaOH x volumeNaOH / volumeHCl

MHCl = 25.00 ml x 1.00 M / 50.00 ml

MHCl = 0.50 M HCl

Materials• Burette

• Erlenmeyer Flask

• HCl

• NaOH

• PTH (phenolphthalein)

• Stand

• Burette Clamps

• Funnel

Procedure:• Clip the burette to the

burette stand, using the burette clamps

• Fill the burette till the zero (0) mark, with HCl

• Fill the Erlenmeyer Flask with 250ml of NaOH, and add ten (10) drops of PTH

• Slowly, let the HCl from the burette pour down into the Erlenmeyer with the NaOH

• Stir constantly

• Drop by drop, wait until the reaction turns transparent. 1 drop will change the reaction.

• Stop the flow of the burette

VIDEO

ResultsVargas, Villary, Alvarez, Zheng, Fiedler 24.1 and 24.8

Ignacio, Mariana F, Carolina, Mariana Cortés 24.3

María Cristina Lara, Kopper, Cristina Mariana Corella 24.3

Fumero, Priscila, Felipe García, Fourger, Paula Madrigal 23.9 and 23.3

Sofía Soley, Valentina, Miranda, Adrián, de la Garza, Natalia Barrantes 23.2

Average: 23.98

SD: 0.5831

Standard Deviation

How far where the results from the actual answer? Standard deviation shows how much variation exists from the average to the expected value.

68% of the data collected fall one (1) SD from the mean

95% of the data collected fall two (2) SD from the mean

Av x Ac = Bv x Bc

23.98ml x 1.0m/L = 250ml x m/Lb

23.98/250 = Mb

0.09592 = Mb

Ratio:

HCl : NaOH

10.4253 : 1

Conclution:The HCl is 10.4253 times stronger than

NaOH