titrations
DESCRIPTION
TRANSCRIPT
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