Titration Flashcards
What is titration?
A technique by which the concentration of a solution is determined by measuring the volumes of solutions involved in the reaction.
What is step 1 in the procedure?
Selection of primary standard
What is a primary standard?
A substance must be a substance of sufficiently high purity and stability such that a standard solution can be prepared with a known concentration, to a high degree of accuracy.
What are some of the important properties of primary standards?
- Water solubility
- High purity
- Definite chemical comp.
- stability in air
- Known chemical formula
-High molecular weight (preferred)
Can substances like NaOH and H2SO4 be used?
Yes, as secondary standards - they have to be standardised against another primary standard.
Identify the most commonly used primary standard.
Anhydrous sodium carbonate (Na2CO3). This makes a basic solution, suitable for analysing acids.
Why wouldn’t NaOH work as a primary standard?
NaOH is deliquescent - absorbs water from the air - thus not pure solution with a definite concentration.
What is step 2 in titration?
Preparation of the Standard solution
What is the procedure of standard soln prep?
- Dissolve the solid primary standard in beaker
- Transfer into vol. flask
- Fill to the gradation line, stopper flask and invert 20 times.
What is the third step of titration?
Selection of appropriate indicator - methyl orange, BB or Phenol.
What is the pH range for methyl orange?
3.1-4.4
What is the pH range for bromothymol blue?
6.0-7.6
What is the pH range for phenolphthalein?
8.3-10.0
What is step 4 of titration?
Rinsing of glassware
What are the 4 steps of titration?
PSIR
