Volumetric analysis Flashcards
What is meant by a standard solution / standardised solution?
a standard solution is a solution whos concentration is accurately known
what is a titration
reacting the solution with another solution whos conc is accurately known
what is a primary standard
a substance which is pure, stabe with air, has a high ,molar mass and can dissolve easily in water to make up a solution os accurately known conc
name examples of a primary standard
anhydrous sodium carbonate
hydrated ammonium iron (II) sulfate
why is deionised water used instead of regular water
tap water contains many different types of ions, these ions unterfere in the titration reaction and could effect the end point
Why is a base not placed in the burette during an reaction
base reacts with glass in burette causing tap to stick and sieze up
Q: Why is the pipette and burette rinsed with deionised water followed by the solution they are
going to contain before they are ready to use
They are rinsed with deionised water to clean them
* Rinsing with solution they are going to contain removes any drops of de-ionised water that
was in the pipette that would dilute the solution
When filling pipettes and burettes with solution, the solution is filled above the mark before
being drained out so the bottom of the meniscus rests on the mark. What is the reason for this?
- This ensures there are no air bubbles in the pipette or burette
and they are entirely filled with solution
Why is it important to remove the funnel from the burette before starting the titration?
Any drops of solution remaining in the funnel could fall back into the burette and change the volume of solution being measured
What procedures are carried out before the titration begins?
Using a dropper, an indicator is typically added to the solution in the conical flask to give the solution a particular colour
A white tile is placed under the conical flask to more easily detect the colour change that will occur at the end point of the titration
What is a titration?
A titration is a method of determining the accurate concentration of a solution of unknown concentration
Why is an indicator typically added to the solution in the conical flask before a titration?
when the teo solutions have completely reacted, a colour change will be observed, the end point of the titration can be known
why is a white tile placed
to more easily identify the colour change that will occour at the end pount of the titration, end point more easily detected
What procedures are followed during a titration to obtain an accurate end point and titre value?
Continuously swirl the conical flask to ensure the two solutions are completely reacting
Use a wash bottle of deionised water to wash down the sides of the conical flask to ensure no drops of the solution coming from the burette are stuck to the sides of the conical flask and all solution released from the burette reacts with the solution in the conical flask
Why is it acceptable at this stage to add deionised water to the conical flask despite taking precautions when filling the pipette and burette to exclude deionised water
The number of moles of solution required is already present in the conical flask and burette and deionised water will not change this
