Required Practical 1: Make up a volumetric solution and carry out a simple acid - base titration Flashcards
What is a standard solution?
A standard solution is a solution of known concentration
How do you make a standard solution?
1) Measure, using a balance, the mass of solid required
2) Transfer this to a volumetric flask and rinse the remaining weighing bottle content (with distilled water) into the flask so no solid is lost
3)Add a volume of distilled water to dissolve the solid. Swirl the mix
4) Then add more distilled water up to the line on the volumetric flask, Invert multiple times to mix
What equipment is used to carry out a titration?
A pipette and pipette filler are used to accurately measure out the volume of a reactant before transferring it to a conical flask
A burette is used to add small volumes of one reactant to the other reactant (until the reaction has reached completion)
How do you carry out a titration?
1) Once the pipette has been used to place one reactant into the conical flask, fill the burette with other reactant. Record initial volume
2) Add a few drops of indicator to the conical flask
3) Open the burette tap and allow the reactant to flow into the conical flask, swirling it to mix the contents
4) Close the burette tap once the expected colour change occurs, Use a white tile so the colour change is easy to identify
5) Record final burette volume
6) Repeat until you get concordant results, then calculate a mean titre
Why are acid - base indicators used?
To detect when a reaction reaches completion, usually by the presence of a colour change
What are concordant results?
Titres that are within 0.1cm cubed of each other
The student uses a funnel to fill the burette with sulfuric acid before starting the titration. After filling, the student forgets to remove the funnel from the top of the burette
Suggest why this might affect the titre volume recorded
Solution may drip from the funnel so volume measured in the burette would end up being lower
State one advantage of using a conical flask rather than a beaker for the titration
Less chance of drops spilling out while stirring
