RP1 - Making up a standard solution and carrying out an 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?
- weigh the sample bottle containing solid
- transfer sample into beaker and reweigh
- record mass difference
- add distilled water and stir with glass rod until all dissolved
- transfer to volumetric flask with washings
- make up to 250cm3 mark by adding distilled water
- shake flask
What is the weighing by difference technique?
It is a method to weigh materials
accurately.
Mass of substance = Mass of weighing
dish and substance - Mass of dish after substance has been transferred.
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 the 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 0.1 cm3 of each other
What are some common potential
hazards and risks in the laboratory?
Bunsen burner - burns
chemicals -irritant/toxic
glass-may break and cut you
