RPA Titration Flashcards
What is a standard solution?
A solution of a known concentration
How do you make a diluted solution of HCl
Add 25cm3 of HCl into the volumetric flask using a pipette
Make the solution up to the line by adding distilled water
What equipment is used to carry out a titration
Pipette and pipette filler - accurately measure out the volume of a reactant before transferring it to a conical flask
Burette- controlled way to add small volumes of one reactant to the other reactant
How do you carry out a titration
Once the pipette has been used to place HCl into a conical flask, fill the burette with NaOH. Record initial volume
Add a few drops of phenolphthalein indicator into a conical flask
Open the burette tap and allow the NaOH to flow into a conical flask, swirling it into the contents
Close the burette tap when the expected colour change takes place. Use a white tile so the colour change is easier to identify
Record final burette volume
Repeat until you get concordant results, then calculate a mean titre
Why are acid based indicators used
To detect when a reaction reaches completion, usually by the presence of a colour change
What are concordant results
Results within 0.1cm3 of each other
How would you analyse the results from this titration
Calculate mean titre using concordant results
Calculate the number of moles of NaOH in the mean titre (n= cv)
Calculate the number of moles of HCl that were present in the 250cm3 diluted solution
Use this to calculate the concentration of the original solution of HCl
What are some potential risks and hazards in the lab
Chemicals –> irritant/corrosive/ toxic/ flammable –> wear gloves, eye protection, keep away from the edge, don’t ingest
Glassware –> may smash and cut you –> handle with care, keep away from the edge
