5.1.2 Titration
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What are the two names of the apparatus used in Titration
• Volumetric Pipette • Burette
what is a volumetric pipette used for
measuring out 25 cm^3 very accurately
What is a Burette used for?
measure any volume to the nearest 0.05cm^3
Which apparatus does the known acid go in
Burette
Which apparatus does the unknown alkali go in
Conical flask
What is the setup of the conical flask
• using a volumetric pipette to measure out 25cm^3 into the conical flask • add a few drops of either methyl orange or phenolphthalein indicator to the flask • Fill burette with known acid and clamp it above the conical flask
why do you use methyl orange or phenolphthalein and not a universal indicator
Because it doesn’t work as it changes the colour too gradual
What is the steps of titration
• Using the pipette measure 25.0cm^3 of unknown acid • transfer into conical flask Place on a white tile • Add drops of methyl orange into conical flask - place on white tile • Fill burette with known acid - record initial volume • Whilst swirling add in drops of Acid until reach end point - red-yellow 5.Record final volume - calculate difference ( final - initial reading) • Repeat experiment until you reach concordant results • within 0.20cm^3 of eachother • calculate an average
What does concordant results mean
Results within 0.20cm^3 with eachother
Why will the start colour be alkaline and the end colour be acid
Because the last drop of acid always has a tiny amount more than is needed to neutralise.
How do you work out titration results in mole calculations
• draw a grid with the information • Look at the balancing numbers and work out a ratio • Use the mole ratio form the equation to work out the moles of the substance • with the calculated moles work out the concentration • use the equation (moles= conc x vol