96689
Titration
- 1) Add a known volume of alkali into a conical flask using a pipette
- 2) Add a few drops of indicator ( Phenolphthalein / Methyl orange)
- 3) Pour some acid into a burette, and record the reading (meniscus)
- 4) Open the tap ,add a small amount of acid and swirl the conical flask to mix
- 5) add acid until the solution is neutral as shown by the colour chnage in the indicator
- 6) Repeat (3 times)
- 6) Repeat (3 times)
- 5) add acid until the solution is neutral as shown by the colour chnage in the indicator
- 4) Open the tap ,add a small amount of acid and swirl the conical flask to mix
- 3) Pour some acid into a burette, and record the reading (meniscus)
- 2) Add a few drops of indicator ( Phenolphthalein / Methyl orange)
- may be used to determin the volumes of acid
and alkali needed to mwke a neutral salt solution
OR to determine the conentration of an acid or
alkali , if the concentration of the other react is
known
- IMPORTANT TO BE CARRIED OUT ACCURATELY
- MENISCUS -- curve in the surface of a liquid
- The burette and pipette used in
accurte titrations must be read from
the bottom of the
meniscus.......precision of burette
reading is +/- 0.05 cm3
- The burette and pipette used in
accurte titrations must be read from
the bottom of the
meniscus.......precision of burette
reading is +/- 0.05 cm3
- Calculations
- concentration in g/dm3 = mass in g / volume in dm3
- concentration in g/dm3 = amount in moles / volume in dm3
- eg 40g in 500 cm3 what is the concentraion in moles /dm3
- 500/1000 = 0.5........40 / 0.5 = 80 so it is 2moles/dm3
- 500/1000 = 0.5........40 / 0.5 = 80 so it is 2moles/dm3
- eg 40g in 500 cm3 what is the concentraion in moles /dm3
- to convert volume from cm to dm divide by 1000 and vice versa
- concentration of a solution can be measured in moles per dm3
- acid = alkali (concentration x volume)
- eg ... a titration is done where 25.0 cm3 of acid is placed into a conical
flask. the concentration of the acid is not known. The acid was
neutralised with 13.5 cm3 of sodium hydroxide of concentraion of
0.10moles/dm3. calculate the concentraion in moles/dm3 of acid.
assume that 1 mole of sodium hydroxide reacts completely with 1 mole
of acid
- ?x25 = 0.1 x 13.5 --- 1.35
- 1.35 / 25 = 0.054 mol/dm3
- 1.35 / 25 = 0.054 mol/dm3
- ?x25 = 0.1 x 13.5 --- 1.35
- eg ... a titration is done where 25.0 cm3 of acid is placed into a conical
flask. the concentration of the acid is not known. The acid was
neutralised with 13.5 cm3 of sodium hydroxide of concentraion of
0.10moles/dm3. calculate the concentraion in moles/dm3 of acid.
assume that 1 mole of sodium hydroxide reacts completely with 1 mole
of acid
- concentration in g/dm3 = mass in g / volume in dm3
- acid usually put in burette.... alkali usually in conical flask.... standard volume is 25cm3
- Phenolphthalein is pink when alkali and colourless when acidic
- Phenolphthalein is pink when alkali and colourless when acidic
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