stuff

Question 1

how do you get a ph curve

Answer 1

Transfer 25cm3 of acid to a conical flask with a volumetric pipette
calibrate ph meter
Measure initial pH of the acid with a pH meter
Add alkali in small amounts (2cm3) noting the volume added
Stir mixture to equalise the pH
Measure and record the pH to 1 d.p.
Repeat steps 3-5 but when approaching endpoint add in smaller volumes of alkali
Add until alkali in excess

Question 2

How do you use colourimetry to measure complex concentration?

Answer 2

prepare solution with molar ratio of ligands and metal ions corresponding to complex

• maximum concentration of complexes
• measure absorbance
• repeat for smaller moles of ligands
• plot calibration curve
• add excess ligand/metal ion to sample
• measure absorbance of sample and compare to calibration curve