Experiment 2

Quantitative Analysis 2 : Redox Titration

Aim : To determine the formula of sodium thiosulphate crystals by redox titration

Directions : You are given a solution of 0.01 molar potassium iodate pipette 
25 ml into a conical flask and ( using a measuring cylinder )add 10 ml of the 
0.2 molar potassium iodide and 10 ml of the 1 molar sulphuric acid . Swirl to mix . 
Titrate against the thiosulphate solution until a yellow-orange ( straw ) colour is 
obtained . Add four drops of the starch solution and continue titrating until 
the blue colour just disappears .
Repeat for at least two more efforts .

Skilled Assessed 
Manipulation and Measurement

Use of the pipette
Point below surface at liquid		1 mk
Meniscus at the mark			1 mk
Proper draining				1 mk

Use of the burette
Filling and Adjusting Volume		1 mk
Reading burette				2 mks
Removing without funnel			1 mk
Swirling flask				1 mk
Manipulating drops			1 mk

Results
Precision of Readings			2 mks
Accuracy of Readings			1 mk