Titrations 2 Flashcards
Not primary standard
Kmno4
Decomposes in sunlight
Kmno4 in burette
Stains burette
TOP OF MENISCUS IS READ
Why dilute kno4 used
Low solubility
Intense colour
Autocatalysis
Mn2+ acts as the catalyst, its a product of reaction
Why take iron tablets
If iron deficiency, anaemia
Iron is needed to form haemoglobin
Haemoglobin is responsible for transport of oxygen in blood
Sulphuric acid added to beaker after clock glass
Prevent ammonium iron sulphate with oxidising with o2 dissolved in air / water
Sulphuric acid added ti conical flask of kmno4
Insure full reduction of mn+7 to mn+2
Precaution
Wash out all glassware as kmno4 stains
Grind up tablets
Dissolve paste
Usual manner
Use Pestle and mortar to grind
Add sulphuric acid (makes process easier)
Dissolve in beaker if h2so4 , oxodising reason
Cloudy appearance due to coating N.B for calculations
Reason for coating on tablet
To allow slower release of iron into the stomach
Oxidising agent
Mn
Reducing agent
Fe
Purple to brown colour change
Insufficient h2so4 present
Oxidised ?
Endpoint colour change
Purple to pink
Indicator
None required
Kmno4 is self indicating
