Redox Titration

Potassium permanganate is a secondary standard and to standardize it, you can use ferrous ammonium sulfate ir Mohrs salt. Prepare a 0.1M Fe2+ solution pipette 10 ml into an erlenmeyer flask add 10 ML of 1M sulfuric acid and titration it against KMnO4 solution approximate concentration should be 0.02M. The end point is the Color change from clear to pale pink.

Titration Video

Solubility Product Lab

Focus is on Initiating and Planning

Write a lab report for determining solubility product for Ca(OH)2 based on the questions suggested.

  • What are the theoretical considerations for explaining solubility of sparingly soluble salts and predicting the precipitations of these salts.
  • How would you determine the solubility product of Ca(OH)2
  • The suggested method was titration, alternate methods are welcome
  • Include every step in detail, meaning a proper practical procedure.
  • The analysis part needs to be done only when the lab is performed in class.
  • However speculation on possible sources would be good.
  • A written submission is required on Monday.

Naming – ous vs ic

While naming ionic compounds using IUPAC involving multivalent metal ions the oxidation state or valency of the element is shown in brackets after the name of the metal using roman numerals. Example Iron (II) Sulfate = Fe2SO4, if you name the same compound using trivial naming system or the older naming system the compound is called Ferrous Sulfate.
Multivalent ions when named using the trivial system the metal with lower oxidation system always ends in -ous and the next higher oxidation number will end in -ic.
So Iron (III) Sulfate or Fe2(SO4)3 will be called Ferric Sulfate.
Cu+ = Cuprous ion
Cu2+ = Cupric ionĀ  and so on

 

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Ionic compounds and shapes

Ionic compounds do not have shape, on the other hand molecular compounds have a definite shape. Ionic compounds have a crystal structure, the inter ionic attraction being electrostatic the force of attraction is directed in space in a three dimensional area, in NaCl each sodium ion is surrounded by six chloride ions and each chloride ion is surrounded by six sodium ions effectively the positive charge is satiated by the negative charges surroundings it. If you look closely you would see that if the positive charge is placed at a point where the three axis intersect the chloride ions would be on either ends of the X, Y and Z axis. This potentially would lead to an FCC type of unit cell, and in each unit cell we would have 4 formula units of NaCl.

The formula of sodium chloride is represented as the simplest ratio in which the positive and negative ions combine to form a neutral molecule. Hence MgO and not Mg2O2. Every ionic compound would belong to one of the 7 crystal systems.
FCC represents face centered cubic unit cell. There are 4 formula units in one unit cell of NaCl, yet the formula is represented as a 1:1 ratio of positive to negative compound.

 

 

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