posted by Confused on .
I'm doing an Equivalent Weight and Normality experiment and I got very confused on the discussion questions.[ the unknown is titrated with the KMnO4]
1) In this experiment MnO4- is reduced to Mn2+ by the unknown. What is the equivalent weight of MnO4- for this experiment.
Given: Molarity of KMnO4 : 0.079812M
amount of unknown: 1mL
Change in volume of titration: 26.01mL
The equivalent weight is the molar mass (molecular weight) divided by the change in the number of electrons in the titration. The molar mass of KMnO4 is approximately 158 (You need to check it out to get an exact number) and the change in the number of electrons is 5. Mn in MnO4^- is +7 and in Mn^+2 it is +2. From 7 to 2 is 5. One thing confusing about equivalent weights is that a substance can have more than one; for example, KMnO4 can have an equivalent weight = 158/5 in this reaction but if it was carried out in a neutral or basic solution, KMnO4 goes to MnO2 which is a change from +7 to +4 and the equivalent weight is 158/3.
If 2 moles of electrons are required to oxidize 1 mole of unknown, what is the molarity of the unknown solution??
is the molarity reduce to half??