Post-Lab Question #1: In introductory chemistry, you were taught about charges,
ID: 934976 • Letter: P
Question
Post-Lab Question #1: In introductory chemistry, you were taught about charges, as in the ionic charges in a compound like MgCl2. In many cases, charges and oxidation numbers are similar, if not the same. That said, for organic molecules, charges and oxidation numbers are usually very different. Explain why atom/ion charges and oxidation number are essentially the same for MgCl2 while they are very different for something like methane, and the assumptions that are made when discussing each. Be sure to support your claims. (5 points) Post-Lab Question #2: In this experiment, you check to see if the reaction is complete by testing a bit of the reaction mixture with starch iodine. The initial reaction that occurs is: a) In this reaction, what is oxidized and what is reduced? Support your choices. (4 points) b) Where does the ''H'' come from? (1 point) c) What happens to the 12 and where does the blue-black color come from? Even though 12 is purple, this is not where the blue-black color comes from.Explanation / Answer
In an inorganic compound like MgCl2 , the more electronegative element will acquire a negative charge and more electropositive will acquire positive charge and that charge will be oxidation state of that element
here Mg: +2
and Cl : -1
However in case of organic comounds the charge distribution is affected by the facts that
1. The carbon attached to another carbon will have zero charge
2. Carbon is generally bonded to more electropositive hydrogen
in case of CH4:
charge on each hydrogen = +1
so charge on carbon = -4
so oxidation state of carbon is = -4
2. in case of CH3F
the charge on each hydrogen is = +1
charge on F is -1
so charge on carbon = +2
3. CCl4:
charge on cl is =-1
charge on carbon will be = +4
so the oxidation state may vary form +4 to -4.
Quesiton 2
The species which have decrease positive oxidation state is said to be reduced and vice versa oxidized
here
The oxidation state of Cl in ClO- is +1 so it reduced to Cl- ( -1)
oxidation state of I- is -1 and it oxidized to I2 (0)
The medium is acidic so the H+ comes from there only ( to balance the equation)
I2 is being get adsorbed by the indicator ( starch)
The colour of iodine starch adsorbed complex is blue.