Redox Reactions

Oxidation Numbers:

-oxidation numbers are the hypothetical charge an atom in a compound would have if the bonds were fully ionic

-NOT the same as formal charge

-more electronegative atoms will take electrons from less electronegative atoms

-elements and diatomic gases have an oxidation number of 0 because there are no more electronegative atoms to give up the electrons to

1. An element in a free form has OS = O. 2. In a compound or ion, the sum of the oxidation states equals the total charge of the compound or ion. 3. Fluorine in compounds has OS = —1; this extends to chlorine and bromine only when not bonded to a lighter halogen, oxygen or nitrogen. 4. Group 1 and group 2 metals in compounds have OS = •1 and +2, respectively. 5. Hydrogen has OS = +1 but adopts -1 when bonded as a hydride to metals or metalloids. 6. Oxygen in compounds has OS = —2 but only when not bonded to oxygen (e.g. in peroxides) or fluorine.

•Gr-oup IA “ + 一 positive

-transition metals have variable oxidation numbers depending on the compound they are in (bc/ of their d suborbitals)

-using the rules above, you can find the oxidation numbers of every atom except the transition metal, then subtract those oxidation numbers from the overall charge of the compound to find the transition metal’s oxidation number

13.1 Oxidation states of the transition elements (HL)

What is the oxidation state of zinc in ZnCOa. (Note: the C03 anion has a charge state of -2) Answer Knowing that C03 has a charge of -2 and knowing that the overall charge of this compound is neutral, we can conclude that zinc has an oxidation state of +2. This gives us zn2+ and C03 2, in which the positive and negative charges from zinc and carbonate will cancel with each other, resulting in an overall neutral charge expected of a compound.

-sometimes oxidation numbers of transition metals are indicated in the name (e.g. Copper(II) oxide (CuO), copper has an oxidation number of 2; Chromium(VI) hydrogen phosphate (Cr(HPO4)3), chromium has an oxidation number of 6)

Coordination Compounds:

How to Calculate the Oxidation State of Transition Metals in Coordination Compounds - YouTube

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How to Calculate the Oxidation State of Transition Metals in Coordination Compounds

Example 2— Dealing with More Stuff... [CrC12(H + 2(-1) + 4(0) = 1

Oxidation Numbers of Carbon in organic molecules:

-each bond to a less electronegative atom (i.e. H) gives an electron to carbon confers a -1 oxidation number

-each bond to a more electronegative atom (e.g. O, N, F) takes away an electron from carbon confers a +1 oxidation number

-remember: double bonds count as two bonds, triple bonds count as three

-each bond to another carbon is a zero change in oxidation number (bc/ no electronegativity difference)

-takeaway: electronegativity directly affects the oxidation number of carbon

CO2: oxidation state of C = +4

Balancing Redox Reactions in Acidic Solutions:

  1. Split up whole reactions into half reactions; then for each half reaction:
    1. Balance all atoms except O and H
    2. Add H2O to balance O
    3. Add H+ to balance H
    4. Finally, Add e to balance charges
  2. Bring together half reactions back together, making sure the number of elections balance out
  3. Cancel stuff on both sides of the arrow

How to Balance Redox Equations in Acidic Solution

Balancing Redox Reactions in Basic Solutions:

Same as above, but AT THE END:

  1. Add OH to each side for each H+
  2. Combine each OH and H+ to make H2O
  3. Cancel H2O’s

How to Balance Redox Equations in Basic Solution

Question 59 During glycolysis, pyruvate is reduced to lactate by nicotinamide adenine dinucleotide (NADH). What is the balanced reaction for this conversion? Jack Westin Advanced Solution: On test day, unless you're doing well with time and can afford to systematically go through all of the steps for balancing redox reactions, it's unlikely that the first step you'll take for a question like this will be to write out and resolve each of the half reactions. That said, we'll rovide the math at the end of the ex lanation for this • Let's say you're short on time or just where you want to be, how can you solve this question quickly and accurately? First, check to make sure the NADH to NAD+ ratios are balanced. Next, make sure the net charges on each side of the equation are balanced and neutral. Lastly, if you still don't have the answer, make sure that each side has the same number of each atom so if there are 5 carbons on he left, there are 5 carbons on the ri ht .

Redox Titrations:

Redox titrations | Chemical reactions | AP Chemistry | Khan Academy

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Coordination Complexes:

Transition Metal Complexes

Coordination Compounds Almost all metal ions are found as complex ions (a.k.a. coordination complexes) Meta

Coordination Complex Nomenclature

Metal Complex Nomenclature Ions: ( Iprefixl Iligandl (metall (Charge)

Iodine-Starch test

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iodine–starch test is a chemical reaction that is used to test for the presence of starch. I3 ions are complexed to the starch helix. It can be used to test the reaction rate of amylase. amylase digestion demonstration