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MCAT GC WORKING > Oxidation State Extras > Flashcards

Oxidation State Extras Flashcards

1
Q

What is the oxidation number for oxygen in O2?

A

0

The oxidation number for every element in its standard state is zero.

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2
Q

What is the oxidation number for oxygen in H2O?

A

-2

This is oxygen’s oxidation number in most compounds.

For the purposes of calculating oxidation number, the oxygen can be assumed to have completely removed the electron from each hydrogen atom, leaving it with an oxidation number of -2.

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3
Q

What is the oxidation number for oxygen in H2O2?

A

-1

Peroxides are the only compounds where oxygen has an oxidation number of -1, this is due to each Hydrogen being only able to donate 1 electron each.

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4
Q

What is the oxidation number for nitrogen in NO?

A

+2

Oxygen’s oxidation state is -2, and the molecule is neutrally charged, so the nitrogen must be +2.

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5
Q

What is the oxidation number for nitrogen in NO2?

A

+4

The oxidation state of each oxygen is -2, and the molecule is neutrally charged, so the nitrogen must be +4.

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6
Q

What is the oxidation number for nitrogen in NO3-?

A

+5

The oxidation state of each oxygen is -2 (-6 total), and the ion has an overall charge of -1, so the nitrogen must be +5.

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7
Q

What is the oxidation state of

Nitrogen in

  1. HNO3
  2. NO
A
  1. +5
    H=+1, O3=3(-2)=-6, N must be +5 to compensate.
  2. +2
    O=-2, N must be +2 to compensate.
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8
Q

What is the oxidation state of

Sulfur in

  1. H2S
  2. S8
A
  1. -2
    H2=2(+1)=2, S must be -2 to compensate.
  2. 0
    This is Sulfur’s standard state, all atoms are zero oxidation in their standard state.
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9
Q

What is the oxidation state of

Iron in

  1. FeO3
  2. FeH
A
  1. +6
    O3=3(-2)=-6, Fe must be +6 to compensate.
  2. -1
    H=+1, Fe must be -1 to compensate.
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10
Q

What is the oxidation state of

Carbon in

  1. CO
  2. CO2
  3. CH4
A
  1. +2
    O=-2, C must be +2 to compensate.
  2. +4
    O2=2(-2)=-4, C must be +4 to compensate.
  3. -4
    H4=4(+1)=+4, C must be -4 to compensate.
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11
Q

What is the oxidation state of

Silicon in

  1. H4Si
  2. SiF
A
  1. -4
    H4=4(+1)=+4, Si must be -4 to compensate.
  2. +1
    F=-1, Si must be +1 to compensate.
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12
Q

What is the oxidation state of

Carbon in

  1. C2H2
  2. C2Cl6
A
  1. -1
    H2=2(+1)=+2, C2 needs to be -2 to compensate, hence C must be -2/2=-1.
  2. +3
    Cl6=6(-1)=-6, C2 must be +6 to compensate, hence C must be 6/2=3.
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13
Q

What is the oxidation state of

Iron in

  1. FeO2
  2. FeCl2
  3. HFeO2
A
  1. +4
    O2=2(-2)=-4, Fe must be +4 to compensate.
  2. +2
    Cl2=2(-1)=-2, Fe must be +2 to compensate.
  3. +3
    H=+1, O2=2(-2)=-4, Fe must be +3 to compensate.
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14
Q

What is the oxidation state of

Nitrogen in

  1. N2
  2. N2O3
A
  1. 0
    This is Nitrogen’s standard state, all atoms are zero oxidation in their standard state.
  2. +3
    O3=3(-2)=-6, N2 needs to be +6 to compensate, hence N must be 6/2=3.
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15
Q

What is the oxidation state of

Sulfur in

  1. SO2
  2. H2SO4
A
  1. +4
    O2=2(-2)=-4, S must be +4 to compensate.
  2. +6
    H2=2(+1)=+2, O4=4(-2)=-8, S must be +6 to compensate.
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16
Q

What is the oxidation state of

Silicon in

  1. SiO2
  2. Si2Cl4
  3. NaSi
A
  1. +4
    O2=2(-2)=-4, Si must be +4 to compensate.
  2. +2
    Cl4=4(-1)=-4, Si2 needs to be +4 to compensate, hence Si must be 4/2=2.
  3. -1
    Na=+1, Si must be -1 to compensate.
17
Q
A
18
Q

What is the fastest process to balance an equation?

A
  1. Start by finding the most complex molecule in the reaction, give it as low a coefficient value as possible (usually 1 or 2)
  2. Balance the atoms of the corresponding elements on the opposite side of the equation.
  3. Total the number of remaining atoms of each element that have not yet been balanced, and adjust the remaining molecule numbers to satisfy (don’t go back and adjust already balanced ones)
  4. Leave balancing any single element molecules (O2, N2, H+, etc) until the very end.
19
Q

Please give the balanced equation for:

Sn + HCl → SnCl2 + H2

A

Sn + 2 HCl → SnCl2 + H2

20
Q

What is the oxidation state of

Silicon in

  1. SiO2
  2. Si2Cl4
  3. NaSi
A
  1. +4
    O2=2(-2)=-4, Si must be +4 to compensate.
  2. +2
    Cl4=4(-1)=-4, Si2 needs to be +4 to compensate, hence Si must be 4/2=2.
  3. -1
    Na=+1, Si must be -1 to compensate.
21
Q

What is the oxidation state of

Sulfur in

  1. SO2
  2. H2SO4
A
  1. +4
    O2=2(-2)=-4, S must be +4 to compensate.
  2. +6
    H2=2(+1)=+2, O4=4(-2)=-8, S must be +6 to compensate.
22
Q

What is the oxidation state of

Nitrogen in

  1. N2
  2. N2O3
A
  1. 0
    This is Nitrogen’s standard state, all atoms are zero oxidation in their standard state.
  2. +3
    O3=3(-2)=-6, N2 needs to be +6 to compensate, hence N must be 6/2=3.
23
Q

What is the oxidation state of

Carbon in

  1. C2H2
  2. C2Cl6
A
  1. -1
    H2=2(+1)=+2, C2 needs to be -2 to compensate, hence C must be -2/2=-1.
  2. +3
    Cl6=6(-1)=-6, C2 must be +6 to compensate, hence C must be 6/2=3.
24
Q

What is the oxidation state of

Iron in

  1. FeO3
  2. FeH
A
  1. +6
    O3=3(-2)=-6, Fe must be +6 to compensate.
  2. -1
    H=+1, Fe must be -1 to compensate.
25
Q

What is the oxidation state of

Carbon in

  1. CO
  2. CO2
  3. CH4
A
  1. +2
    O=-2, C must be +2 to compensate.
  2. +4
    O2=2(-2)=-4, C must be +4 to compensate.
  3. -4
    H4=4(+1)=+4, C must be -4 to compensate.
26
Q

What is the oxidation state of

Silicon in

  1. H4Si
  2. SiF
A
  1. -4
    H4=4(+1)=+4, Si must be -4 to compensate.
  2. +1
    F=-1, Si must be +1 to compensate.
27
Q

Question

A

Answer

MCAT GC WORKING (11 decks)

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