What are the oxidizing and reducing agents in this redox reaction?

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Discussion Overview

The discussion centers on identifying the oxidizing and reducing agents in the redox reaction between sulfuric acid (H2SO4) and hydroiodic acid (HI). Participants explore the assignment of oxidation numbers and the implications for determining the agents involved in the reaction.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that H2SO4 is the reducing agent and HI is the oxidizing agent based on their assigned oxidation numbers.
  • Another participant agrees that SO4 oxidizes HI to I2 but questions the identification of the reducing agent and the correctness of the oxidation numbers.
  • A third participant asserts that sulfur is gaining electrons and is being oxidized, thus confirming H2SO4 as the reducing agent and HI as the oxidizing agent, while also questioning the oxidation number assigned to iodine.
  • Further clarification is provided regarding the definitions of oxidation and reduction, with references to the mnemonic OIL RIG (Oxidation Is Loss, Reduction Is Gain), while also noting the complexity of assigning oxidation numbers to molecules versus atoms.

Areas of Agreement / Disagreement

Participants express differing views on the assignment of oxidation numbers and the identification of the oxidizing and reducing agents. There is no consensus on these points, and the discussion remains unresolved.

Contextual Notes

There are limitations regarding the assumptions made about oxidation numbers, and the discussion highlights the complexity of assigning these numbers in the context of the reaction.

sami23
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H2SO4 (aq) + 2HI (aq) --> SO2 (g) + I2 (s) + 2H2O (l)

Indicate the oxidizing and reducing agents.
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I started by assigning oxidation numbers to all the atoms:
H=+1
O=-2
S=+6 to +4
I=-2 to 0

I think H2SO4 is the reducing agent and 2HI is the oxidizing agent. Is this correct?
 
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SO4 oxidizes HI to I2. But what is the reducing agent and are my oxidation numbers for the atoms correct?
 
Sulfur gained electrons, and is being oxidized. thus, your reducing agent is H2SO4. I Lost electrons, and thus HI is the oxidizing agent.

this is assuming your oxidation numbers are correct which if i am not mistaken your'e "I" is -1? "H 1+" "I -1" "HI 0"
 
Grogerian said:
Sulfur gained electrons, and is being oxidized.

OIL - oxidation is loss

I Lost electrons, and thus HI is the oxidizing agent.

RIG - reduction is gain.

this is assuming your oxidation numbers are correct which if i am not mistaken your'e "I" is -1? "H 1+" "I -1" "HI 0"

You can't assign ON to molecule, only to atoms, thus HI doesn't have ON, just (neutral) charge.

sami23 said:
I=-2 to 0

For that you will need H2+. No such animal.
 

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