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3Cl2(g) + 6NaOH(aq) →5NaCl(aq) + NaClO3(aq) + 3H2O(l)

 

CO2(g) + H2O(l) → H2CO3(aq)

 

2 NH4Cl(aq) + Ca(OH)2(aq) →2 NH3(aq) + 2H2O(l) + CaCl2(aq)

 

2HNO3(aq) + 6HI(aq) →2NO(g) +3 I2(s) + 4H2O(l)

Identify which one is a redox reaction and which one is not a redox reaction. 

Which equation is an example of a disproportionation reaction? 

6 years ago

Answered By Leonardo F

Let's review the concept or redox and disproportionation reactions: redox reactions involve one chemical element increasing its oxidation state (oxidizing) and another decreasing its oxidation number (reducing). For a disproportionation reaction, we have one chemical element both increasing and decreasing its oxidation state. Now, let's analyze the reactions one by one:

Reaction 1) In Cl2, the chlorine has an oxidation state of 0. In NaCl, it has an oxidation number of -1. In NaClO3, it's +5, because oxygen is -2 and Na is +1 (remember that the sum of the oxidation states in a molecule, without any charge, is ZERO). Hence, the chlorine is both increasing and decreasing its oxidation states, and this reaction is a DISPROPORTIONATION one.

Reaction 2) The carbon has oxidation state of +4 both in CO2 and H2CO3. The hydrogen has oxidation number of +1 and oxygen is -2. None of the chemical elements are changing their oxidation states, so this is NOT a redox reaction.

Reaction 3) The nitrogen has an oxidation state of -3 both in NH4Cl and NH3, because the chlorine is -1 and the hydrogen is +1. The calcium has an oxidation number of +2 and the oxygen, -2. Hence, none of the chemical elements are changing their oxidation states and this is NOT a redox reaction.

Reaction 4) The nitrogen has an oxidation state of +5 in HNO3, because the hydrogen is +1 and the oxygen is -2. In NO, it changes its oxidation state to +2. Hence, the nitrogen suffered reduction. The iodine has an oxidation number of -1 in HI and 0 in I2, so it's oxidizing. Since one chemical element increases its oxidation state while another decreases it, this IS  a redox reaction.