[Ter]

Hi can someone help me clear some this confusion?

Recently I read somewhere that by dissolving chloride gas into water, hydrochloric acid and chloric(I) acid are formed. Blue litmus paper turns red due to the formation of the hydrochloric acid and then the red litmus paper will be bleached due to the decomposition of chloric(I) acid into hydrochloric acid and oxygen.

However, I remember those lab experiments in school, I had held the litmus paper over the solution in a test tube and it turned from blue to red to white. It had never touched the solution, so how is it that it can induce the litmus paper to change colour? After all, the hydrochloric acid and chloric acid are aqueous, are found in the solution itself, and since they are the ones that affect the color of the litmus paper, isn't it that the litmus paper will only change colors when dipped into the solution and not held above the solution?

My teacher at that time said simply that chlorine gas bleached the litmus paper. It made sense since chlorine is a gas that can rise up to change the color of the litmus paper. But now, since I realized that it is not the chlorine that changes the color of litmus but the compounds in solution...

Did I recall the experiments wrongly or..?

Thank you so much for reading and kind efforts

[Arkcon]

There are two competing reactions you have to consider:

There is an acid-base reaction with litmus.  Base colors it blue, acid colors it red.  Maybe, you can write something like a reaction for this statement, using a common base and acid, for example, sodium hydroxide and sulfuric acid.

There is a bleaching reaction with, in your case, chloric acid.  This is an oxidation, the large complicated organic compound litmus is destroyed by the bleaching agent.   You can sort of write this one out as well, you can use any oxidizer, like permanganate, or something else.

You (and maybe your teacher) are making the problem little bit more difficult, you use the term bleaching for the pH color change and for the color loss.  You should try to separate all the possibilities, to describe what really happens.

[Ter]

Thank you for your reply!
May I ask how you would describe it then?

[Arkcon]

You saw the color change from blue to red to white occur stepwise, separated in time, while you watched.  Describe the process in that way.

[Ter]

But as for what caused the color change? Is it right that litmus paper was held above the test tube?  How would I explain that it will be bleached when chloric acid is in solution while the litmus paper is not in contact with the solution?

Thank you so much!