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This question is about delaying/postponing chemical reactions in general, but I will explain my point based on an example. Most of you will know the famous vinegar and baking soda experiment which allows you to make a volcano or a rocket. What I have noticed when doing this experiment (in particular the rocket experiment) is that if you just put soda in powder form in the bottle and pour in vinegar, a lot of the formed gas escapes before you can put the cork on thus resulting in a less spectacular launch.

In the video I linked above they wrap the soda in paper to allow some time between the addition of vinegar and the start of the reaction. This is a nice trick, but in many cases you don't want any paper inside your 'reaction' vessel. My question is: what are my options to chemically postpone the start of the reaction?

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  • $\begingroup$ Does the use of vinegar make it organic? $\endgroup$ – f p Jun 14 '13 at 13:36
  • $\begingroup$ I'm not sure, I had a hard time picking the tags on this question and I could imagine that people working in organic chemistry/synthesis might be more knowledgeable about the topic. Please feel free to retag if you have suggestions! $\endgroup$ – Michiel Jun 15 '13 at 6:27
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In general the answer to your question is no, you cannot postpone the reaction once the reactants are actually in contact.

Reaction rate usually decreases with temperature. Thus it is possible, but not certain, that if you freeze a reaction mixture down to liquid helium temperatures the reaction would stop. This isn't really practical in general.

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From what I remember, the powder was kept separate.

  • The powder was put on a piece of tissue paper.
  • Put the vinegar in the body of the rocket.
  • Put the cork in with the paper wrapped powder.
  • On putting it in place the vinegar gets to the paper/powder.

This brings me back...

You could work on the cork to put the powder in it without paper or something.

Also, you could make a paste and put it in a hole on the cork.

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  • $\begingroup$ The paste sounds like a very nice technique. Problem is that these methods are still based on physical separation of the vinegar and the soda. What I am looking for is a chemical way to postpone/delay the reaction (not even specifically this reaction, but I thought this was a nice example case) $\endgroup$ – Michiel Jun 15 '13 at 6:30
  • $\begingroup$ The closest I get is catalysis. For reactions that need a catalyst you can do it. For the rest tough luck. $\endgroup$ – f p Jun 18 '13 at 12:23
  • $\begingroup$ You can delay a reaction- chemical poisons do that. They act in various ways but one way is to react with reactive intermediaries (the initial chemicals need to break some bonds to form the intermediaries) and produce inert products which cannot further react. It may even kill a reaction in process. I don't whether there is one for that chemical reaction. $\endgroup$ – user2617804 Dec 26 '13 at 6:10

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