The end point of an ozonolysis.

Ozone (O3) is among the most powerful oxidizing agents known, far stronger than O2. It is also unstable at high concentrations, decaying to ordinary diatomic oxygen. It has a deep blue color and when it is used in organic chemistry a good indicator that the reaction is ready when the characteristic blue color of the ozone is seen in the reaction mixture.

Ozone is a quite reactive molecule, it attacks almost everything. A great example is the rubber septa at the two side neck of the flask. It was degraded by ozone during the reaction as seen. 

Ozonolysis is used when we need to cleave double bonds in a molecule to get aldehydes or ketones (even carboxylic acids), just as shown here: 

For ozonolysis: the overall scheme looks like this

To help you remember the reaction - cut the alkene in half, and stick an oxygen atom on each sideHowever the full mechanism is as follows:

Breaking and Making of Olefins Simultaneously Using Ozonolysis: Application to the Synthesis of Useful Building Blocks and Macrocyclic Core of Solomonamides

A simple and practical one-pot, two-directional approach to access olefinic esters through simultaneous breaking and making of olefins using ozonolysis of alkenyl aryl selenides is disclosed. The scope of the method with a variety of examples is demonstrated, and the end products obtained here are useful building blocks. As a direct application of the present method, the macrocyclic core of…

Ozonolysis

An alkene, "A", with molecular formula, C6H12 on reductive ozonolysis gives two products. One of these gives a positive iodoform test but negative Tollen’s reagent test. The other product gives a positive Tollen’s reagent test but negative iodoform test. What is the name of "A"?

Answer:

An alkene having 5 carbon atoms that produces an optically active compound as major product on treatment with aqueous HI also forms two different carbonyl compounds on reductive ozonolysis. Both of the carbonyl compounds respond positive to Silver Mirror Test. What is the name of the alkene?

Answer:

As both the carbonyl compounds respond positive to Silver Mirror test, it can be inferred that they are aldehydes. Also, as both the carbonyl groups are different, the molecule is not symmetric. The molecule also produces an optically active compound on treatment with aq. HI. Putting all this together we can conclude that the alkene should be pent-2-ene.