Here's what  you need to do.

Google the reaction and find all you can about the products.

Don't forget that the Phenol Red is aqueous, which means it is dissolved in H20.

Write the entire equation out and determine the products of the reaction.

Which of these products is a gas?

Google Phenol Red and research what it is composed of and it purposes.

Remember that Phenol Red is only an indicator and not in the reaction equation.

Specific tests for gases can be found at http://www.gcsescience.com/itestsforgases.htm  , so go there for help.  Or, google the words "gas tests chemistry" and see what you can find.

Complete a one page write up about this lab.  Refer to the lab write-up link above for help.