It's a combustion.

Combustions are part of what class of chemical reactions?

Combustions are oxydations

This reaction produces heat. It is an ... reaction.

exothermic

What is CO₂ like?

CO₂ is a colorless, odourless, tasteless gas, more dense than air. It is called carbon dioxide.

What is the meaning of the yellow color of bromothymol?

It means that CO₂ reacts with water to form an acid.

What is the formula of that acid? Describe it!

Carbonic acid H₂CO₃. It is a colorless, water-soluble substance.

Write down the equations of the two observed reactions!

C+O₂→ CO₂ CO₂+H₂O→ H₂CO₃