This is an oxidation-reduction (redox) reaction:
4 C-I - 20 e- → 4 CIV (oxidation)
10 O0 + 20 e- → 10 O-II (reduction)
C2H2 is a reducing agent, O2 is an oxidizing agent.
Reactants:

, Ethyne 


, HC#CH 
; Colorless gas with a faint, ethereal odor. [Note: Commercial grade has a garlic-like odor. Shipped under pressure dissolved in acetone.] 
Products:

, {{plainlist| 
, Dry ice
, [CO2]
, R-744 
; Colorless, odorless gas. [Note: Shipped as a liquefied compressed gas. Solid form is utilized as dry ice.] 