How Do You Test for Carbon Dioxide?

Test for carbon dioxide by burning a splint, using litmus or indicator papers or running the gas through lime water. Additionally, according to the National Institutes of Health, a blood test can be performed to determine the amount of carbon dioxide in a person’s blood.

A chemistry lab offers several different ways in which a person can test a gas to determine if it is carbon dioxide, or CO2:

  • Light a splint

  • Collect carbon dioxide gas in a tube by downward delivery or using a gas syringe. Light a splint, which is a long, thin strip of wood. Insert the lit splint into the tube with the gas. If carbon dioxide is in the tube, the flame will go out.

  • Use litmus paper
  • Place a piece of moist litmus paper into the tube with the carbon dioxide gas. If the gas is present, the litmus paper will turn from blue to red.

  • Use universal indicator paper
  • Place a piece of moist universal indicator paper into the gas tube. If carbon dioxide gas is present, the universal indicator paper will turn yellow.

  • Run the gas through lime water
  • When carbon dioxide is run through lime water, the water turns cloudy. This is because the water is a solution of calcium hydroxide, and when it reacts with carbon dioxide, a solid precipitate of calcium carbonate forms.