How to Determine CO2 Levels Using Titration
Discover the concentration of carbon dioxide (CO2) in a substance by using a digital titrator or by titrating manually. Titration is a process in which you measure the amount of base it takes to produce a reaction with an acidic substance and use that to determine the volume of the acid. You can then use math to determine how much Co2 gas was in the acidic substance to begin with.
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Things You'll Need
- Titration table
- Titration cartridge
- Titration receptacle
- Delivery tube
- Graduated cylinder
- Water
- Erlenmeyer flask
- Phenolphthalein indicator powder pillow
- 1-liter plastic bottle
- Deionized water
- Pipet
- Rubber gloves
- 50-percent NaOH solution
- Weighing boat
- Dried KHP
- Volumentric flask
- Buret
Instructions
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Using a Digital Titrator
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1
Estimate the level of carbon dioxide you expect to find in the titrated solution. Refer to a table such as the one provided by the Hach Company to determine the sample volume of titrant and titration cartridge you need.
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2
Slide the titration cartridge into the titration receptacle. Turn the cartridge until it clicks.
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3
Open the cartridge by removing the cap. Insert a delivery tube into the cartridge. Use a straight delivery tube since this titration is done by hand rather than by mounting the titration receptacle on a stand.
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4
Fill a graduated cylinder with the appropriate sample volume of water, using the same table you used in Step 1 to determine the sample volume. Pour the water from the cylinder into an Erlenmeyer flask.
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5
Add one Phenolphthalein indicator powder pillow to the flask and stir with a stirrer rod. If the water turns pink, pour it out, clean out the flask and graduated cylinder, and repeat Step 4. Pink color means there is no carbon dioxide present in the water.
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6
Hold the titration receptacle so that the end of the delivery tube points into the flask. Press the plunger release so that titrant flows into the flask.
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7
Swirl the flask and continue titrating until the solution in the flask turns pink.
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8
Check the counter on the titration receptacle and write down its value.
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9
Multiply the counter value by the digit multiplier found in the table to get the volume of CO2 in the solution.
Using Manual Titration
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10
Fill a 1-liter plastic bottle with 500 mL of deionized water. Use a graduated cylinder to measure the correct amount of water.
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11
Put on rubber gloves and use a pipette to transfer 18 mL of 50-percent NaOH solution into the deionized water. Screw the cap tightly on and swirl the bottle to stir. Add another 500 mL of deionized water to the solution. Close the bottle and swirl to stir.
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12
Weigh the dried KHP into a weighing boat and transfer into a volumetric flask. Add 150 mL of deionized water to the flask and swirl to mix.
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13
Calibrate your pH meter by turning it on, setting it to calibrate and placing it in a buffer solution of 4 pH. Standardize the NaOH solution by putting 50 mL of it into a buret, using a pipet to place 25 mL of the KHP solution into an Erlenmeyer flask, adding three drops of indicator, and releasing the NaOH solution into the flask until the solution in the flask turns pink. Use this data to determine the molarity of NaOH and amount of CO2 in the solution.
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1
Tips & Warnings
NaOH is extremely caustic. Always wear gloves and never touch your eyes or face while working with NaOH.
