Background:
The reaction is: Na2CO3 (aq) + 2 HCl (aq) --> CO2 (g) + H2O (l)
Hydrochloric acid, HCl, is a strong base solution. Sodium Carbonate, Na2CO3, is a weak base solution. CO2 is a product from the reaction in the form of gas bubbles. H2O is present from the water we added to make the saturated Na2CO3 solution.
The universal indicator is an acid- base indicator that turn blue in the presence of bases and red in the presence of acids. A variety of other colors are displayed that correspond to different pH values, giving the indicator the name Universal.
If the tube is left undisturbed, the rainbow would last as long as a couple weeks before becoming all on e color. This demonstrates the very slow rate of diffusion (for definition see Vocabulary section) in liquids.
Safety First! Wear goggles at all times when using acids or bases. Do not ingest any of the materials you are working with and try to avoid contact with skin.
Hydrochloric acid, HCl, is a strong base solution. Sodium Carbonate, Na2CO3, is a weak base solution. CO2 is a product from the reaction in the form of gas bubbles. H2O is present from the water we added to make the saturated Na2CO3 solution.
The universal indicator is an acid- base indicator that turn blue in the presence of bases and red in the presence of acids. A variety of other colors are displayed that correspond to different pH values, giving the indicator the name Universal.
If the tube is left undisturbed, the rainbow would last as long as a couple weeks before becoming all on e color. This demonstrates the very slow rate of diffusion (for definition see Vocabulary section) in liquids.
Safety First! Wear goggles at all times when using acids or bases. Do not ingest any of the materials you are working with and try to avoid contact with skin.
Vocabulary:
Acid: are solutions that range from 1 up to 7 on the pH scale
Base: are solutions that range from 7- 14 on the pH scale
Neutral: 7 on the pH scale is neutral, in other words water
Strong Acid: strong acids start closer to the lower end (1 or so) of the pH scale since they are more powerful than weak acids
Weak Base: weak bases start closer to 7 on the pH scale since they aren't as powerful as strong bases
Saturated: to be at the most amount of a solid a liquid can hold
Diffusion: means to blend and become all one color
Base: are solutions that range from 7- 14 on the pH scale
Neutral: 7 on the pH scale is neutral, in other words water
Strong Acid: strong acids start closer to the lower end (1 or so) of the pH scale since they are more powerful than weak acids
Weak Base: weak bases start closer to 7 on the pH scale since they aren't as powerful as strong bases
Saturated: to be at the most amount of a solid a liquid can hold
Diffusion: means to blend and become all one color
Procedure:
The graduated cylinder at the beginning contained hydrochloric acid, HCl, which is an acid that causes the indicator to turn red. The saturated Sodium Carbonate solution, Na2CO3, that we added into the cylinder is a base, so it causes the solution at the bottom to turn blue. The Sodium Carbonate is also more dense than the HCl solution so it sinks to the bottom. That is why the bottom of the cylinder is deep blue showing the presence of the denser Sodium Carbonate. The top of the cylinder is red to show the presence of the HCl still present. In the middle of the cylinder the solution will be a range of different colors. The range of colors shows that there is different pH's throughout the solution.
Put 100 mL HCl in 250 mL test tube. Add 3 mL of Universal indicator to HCl. Make saturated Na2CO3 solution. Keep adding Na2CO3 to distilled water until no more can be dissolved. Use pipet to add Na2CO3 to HCl indicator solution. Drop Na2CO3 down the side of the test tube.
Put 100 mL HCl in 250 mL test tube. Add 3 mL of Universal indicator to HCl. Make saturated Na2CO3 solution. Keep adding Na2CO3 to distilled water until no more can be dissolved. Use pipet to add Na2CO3 to HCl indicator solution. Drop Na2CO3 down the side of the test tube.