- Acids and bases, Solubility, and Precipitation
- Barium Nitrate solution, Ba(NO3)2, saturated, 8-10 mL
- 5 -Beral-type pipets
- 6 -Glasses or Beakers, 400-mL
- Phenolphthalein solution, 1%
- Sodium bicarbonate, NaHCO3, 1 g
- Sodium Hydroxide solution, NaOH, 0.1 M, 10 drops
- Sodium Hydroxide solution NaOH, 6 M, 5-6 mL
- Sulfuric Acid solution H2SO4, 9 M, 1.5 mL
- Water, distilled or deionized, 200 mL
Prior to audience arrival, prepare and label six glasses or beakers as follows:
- Glass 1: "water"- 200 mL of distilled or deionized water and 3-4 drops phenolphthalein solution.
- Glass 2: "fruit punch"- 10 drops of 0.1 M NaOH solution.
- Glass 3: "water"- 1.5 mL of 9 M H2SO4 (sulfuric acid) solution.
- Glass 4: "7-up"- 1 g of NaHCO3(sodium bicarbonate) and 1 pipet (2-3 mL) of water: swirl gently
- Glass 5: "milk"- 3 pipets (8-10 mL) of saturated Ba(NO3)2 (barium nitrate) solution.
- Glass 6: "strawberry milk"- 2 pipets (5-6 mL) of 6 MNaOH solution (must be sufficient to overcome or neutralize the acid).
- Begin by showing that the liquid in glass 1 "water" is colorless.
- Pour the contents of glass 1 into glass 2.
- Pour the contents of glass 2 into glass 3.
- Pour the contents of glass 3 into glass 4 and swirl gently.
- Wait for fizzing to stop and pour glass 4 into glass 5.
- Pour contents of glass 5 into glass 6.
Last night for dinner I could not decide what I wanted to drink with my meal, so I decided to make all of my favorite drinks and drink them all.
Phenolphthalein is an acid-base indicator that turns pink in the presence of a base, and remains colorless in the presence of an acid. Glass 1 contained phenolphthalein and water. It remained colorless because phenolphthalein is colorless in a neutral environment. Glass 2 containes sodium hydroxide, which is a base. Phenolphthalein turns pink in the presence of a base, so it looked like "fruit punch" when glass 1 was poured into it.
Glass 3 contained sulfuric acid, which is an acid. The sulfuric acid neutralizes the base of Naoh in glass 2. Phenolphthalein is colorless in the presence of an acid, so it looked like "water". Glass 4 contained sodium bicarbonate. The sulfuric acid from glass 3 reacts with the sodium carbonate and creates bubbles of CO2 gas, which is the fizzing we saw and looked like "7-up".
The saturated barium nitrate solution in glass 5 also reacts with sulfate ions from the sulfuric acid and forms barium sulfate, which is a cloudy white precipitate and looks like "milk". The last glass contained phenolphthalein and sodium hydroxide, which is a base. The sodium hydroxide neutralizes any remaining sulfuric acid. As previouslystated, phenolphthalein turns pink in the presence of a base, so the cloudy pink solution looked like "strawberry milk".
Do not drink any of the solutions. Avoid body tissue contact with all solutions. Where goggles and gloves.
Flush final solution down drain with water.
- Charles Ophardt, Professor Emeritus, Elmhurst College; Virtual Chembook