Showing posts with label January2009. Show all posts
Showing posts with label January2009. Show all posts
Effusive Volcano
An experiment with balsamic vinegar and baking powder to produce an effusive volcano.
When sodium bicarbonate (baking powder) and acetic acid (the vinegar) react, carbon dioxide (a gas) is released.
This gas can make the vinegar erupt through a narrow opening and allow us to reproduce a volcano.
When sodium bicarbonate (baking powder) and acetic acid (the vinegar) react, carbon dioxide (a gas) is released.
This gas can make the vinegar erupt through a narrow opening and allow us to reproduce a volcano.
How to do the Blue Bottle Chemistry demonstration
Bute Andreea, Decuseară Tatiana, Ispas Miruna
“Vasile Alecsandri” High School, Galati, Romania
In this chemistry demonstration, a blue solution gradually becomes clear. When the flask of liquid is swirled around, the solution becomes blue again. Instructions are given for performing the reaction, the chemistry is explained, and options for making red -> clear -> red and green -> red/yellow -> green color change reactions are explained. The blue bottle reaction is easy to perform and uses readily-available materials.
Materials
• tap water
• two 1-liter Erlenmeyer flasks, with stoppers
• 7.5 g glucose (2.5 g for one flask; 5 g for the other flask)
• 7.5 g sodium hydroxide NaOH (2.5 g for one flask; 5 g for the other flask)
• 0.1% solution of methylene blue (1 ml for each flask)
Procedure
1. Half-fill two one-liter Erlenmeyer flasks with tap water.
2. Dissolve 2.5 g of glucose in one of the flask (flask A) and 5 g of glucose in the other flask (flask B).
3. Dissolve 2.5 g of sodium hydroxide (NaOH) in flask A and 5 g of NaOH in flask B.
4. Add ~1 ml of 0.1% methylene blue to each flask.
5. Stopper the flasks and shake them to dissolve the dye. The resulting solution will be blue.
6. Set the flasks aside (this is a good time to explain the chemistry of the demonstration). The liquid will gradually become colorless as glucose is oxidized by the dissolved dioxygen. The effect of concentration on reaction rate should be obvious. The flask with twice the concentration uses the dissolved oxygen in about half the time as the other solution. A thin blue boundary can be expected to remain at the solution-air interface, since oxygen remains available via diffusion.
7. The blue color of the solutions can be restored by swirling or shaking the contents of the flask.
8. The reaction can be repeated several times.
Safety & Clean-Up
Avoid skin contact with the solutions, which contain caustic chemicals.
he reaction neutralizes the solution, which can be disposed of by pouring it down the drain.
How the Blue Bottle Reaction Works
In this reaction, glucose (an aldehyde) in an alkaline solution is slowly oxidized by dioxygen to form gluconic acid:
CH2OH–CHOH–CHOH–CHOH–CHOH–CHO + 1/2 O2 --> CH2OH–CHOH–CHOH–CHOH–CHOH–COOH
Gluconic acid is converted to sodium gluconate in the presence of sodium hydroxide. Methylene blue speeds up this reaction by acting as an oxygen transfer agent. By oxidizing glucose, methylene blue is itself reduced (forming leucomethylene blue), and becomes colorless.
If there is a sufficient available oxygen (from air), leucomethylene blue is re-oxidized and the blue color of solution can be restored. Upon standing, glucose reduces the methylene blue dye and the color of the solution disappears.
In dilute solutions the reaction takes place at 40-60°C, or at room temperature (described here) for more concentrated solutions.
“Vasile Alecsandri” High School, Galati, Romania
In this chemistry demonstration, a blue solution gradually becomes clear. When the flask of liquid is swirled around, the solution becomes blue again. Instructions are given for performing the reaction, the chemistry is explained, and options for making red -> clear -> red and green -> red/yellow -> green color change reactions are explained. The blue bottle reaction is easy to perform and uses readily-available materials.
Materials
• tap water
• two 1-liter Erlenmeyer flasks, with stoppers
• 7.5 g glucose (2.5 g for one flask; 5 g for the other flask)
• 7.5 g sodium hydroxide NaOH (2.5 g for one flask; 5 g for the other flask)
• 0.1% solution of methylene blue (1 ml for each flask)
Procedure
1. Half-fill two one-liter Erlenmeyer flasks with tap water.
2. Dissolve 2.5 g of glucose in one of the flask (flask A) and 5 g of glucose in the other flask (flask B).
3. Dissolve 2.5 g of sodium hydroxide (NaOH) in flask A and 5 g of NaOH in flask B.
4. Add ~1 ml of 0.1% methylene blue to each flask.
5. Stopper the flasks and shake them to dissolve the dye. The resulting solution will be blue.
6. Set the flasks aside (this is a good time to explain the chemistry of the demonstration). The liquid will gradually become colorless as glucose is oxidized by the dissolved dioxygen. The effect of concentration on reaction rate should be obvious. The flask with twice the concentration uses the dissolved oxygen in about half the time as the other solution. A thin blue boundary can be expected to remain at the solution-air interface, since oxygen remains available via diffusion.
7. The blue color of the solutions can be restored by swirling or shaking the contents of the flask.
8. The reaction can be repeated several times.
Safety & Clean-Up
Avoid skin contact with the solutions, which contain caustic chemicals.
he reaction neutralizes the solution, which can be disposed of by pouring it down the drain.
How the Blue Bottle Reaction Works
In this reaction, glucose (an aldehyde) in an alkaline solution is slowly oxidized by dioxygen to form gluconic acid:
CH2OH–CHOH–CHOH–CHOH–CHOH–CHO + 1/2 O2 --> CH2OH–CHOH–CHOH–CHOH–CHOH–COOH
Gluconic acid is converted to sodium gluconate in the presence of sodium hydroxide. Methylene blue speeds up this reaction by acting as an oxygen transfer agent. By oxidizing glucose, methylene blue is itself reduced (forming leucomethylene blue), and becomes colorless.
If there is a sufficient available oxygen (from air), leucomethylene blue is re-oxidized and the blue color of solution can be restored. Upon standing, glucose reduces the methylene blue dye and the color of the solution disappears.
In dilute solutions the reaction takes place at 40-60°C, or at room temperature (described here) for more concentrated solutions.
Rabid Soda Can and How Soap Works
Carmen Sultan, Consuela Tataru
“Vasile Alecsandri” High School, Galati, Romania
Rabid Soda Can
What you’ll need:
1) can of soda
2) salt
Procedure
1. Spoon some salt into a carbonated soda.
2. Watch as the salt causes the soft drink to foam up and overflow the can!
Note:
Be careful not to make a big mess. You should perform this experiment outdoors.
How Soap Works
What you’ll need:
1)jar
2) oil
3)water
4)dishwashing liquid
Procedure
1. Put some cooking oil and some water in a jar, then secure the lid tightly.
2. Shake the jar, and notice how the water and oil stay separated.
3. Now put a few drops of dishwashing liquid into the jar, and secure the lid again.
4. Shake the jar once again, and notice how a cloudy mixture has been created.
Why?
The dishwashing liquid breaks up the oil into smaller drops, which just float in the water, creating the cloudy mixture. When cleaning, soap allows oil and grime to be washed away better!
“Vasile Alecsandri” High School, Galati, Romania
Rabid Soda Can
What you’ll need:
1) can of soda
2) salt
1. Spoon some salt into a carbonated soda.
2. Watch as the salt causes the soft drink to foam up and overflow the can!
Note:
Be careful not to make a big mess. You should perform this experiment outdoors.
How Soap Works
What you’ll need:
1)jar
2) oil
3)water
4)dishwashing liquid
Procedure
1. Put some cooking oil and some water in a jar, then secure the lid tightly.
2. Shake the jar, and notice how the water and oil stay separated.
3. Now put a few drops of dishwashing liquid into the jar, and secure the lid again.
4. Shake the jar once again, and notice how a cloudy mixture has been created.
The dishwashing liquid breaks up the oil into smaller drops, which just float in the water, creating the cloudy mixture. When cleaning, soap allows oil and grime to be washed away better!
Magic Milk
Gita Diana, Manoliu Raluca, Mirita Livia
“Vasile Alecsandri” High School, Galati, Romania
What You'll Need
Whole milk
Food coloring
Liquid dish soap
Shallow pan (like a pie pan)
Procedure
1. Pour whole milk in a pie pan, and allow the milk to warm to room temperature.
2. Place a few drops of different colored food coloring into the pan of milk.
3. Next, place a few drops of liquid dish soap into the pan of milk.
4. Watch what happens.
Note:
The soap breaks down the fat in the milk and causes the food coloring to swirl and make some really neat designs.
“Vasile Alecsandri” High School, Galati, Romania
What You'll Need
Whole milk
Food coloring
Liquid dish soap
Shallow pan (like a pie pan)
1. Pour whole milk in a pie pan, and allow the milk to warm to room temperature.
2. Place a few drops of different colored food coloring into the pan of milk.
3. Next, place a few drops of liquid dish soap into the pan of milk.
4. Watch what happens.
The soap breaks down the fat in the milk and causes the food coloring to swirl and make some really neat designs.
The oxidation of glucose with Fehling reactive
Irimia Diana, Gherghisan Cristina, Alexandrescu Isabela
“Vasile Alecsandri” High School, Galati, Romania
The necessary Fehling reactive is prepared using:
1) Fehling 1 solution-we dissolve 7g of copper sulphate in 100ml water
2) Fehling 2-we dissolve 35g Seighette salt and 26g potassium hydrate in 100ml water
In the experiment we use equal parts of both solutions.
We introduce in a clean test tube 2-3 ml Fehling reactive and we boil it; meanwhile we drip in the test tube washy glucose solution 20-25% until the blue color of the blend disappears and a red copper oxide precipitate appears.
“Vasile Alecsandri” High School, Galati, Romania
1) Fehling 1 solution-we dissolve 7g of copper sulphate in 100ml water
2) Fehling 2-we dissolve 35g Seighette salt and 26g potassium hydrate in 100ml water
In the experiment we use equal parts of both solutions.
We introduce in a clean test tube 2-3 ml Fehling reactive and we boil it; meanwhile we drip in the test tube washy glucose solution 20-25% until the blue color of the blend disappears and a red copper oxide precipitate appears.
CuSO4 + 2 KOH = Cu(OH)2 + K2SO4
C6H12O6 + 2 Cu(OH)2 = C6H12O7 + Cu2O + 2 H2O
Glucose --> Gluconic acid
C6H12O6 + 2 Cu(OH)2 = C6H12O7 + Cu2O + 2 H2O
Glucose --> Gluconic acid
Disappearing ink
Barzu George, Hirtan Constantin, Onofrei Octavian, Pamant Alexandru, Popa Ciprian, Sandu Andrei
“Vasile Alecsandri” High School, Galati, Romania
Introduction
A blue liquid is made. This liquid is tested on a white page, it leaves a blue ink spot. In a few seconds, the blue spot disappears.
What to do
1. Place 10 cm3 of ethanol (Highly flammable) in a small beaker.
2. Add a few drops of thymolphthalein (Highly flammable) indicator solution.
3. Add just enough NaOH solution (Irritant), dropwise, to produce a deep blue colour in the solution.
4. Using a small paint brush test the ‘disappearing ink’ on a white page.
Safety
Wear eye protection. Care with teat pipettes that contain sodium hydroxide.
Questions
The colour change occurs because sodium hydroxide reacts with a gas in the air.
1. Which gas in the air causes this colour change?
2. Write a word equation for the reaction.
3. Write a formula equation for the reaction.
“Vasile Alecsandri” High School, Galati, Romania
A blue liquid is made. This liquid is tested on a white page, it leaves a blue ink spot. In a few seconds, the blue spot disappears.
What to do
1. Place 10 cm3 of ethanol (Highly flammable) in a small beaker.
3. Add just enough NaOH solution (Irritant), dropwise, to produce a deep blue colour in the solution.
4. Using a small paint brush test the ‘disappearing ink’ on a white page.
Safety
Wear eye protection. Care with teat pipettes that contain sodium hydroxide.
Questions
The colour change occurs because sodium hydroxide reacts with a gas in the air.
1. Which gas in the air causes this colour change?
2. Write a word equation for the reaction.
3. Write a formula equation for the reaction.
Carbon Dioxide Production
As we know when sodium bicarbonate (baking powder) and acetic acid (the vinegar) react, carbon dioxide (a gas) is released.
Since carbon dioxide is a gas, as the quantity of gas increases, likely does its volume (PV=nRT).
The reaction of vinegar with baking powder, can fill a balloon as carbon dioxide is released from the reaction.
Since carbon dioxide is a gas, as the quantity of gas increases, likely does its volume (PV=nRT).
The reaction of vinegar with baking powder, can fill a balloon as carbon dioxide is released from the reaction.
The egg without shell
Adrian Filimon, Roxana Rovenţa
“Vasile Alecsandri” High School, Galati, Romania
What you need:
1 egg (hard boiled is less messy if you accidentally break it, but you can use a raw one)
1 cup vinegar
clear jar or glass
Optional: Soft Shelled Eggs Printable Activity Sheet
Directions:
1)Pour 1 cup of vinegar into jar
2)Add the egg
3)Record what you see (bubbles rising from the egg)
4)Leave the egg in the vinegar for one day.
5)Remove the egg and feel it.
6)Record your observations (the egg shell will be soft)
What happened:
Eggs contain something called "calcium carbonate". This is what makes them hard.
Vinegar is an acid known as acetic acid.
When calcium carbonate (the egg) and acetic acid (the vinegar) combine, a chemical reaction takes place and carbon dioxide (a gas) is released. This is what the bubbles are made of.
The chemical reaction keeps happening until all of the carbon in the egg is used up- it takes about a day.
“Vasile Alecsandri” High School, Galati, Romania
What you need:
1 egg (hard boiled is less messy if you accidentally break it, but you can use a raw one)
1 cup vinegar
clear jar or glass
Optional: Soft Shelled Eggs Printable Activity Sheet
Directions:
1)Pour 1 cup of vinegar into jar
2)Add the egg
3)Record what you see (bubbles rising from the egg)
4)Leave the egg in the vinegar for one day.
5)Remove the egg and feel it.
6)Record your observations (the egg shell will be soft)
What happened:
Eggs contain something called "calcium carbonate". This is what makes them hard.
Vinegar is an acid known as acetic acid.
When calcium carbonate (the egg) and acetic acid (the vinegar) combine, a chemical reaction takes place and carbon dioxide (a gas) is released. This is what the bubbles are made of.
The chemical reaction keeps happening until all of the carbon in the egg is used up- it takes about a day.
The Fire Extinguisher
By David Arez
Escola Secundária de Loulé Portugal
Escola Secundária de Loulé Portugal
This is movie about the functioning of carbon dioxide fire extinguishers.
If oxygen is removed by a gas that isn't combustive then the combustion reaction comes to an end.
If oxygen is removed by a gas that isn't combustive then the combustion reaction comes to an end.
Subscribe to:
Posts (Atom)