Wednesday, May 23, 2012

The magic of water to wine to milk then to beer


Wow you must be amaze to see water can change to wine then to milk and then to beer. See Video

Actually is all based on chemical reaction. Below are the chemical that is placed in each glass before doing the demostration. I actually named the glasses A - D.

1.    Glass A (Water) – Pour 110ml of deionised water into the glass. Add in 20ml of saturated sodium bicarbonate with 20% sodium carbonate.
2.    Glass B (Wine) – Add a few ml of phenolphthalein into the wine glass. 
3.    Glass C (Milk) – Pour 25ml of saturated barium chloride solution into the glass.
4.    Glass D (Beer) – Pour 4ml of concentrated hydrochloric acid into the glass. Add in 5ml of bromothymol blue (0.1g in 8ml NaOH and top up to 250ml).

The explaination:

When Glass A is poured into glass B, the colourless water turned red, resembling wine. This is beacause Sodium Bicarbonate and Sodium Carbonate are alkaline which change the Phenophthalein from colourless to deep red (depending on the conc of the phenophthalein, the more concentrated, it will resemble more like wine).

When the ‘wine’ from glass B is poured into glass C, the solution turns milky white, resembling milk. This is because the barium chloride will react with the sodium carbonate to form barium carbonate which is a white precipitate and make the solution turns white and resemble milk. Since it is not alkaline anymore the phenophthalein change back to colourless.

When the solution from glass C is poured into glass D, the solution turns into a clear yellow solution with bubbling, resembling beer.This is because the barium carbonate reacts with the acid, forming soluble barium ions, water, and carbon dioxide gas. The white solid dissolves, the carbon dioxide creates bubbles. The bromthymol blue which turns yellowish-brown in acidic solution, gives the colour of beer.

Tuesday, May 22, 2012

Elephant toothpaste

Hmm nothing special to mention on as I think it has been featured in alot of video. However in case you do not know the theory behind it, let me explain it. The procedure mentioned below is what I used for the video.

Firstly, we need to add in 30ml of 30% H2O2 in a 100ml measuring cylinder. Add one squirt of dish washing detergent. Then the most exciting part is the 2M potassium iodide. Once a few ml of it is added, the foam will form. Blue dye added is optional as it only give you a nicer colour.

The reaction behind it is due to the potassium iodide which act as a catalyst to break down the hydrogen peroxide to oxygen and water. The oxygen produced caused the liquid detergent to generate bubbles/foam which is what you will see. Do note the reaction is exothermic, so please do not touch as it is quite hot and H2O2 is also quite corrosive in case not all have been reacted.

Anyway enjoy the video and you can try it yourself if you have the chemical needed.

Flame test for Cation

Having difficulty controlling the amount of NaOH and Aq Ammonia used during the Cation test? Try this, just spray the cation solution on the flame and you will be able to identify it. If you do not have a spray bottle, get a metal innoculating loop and dip that into the cation solution, you will be able to see the colour change of the flame.

These are the result of the colour of the flame based on the cation. See the video that I have tried. Enjoy!

Copper - Green
Sodium - Orange
Potassium - Lilac
Barium - Yellow
Calcium - Red

Monday, May 14, 2012

Reaction Between Conc Sulfuric Acid and Potassium Permanganate


Hi, here is an interesting video on the reaction of Conc sulfuric acid and potassium permanganate. 
Conc sulfuric acid is added into a boiling tube (please hold the tube with a retort stand instead of your hand as the reaction can be quite explosive so please handle it with care) followed by a layer of 95% denatured ethanol on it. Then use a forcep to add it some potassium permanganate (add abit will do, do not add a spatula of it as the reaction may be too vigorous and cause explosion.
Once the permanganate dissolved in the sulfuric acid, you will be able to see spark appearing in the layer of ethanol. So what is the theory behind it that causes these reaction?
Concentrated sulfuric acid reacts with KMnO4 to give Mn2O7, which can be explosive. This reaction also produce some ozone which has a high oxidising power which oxidises the ethanol causing it to combust. Therefore together with the explosive Mn2O7, it create spark inside the boiling tube.


You can also try to soak a filter paper with ethanol and over a beaker of conc sulfuric acid and KMnO4 the ozone created can also oxidises the ethanol in the paper and cause it to combust.