The active ingredient in household bleach is sodium hypochlorite, but just how much hypochlorite will you find in a litre of bleach?
You can easily find out in your school lab, all it takes is a redox titration, which, ofcourse, you will find at AUS-e-TUTE!
AUS-e-TUTE Members should log-in to the Test Centre to use the new tutorial with drill, game and test.
Visit http://www.ausetute.com.au for a complete list of "free" tutorials available for non-members.
Get information about how to improve your chemistry results at http://www.ausetute.com.au/membership.html
Begin improving your chemistry results at http://www.ausetute.com.au/register.html
Sunday, January 25, 2015
Thursday, January 8, 2015
Aspro, Aspirin, and World War I
2015, a very significant year for all Australians and New Zealanders, marks the centenary of the "Landing at Gallipoli" on 25th April 1914 and the birth of the ANZAC legend. It also marks the centenary of "Aspro" and the birth of a giant international pharmaceutical company that began in Australia as a direct result of World War I.
Felix Hoffman, a German Chemist, first synthesized aspirin, acetylsalicylic acid (2-Ethanoyloxybenzene carboxylic acid), in 1897 while working for the German pharmaceutical company Bayer AG. This was the first major product released by Bayer AG and the trademark Aspirin was registered worldwide. Prior to 1914 Germany exported Aspirin all over the world.
German supplies of Aspirin to Australia (and other countries) were cut off with the outbreak of World War I in 1914, prompting the then Attorney-General W. M. Hughes (and the 7th Australian Prime Minister from 1915 to 1923) to suspend German patents and trademarks and grant them to any Australian-based manufacturer who could meet the requirements for purity and safety.
George Richard Rich Nicholas, a pharmacist who had opened a pharmacy in Punt Road, Windsor in Victoria in 1912, set out to make acetylsalicylic acid. Using kitchen utensils, he measured out quantities of the white salicylic acid powder and the acrid smelling acetic anhydride liquid and reacted them in kerosene tins. Needless to say, although he succeeded in producing acetylsalicylic acid it was impure! With the help of Henry Woolf Shmith, an entrepreneur, the experiments continued until they had pure samples of acetylsalicylic acid. In 1915 their product was tested by the government analyst and found to comply with the requirements of the British Pharmacopoeia so Shmith, Nicholas & Co. were granted a licence to make and sell aspirin in Australia.
Their acetylsalicylic acid product was originally marketed as Nicholas-Aspirin, but George was concerned that the name Aspirin could be reclaimed by Bayer after the war, so, in 1917 the name Aspro was registered.
After the war, in 1921, the name of the company making Aspro was changed to Nicholas Pty Ltd and moved from Windsor to South Melbourne. In 1923, New Zealand began production of Aspro. Between 1925 and 1927 sales of Aspro were expanding in Europe and Asia. In 1927, George's brother Alfred set up the company Aspro Ltd in England, which became a public company in 1935. In 1969 Nicholas Australia Ltd bought out the English Aspro-Nicholas Ltd, which, in 1970, became Nicholas International Ltd. In 1981 Nicholas International Ltd merged with Kiwi International Ltd (makers of the famous Kiwi shoe polish) to form the Australian public company Nicholas Kiwi. In 1984 Sara Lee acquired Nicholas Kiwi, and in 1988 Piramal India acquired Nicholas Laboratories from Sara Lee.
Ready to learn about the chemistry of aspirin and aspro?
Go to the Free Chemistry Tutorial on Aspirin at AUS-e-TUTE to read about the reactions that produced aspirin as well as the physical and chemical properties of aspirin.
(AUS-e-TUTE Members should log-in to the Test Centre and use the "Members ONLY" Aspirin Tutorial).
AUS-e-TUTE members also have access to other learning resources, such as games, tests and exams on the chemistry of aspirin.
Find out about AUS-e-TUTE membership here.
And you can become an AUS-e-TUTE member here, and start improving your chemistry results today!
Felix Hoffman, a German Chemist, first synthesized aspirin, acetylsalicylic acid (2-Ethanoyloxybenzene carboxylic acid), in 1897 while working for the German pharmaceutical company Bayer AG. This was the first major product released by Bayer AG and the trademark Aspirin was registered worldwide. Prior to 1914 Germany exported Aspirin all over the world.
German supplies of Aspirin to Australia (and other countries) were cut off with the outbreak of World War I in 1914, prompting the then Attorney-General W. M. Hughes (and the 7th Australian Prime Minister from 1915 to 1923) to suspend German patents and trademarks and grant them to any Australian-based manufacturer who could meet the requirements for purity and safety.
George Richard Rich Nicholas, a pharmacist who had opened a pharmacy in Punt Road, Windsor in Victoria in 1912, set out to make acetylsalicylic acid. Using kitchen utensils, he measured out quantities of the white salicylic acid powder and the acrid smelling acetic anhydride liquid and reacted them in kerosene tins. Needless to say, although he succeeded in producing acetylsalicylic acid it was impure! With the help of Henry Woolf Shmith, an entrepreneur, the experiments continued until they had pure samples of acetylsalicylic acid. In 1915 their product was tested by the government analyst and found to comply with the requirements of the British Pharmacopoeia so Shmith, Nicholas & Co. were granted a licence to make and sell aspirin in Australia.
Their acetylsalicylic acid product was originally marketed as Nicholas-Aspirin, but George was concerned that the name Aspirin could be reclaimed by Bayer after the war, so, in 1917 the name Aspro was registered.
After the war, in 1921, the name of the company making Aspro was changed to Nicholas Pty Ltd and moved from Windsor to South Melbourne. In 1923, New Zealand began production of Aspro. Between 1925 and 1927 sales of Aspro were expanding in Europe and Asia. In 1927, George's brother Alfred set up the company Aspro Ltd in England, which became a public company in 1935. In 1969 Nicholas Australia Ltd bought out the English Aspro-Nicholas Ltd, which, in 1970, became Nicholas International Ltd. In 1981 Nicholas International Ltd merged with Kiwi International Ltd (makers of the famous Kiwi shoe polish) to form the Australian public company Nicholas Kiwi. In 1984 Sara Lee acquired Nicholas Kiwi, and in 1988 Piramal India acquired Nicholas Laboratories from Sara Lee.
Ready to learn about the chemistry of aspirin and aspro?
Go to the Free Chemistry Tutorial on Aspirin at AUS-e-TUTE to read about the reactions that produced aspirin as well as the physical and chemical properties of aspirin.
(AUS-e-TUTE Members should log-in to the Test Centre and use the "Members ONLY" Aspirin Tutorial).
AUS-e-TUTE members also have access to other learning resources, such as games, tests and exams on the chemistry of aspirin.
Find out about AUS-e-TUTE membership here.
And you can become an AUS-e-TUTE member here, and start improving your chemistry results today!
Wednesday, January 7, 2015
Concentration of Acetic Acid in Vinegar
Here's a strange thing. Most adults wouldn't dream of drinking wine that has been oxidized and "gone bad", just the smell is likely to put most people off! The same people, however, probably have no objection to consuming wine that has been deliberately oxidized, bottled, and marketed as vinegar.
Ofcourse, the chemistry of the oxidation of a mixture like wine is quite complex, but the most important constituent of the mixture is acetic acid (also known as ethanoic acid).
Determining the acidity of your vinegar, or how much acetic acid (ethanoic acid) is present in your vinegar, is quite easy. It's just a simple acid-base titration, and AUS-e-TUTE has just added new resources to help you understand how you can use acid-base titrations to find the concentration of acetic acid in vinegar.
AUS-e-TUTE Members have access to the new tutorial, games, test and exam.
If you are not an AUS-e-TUTE, you can take a sneak peek at the tutorial here
Ofcourse, the chemistry of the oxidation of a mixture like wine is quite complex, but the most important constituent of the mixture is acetic acid (also known as ethanoic acid).
Determining the acidity of your vinegar, or how much acetic acid (ethanoic acid) is present in your vinegar, is quite easy. It's just a simple acid-base titration, and AUS-e-TUTE has just added new resources to help you understand how you can use acid-base titrations to find the concentration of acetic acid in vinegar.
AUS-e-TUTE Members have access to the new tutorial, games, test and exam.
If you are not an AUS-e-TUTE, you can take a sneak peek at the tutorial here
Tuesday, January 6, 2015
Bioethanol Fireplaces
Ethanol burners are becoming very popular in homes in Australia, often sold as "bioethanol" fireplaces. Although how "bio" your ethanol is really depends on which brand of ethanol or methylated spirits you choose to buy.
Having got some advertising mileage out of sticking the prefix "bio" onto ethanol, the glossy advertising brochure then adds some more enticing words like "eco", "friendly", "green" and/or "smart".
But the real selling point of the slick advertising is that you don't need a flue. No chimney, no pipes, just set your "bioethanol" fireplace up where ever you want it in the room.
Which is really very, very, interesting (for all you Chemists out there).
Chemistry of Combustion
Ethanol combusts (burns) by combining with oxygen gas in the atmosphere.
A balanced chemical equation for the complete combustion of ethanol is:
C2H5OH + 3O2 → 2CO2 + 3H2O
This tells us that for every 1 mole of ethanol (whether it has the "bio" prefix or not), 2 moles of carbon dioxide gas will be evolved (and yes, that's the same carbon dioxide gas that contributes to the greenhouse effect).
According to the brochure, 5 litres of "bioethanol" would last about 10 hours.
That is, 1 litre of bioethanol keeps your fire going for about 2 hours, just enough to watch a movie.
So how much carbon dioxide will be released into your room while you watch the movie?
First we can use the density of ethanol and the volume of ethanol burnt to calculate the mass of ethanol consumed:
Now we can calculate the moles of ethanol in the 1 L of "bioethanol" we burnt:
Use the balanced chemical equation to calculate the moles of carbon dioxide produced:
We can then calculate the volume of carbon dioxide released into your room while you watch the movie:
853 L of carbon dioxide gas sounds like lot!
But is it really? What proportion of the "air" in your room will be carbon dioxide after 2 hours?
Let's calculate the volume of a room:
And now we can see what proportion of the "air" in your room will be carbon dioxide after 2 hours:
Or does it?
Did you know that at a concentration of about 1%, carbon dioxide will make you feel sleepy.
At a concentration of about 7%, you can suffocate.
Which makes you think you should probably be opening a window!
Except, wouldn't that defeat the purpose of lighting a fire to keep warm in the first place?
Suggested Study Questions:
Having got some advertising mileage out of sticking the prefix "bio" onto ethanol, the glossy advertising brochure then adds some more enticing words like "eco", "friendly", "green" and/or "smart".
But the real selling point of the slick advertising is that you don't need a flue. No chimney, no pipes, just set your "bioethanol" fireplace up where ever you want it in the room.
Which is really very, very, interesting (for all you Chemists out there).
Chemistry of Combustion
Ethanol combusts (burns) by combining with oxygen gas in the atmosphere.
A balanced chemical equation for the complete combustion of ethanol is:
C2H5OH + 3O2 → 2CO2 + 3H2O
This tells us that for every 1 mole of ethanol (whether it has the "bio" prefix or not), 2 moles of carbon dioxide gas will be evolved (and yes, that's the same carbon dioxide gas that contributes to the greenhouse effect).
According to the brochure, 5 litres of "bioethanol" would last about 10 hours.
That is, 1 litre of bioethanol keeps your fire going for about 2 hours, just enough to watch a movie.
So how much carbon dioxide will be released into your room while you watch the movie?
First we can use the density of ethanol and the volume of ethanol burnt to calculate the mass of ethanol consumed:
- Density of ethanol is 0.79 g cm3 at 25oC
- If we let 1cm3 = 1 mL
- then the mass of 1 mL of ethanol is 0.79 g
- so the mass of 1 L of ethanol = 1000 x 0.79 g = 790 g
Now we can calculate the moles of ethanol in the 1 L of "bioethanol" we burnt:
- moles = mass/molar mass
- molar mass = 2 x 12 + 6 x 1 + 16 = 46 g/mol
- so moles of ethanol in 1 L = 790/46 = 17.2 mol
Use the balanced chemical equation to calculate the moles of carbon dioxide produced:
- From the balanced chemical equation, 1 mole of ethanol burns to produce 2 moles of carbon dioxide gas.
- Therefore, 17.2 moles of ethanol burns to produce 2 x 17.2 moles of carbon dioxide gas.
- moles of carbon dioxide produced = 34.4 moles
We can then calculate the volume of carbon dioxide released into your room while you watch the movie:
- At 25oC, 1 mole of gas occupies a volume of 24.79 L
- So, 34.4 moles of carbon dioxide occupies a volume of 34.3 x 24.79 = 853 L
853 L of carbon dioxide gas sounds like lot!
But is it really? What proportion of the "air" in your room will be carbon dioxide after 2 hours?
Let's calculate the volume of a room:
- A small room is about 3m x 3m x 3m
- or 300cm x 300cm x 300cm = 27,000,000 cm3 = 27,000 L
- So the volume of air in the room before you start burning your ethanol is 27,000 L(ignoring loss of volume due to you and the furniture )
And now we can see what proportion of the "air" in your room will be carbon dioxide after 2 hours:
- Assuming there is no ventilation in the room (all the doors and windows are closed), burning 1 L of ethanol adds about 853 L carbon dioxide gas to the room, so the total volume of gas is now 27,853 L.
- The percentage of that due to the carbon dioxide we have produced is 853/27853 x 100 = 3%
Or does it?
Did you know that at a concentration of about 1%, carbon dioxide will make you feel sleepy.
At a concentration of about 7%, you can suffocate.
Which makes you think you should probably be opening a window!
Except, wouldn't that defeat the purpose of lighting a fire to keep warm in the first place?
Suggested Study Questions:
- Draw a structural formula for ethanol.
- Explain the difference between complete and incomplete combustion of ethanol.
- How you could you tell by observation whether the ethanol in your "bioethanol" fireplace was undergoing complete combustion or incomplete combustion?
- The glossy brochure states that your "bioethanol" fireplace will not produce soot. What does this tell you about the type of combustion occurring in the fireplace?
- If the ethanol in the "bioethanol" fireplace was undergoing incomplete combustion, would the amount of carbon dioxide produced be more or less than that produced during complete combustion?
- Calculate the moles of carbon dioxide gas that would be produced if you burnt 1 L of "bioethanol" fuel in your fireplace in a room that measured 5m x 7m x 3m
- What volume of the room in question 6?
- At 25oC, how many moles of gas are present in this room from question 6?
- What percentage of gas in this room from question 6 would be carbon dioxide after you burn 1 L of "bioethanol"?
- One of your friends suggests that you should take a "bioethanol" fireplace with you on your camping trip because it will be a perfect way to heat your tent. Do you agree with your friend or not? Explain your answer.
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