Homologous Series

What is a homologous series in organic chemistry?
Homologous series refers to a group of compounds that have:

1. the same functional group
2. constant successive differences in composition

The individual molecules making up a homologous series  are referred to as homologues (or homologs).

Find out more about homologous series and homologues at https://www.ausetute.com.au/homologous.html

AUS-e-TUTE Members should log-in to use the new Members Only tutorial, game, test and exam (with worked solutions ofcourse).

Naming Nitriles

How do you name a molecule like H-C≡N?
If you are an inorganic chemist you might call it:

• hydrogen cyanide (hydrogen name)
• hydridonitridocarbon (additive name)
• methylidyneazane (substitutive name)

If you are an organic chemist you might call it:

• hydrogen cyanide (functional class name)
• formonitrile (preferred IUPAC name)
• methanenitrile (substitutive name) 

The CN functional group at the end of a hydrocarbon chain results in a molecule that belongs to a class of organic compounds called nitriles. All nitriles contain a terminal CN group known as the cyano functional group.
AUS-e-TUTE has a new tutorial, game and test to help our members understand and apply IUPAC naming rules to nitriles. Members should log-in to use these new resources.

If you are not a member of AUS-e-TUTE you can access a "free-to-view" tutorial on naming nitriles at https://www.ausetute.com.au/namnitrile.html

Hydroxyacid or Carboxyalkanol?

So, you've learnt how to name organic molecules containing the OH (hydroxy) functional group, and, you can name molecules that have the COOH (carboxyl) functional group, the carbonyl functional group (C=O), and the NH₂ (amine) functional group.
Excellent!
But what happens when there are 2 or more different functional groups on the same molecule?
Can you still name it?
We can help!
AUS-e-TUTE has just added a new tutorial, game, test and exam to help you learn the IUPAC rules and confidently apply them to these sorts of molecules.
AUS-e-TUTE Members should log-in to use the new resources (under Organic Nomenclature).
If you are not an AUS-e-TUTE Member you can view the tutorial for free at
https://www.ausetute.com.au/nam2fung.html

Types of Structural Isomerism

If molecules have the same molecular formula but different structural formulae then they are called structural isomers and are said to display structural isomerism.
But there are different types of structural isomerism:

• chain isomerism (also known as skeletal isomerism)
• position isomerism (also known as regioisomerism)
• functional group isomerism (functional isomerism)

AUS-e-TUTE has just added new resources to help you learn about these types of isomerism and to help you apply this understanding when solving problems in chemistry.
AUS-e-TUTE Members should log-in to use the new tutorial, game and test.
If you are not an AUS-e-TUTE member yet, you can view a tutorial for free at https://www.ausetute.com.au/isomerism.html

Short Chain Fatty Acids?

I came across this story in the Sydney Morning Herald this morning, "A make-or-break moment for what may be a new molecule". Sounds exciting doesn't it. A hint of uncertainty, is it or isn't it a new molecule? What will it "make or break"?

It appears that Charles Mackay, a Professor of Microbiology at Monash Biomedicine Discovery Institute has, "demonstrated that dietary fibre and its breakdown fermented products, the short chain fatty acids (SCFAs) influence gut homeostasis, the composition of the gut microbiota, immune tolerance, and inflammatory responses."  I must apologize, I've never been particularly interested in biology, so I actually have no idea what any of that means, but from the story in the newspaper it appears that Professor Mackay thinks we should be eating more "short chain fatty acids" as are present in fermented foods such as vinegars and hence vegetables pickled in vinegars, and this will help regulate our blood pressure and immune system, keeping us healthy. Good news for me, I love pickled onions and gherkins, and have been known to indulge in sauerkraut and kimchi.

But what on earth is a "short chain fatty acid"?

Now, a fatty acid is a long chain carboxylic acid.
A carboxylic acid is a molecule with a carboxylic acid functional group (COOH) at the end of a hydrocarbon chain.
For example, formic acid is the carboxylic acid which is present in an ant's sting. It has only one carbon atom in the chain, its formula is HCOOH (CH₂O₂)
Acetic acid is the carboxylic acid that gives vinegar it's tang. It has 2 carbon atoms in its chain,

CH₃-COOH (C₂H₄O₂)

But fatty acids have lots of carbon atoms in the chain, common fatty acids have 12 or 14 or 16, or 18 carbon atoms in the chain. These fatty acids (long chain carboxylic acids) are found naturally in the oils and fats of plants and animals. If the long hydrocarbon chain is saturated (contains only single bonds between the carbon atoms in the chain) it is called a saturated fatty acid. If there is one, or more, double bonds between carbon atoms in the long chain then it is referred to as an unsaturated fatty acid.

So a "short chain fatty acid" would be what? A short long chain carboxylic acid? Sounds like nonsense doesn't it? Maybe it's a medium length chain carboxylic acid?

According to wikipedia (which may or may not be a reliable source of information),  a "short chain fatty acid" is a fatty acid with 2 to 6 carbon atoms. Included in wikipedia's list of "short chain fatty acids" are the two carboxylic acids we used as examples above, formic acid (which has only 1 carbon atom in its chain and hence does not actually fit within wikipedia's own definition and hence my concern about the reliability of the information it provides), and, acetic acid. So, a "short chain fatty acid" is in fact NOT a short chain "fatty acid", it is simply a short chain carboxylic acid!

Is the "molecule" new, as claimed by the headline? Most unlikely because:

• "short chain fatty acids" is just a poor description of a group of molecules sharing a carboxylic acid functional group, not just 1 molecule
• we've known about these short chain carboxylic acids for a very, very long time

References:
http://www.smh.com.au/national/a-make-or-break-moment-for-what-may-be-a-new-miracle-molecule-20180216-p4z0ky.html
https://research.monash.edu/en/persons/charles-mackay 
https://en.wikipedia.org/wiki/Short-chain_fatty_acid 

Suggested Study Questions:

1.  Draw the 2-dimensional structure formula for each of the following carboxylic acids:
   • formic acid
   • acetic acid
   • propanoic acid
   • butanoic acid
   • pentanoic acid
   • hexanoic acid
2. Draw a condensed structural formula for each of the carboxylic acids in question 1.
3. Draw a skeletal structural formula for each of the carboxylic acids in question 1.
4. Give the molecular formula for each of the carboxylic acids in question 1.
5. Give the empirical formula for each of the carboxylic acids in question 1
6. Are the carboxylic acids in question best described as saturated or unsaturated? Explain your answer.
7. On each 2-dimensional structural formula, identify, circle and name the functional group common to all the molecules.
8. Draw at least 2 structural isomers with the molecular formula C₅H₁₀O₂
9. Circle the functional groups in the molecules you draw in question 8. Name these functional groups.
10. Choose 2 of the structural isomers drawn in question 8. Would you expect these 2 molecules to have very similar, or very different, physical and chemical properties. Explain your answer.

Triclosan

Triclosan is an organic compound used as an antibacterial and antifungal agent in some products. The structure of triclosan is given below

Triclosan has the systematic IUPAC name of 5-chloro-2-(2,4-dichlorophenoxy)phenol.
Since its development in the 1960s, it has been used as a hospital scrub. Its use spread beyond our hospitals and into our homes where it can be found as an additive in toothpaste, soaps and detergents.
In 2007, University of Michigan School of Public Health undertook a study which found that consumer-grade antibacterial soaps containing Triclosan are just as effective as plain soap for removing bacteria from your hands.
University of Cambridge researchers may have found a new use for Triclosan; as an anti-malarial agent.
Malaria kills more than 500,000 people every year. Unfortunately, malaria parasites are becoming more resistant to the drugs we have been using to treat malaria.. It appears that Triclosan inhibits an enzyme in the malaria parasite and works even in drug-resistant parasites! It is hoped a new anti-malarial drug based on Triclosan can be developed in the future.

Reference:
Elizabeth Bilsland, Liisa van Vliet, Kevin Williams, Jack Feltham, Marta P. Carrasco, Wesley L. Fotoran, Eliana F. G. Cubillos, Gerhard Wunderlich, Morten Grøtli, Florian Hollfelder, Victoria Jackson, Ross D. King, Stephen G. Oliver. Plasmodium dihydrofolate reductase is a second enzyme target for the antimalarial action of triclosan. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-19549-x

Further Reading:
IUPAC Nomenclature (organic): http://www.ausetute.com.au/namctut1.html
Introduction to functional groups: http://www.ausetute.com.au/fungroup.html
Benzene: http://www.ausetute.com.au/benzene.html
Molecular Formula: http://www.ausetute.com.au/molecularformula.html
2-dimensional structural formula: http://www.ausetute.com.au/structural2D.html
Condensed structural formula: http://www.ausetute.com.au/condensedsf.html
Skeletal structural formula: http://www.ausetute.com.au/skeletal.html 
Pure substances and mixtures: http://www.ausetute.com.au/puresubs.html
Solutions concepts: http://www.ausetute.com.au/solutions.html
Percentage composition: http://www.ausetute.com.au/percentc.html
Mass-mole calculations:  http://www.ausetute.com.au/massmole.html
Concentration (molarity): http://www.ausetute.com.au/concsols.html
Parts per million (ppm): http://www.ausetute.com.au/partspm.html
weight/weight (mass/mass) concentration: http://www.ausetute.com.au/weightpc.html

Suggested Study Questions:

1.  Use the skeletal structural formula for Triclosan to draw a 2-dimensional structural formula.
2. On your structural formula, identify each halogen.
3. On your structural formula, identify a hydroxyl functional group
4.  On your structural formula, identify an ether link
5. On your structural formula, identify a benzene ring
6. Give the molecular formula for Triclosan
7.  An antibacterial handwash contains 0.5% by mass Triclosan. For 250 g of this handwash, calculate:
   • mass in grams of Triclosan present
   • moles of Triclosan present
8. Calculate the concentration of Triclosan in the same 250 g of handwash in units of:
   • mol L^-1
   • g/100g
   • parts per million (ppm)
9. Is toothpaste a pure substance or a mixture? Explain your answer.
10. Is Triclosan a pure substance or a mixture? Explain your answer.

 

Betaines

Betaines are found in plants, animals and microorganisms. Rich sources of betaines in the human diet are seafood, spinach and wheat germ or bran. Research is beginning to indicate that betaines are important nutrients for the prevention of chronic disease. Researchers are also interested in incorporating betaines into polymer brushes used for antifouling and lubrication.

Betaines are compounds with a positively charged functional group linked to a negatively charged functional group with an alkyl chain in between. The alkyl chain is often referred to as an alkyl chain spacer.  The general structure of an N-alkyl betaine is shown below:

The first betaine discovered was found in sugar beets in the nineteenth century. This betaine is (trimethylammonio)acetate, also known as trimethylglycine, and its skeletal structure is shown below:

Another example of a betaine is 2-(trimethylammonio)octadecanoate (also known as hexadecylbetaine) with the skeletal structure shown below:

2-(Trimethylammonio)tetradecanoate, or dodecylbutaine or laurylbutaine, is also a butaine and its skeletal structure is shown below:

Betaines are strongly attracted to water molecules because of these two charged functional groups.
The solubility of betaines in water is dependent on the length of the carbon chain, as well as on temperature and pH. 
In acidic solution, betaines acquire a net positive charge and act like a cationic surfactant. In anionic solutions, betaines acquire a net negative charge and act like an anionic surfactant.

Betaines can also be used in polymer brushes which are polymers bound to a surface. Polymer brushes can be used for antifouling and lubrication because the hydration of the ionic groups reduces the ability of other materials to adhere to the surface. 

Researchers at Kyushu University recently investigated a series of alkly chain spacers of different lengths bound to a silicon surface. They found that the polymer brushes swelled in humid air and water. It is believed that this is due to electrostatic repulsion between charged groups, and not dependent on the length of the alkyl chain.
In deionised water, net positive cations and net negative anions are repelled because of the  electrostatic force which causes the chain dimension to expand, whereas they shrink under high ionic strength by a charge screening effect of the bound ions.

Reference:
https://www.sciencedaily.com/releases/2017/08/170821094302.htm

Further Reading
Introduction to Functional Groups
2-Dimensional Structural Formula
Condensed Structural Formula
Molecular Formula
Amino Acids
Surfactants ( as found in synthetic detergents)
Intermolecular Forces and Solubility

Suggested Study Questions

1. Locate and identify each functional group on the skeletal structural formula of
• general formula N-alkyl betaine 
• (trimethylammonio)acetate
• 2-(trimethylammonio)octadecanoate
• 2-(trimethylammonio)tetradecanoate
2. Draw a 2-dimensional structural formula for each of the following molecules:
• (trimethylammonio)acetate
• 2-(trimethylammonio)octadecanoate
• 2-(trimethylammonio)tetradecanoate
3. Write the condensed structural formula for each of the following molecules:
• (trimethylammonio)acetate
• 2-(trimethylammonio)octadecanoate
• 2-(trimethylammonio)tetradecanoate
4. Write the molecular formula for each of the following molecules:
• (trimethylammonio)acetate
• 2-(trimethylammonio)octadecanoate
• 2-(trimethylammonio)tetradecanoate
5. Compare the structure of betaines to that of 2-amino acids. Can N-alkyl betaines be classified as alpha amino acids (2-amino acids) ? Justify your answer.
6. Write chemical equations to describe what happens to an N-alkyl betaine in:
• acidic aqueous solution
• basic aqueous solution
7. Compare the structure of N-alkyl betaines to the surfactants found in synthetic detergents. In what ways are surfactant molecules 
• similar to N-alkyl betaines
• different from N-alkyl betaines
8. Explain how N-alkyl betaines act like 
• a cationic surfactant in acidic aqueous solution
• an anionic surfactant in basic aqueous solution
9. Consider the structure of (trimethylammonio)acetate and 2-(trimethylammonio)octadecanoate. Which molecule do you expect to be more soluble in water? Justify your answer.
10. Consider the structure of (trimethylammonio)acetate and 2-(trimethylammonio)octadecanoate. Which molecule do you expect to be more soluble in paraffin oil? Justify your answer.

Coral Killing Sunscreens

More than a year ago, a study involving marine scientists from Virginia, Florida, Israel, the US National Aquarium and the US National Oceanic and Atmospheric Administration, identified a common chemical component of sunscreens capable of damaging coral reefs.
This chemical is commonly known as oxybenzone and its structure is shown below:

This molecule has the systematic IUPAC name of (2-hydroxy-4-methoxyphenyl)(phenyl)methanone
Notice how every carbon atom (except that of the terminal methyl group, the carbon atom of the methoxy group) is involved in a double bond?
This kind of arrangement leads to some interesting properties. One of these properties is that molecules like this one are good at absorbing UV light. So, oxybenzone is added to products such as plastics, sunscreens, hairsprays, nail varnish and cosmetics like lipstick and mascara, as a UV filter.
Sunscreen lotion can contain between 1 and 10% oxybenzone.
Unfortunately, oxybenzone enters the water when people wearing sunscreens or other cosmetics decide to go for a swim. Researchers estimate that between 6,000 and 14,000 tonnes of sunscreen lotion are emitted into the waters of coral reefs each year.
The same property that makes it ideal as a sunscreen makes it a catastrophe for our coral reefs! Blocking UV light to baby corals causes growth deformities, and worse, the coral becomes encased in its own skeleton and dies.
In 2016, a study of Hawaii's sea waters found the oxybenzone concentration ranged from 0.8 to 19.2 µg/L. A previous study found that oxybenzone concentrations as low as 0.062 µg/L could harm the coral.
Hawaii's government asked swimmers, surfers and divers to avoid using sunscreens that contain oxybenzone as a measure towards protecting their reef.

Reference:
Hawaii targets sunscreens with oxybenzone 

Suggested Study Questions:

1. Draw a molecule of oxybenzone, and, locate and name each functional group. 
2. Give the molecular formula for oxybenzone.
3. Calculate the molar mass of oxybenzone.
4. Draw the 2-dimensional structural formula for oxybenzone.
5. Oxybenzone readily dissolves in ethanol. Explain how oxybenzone can dissolve in ethanol.
6. Oxybenzone does not dissolve in water. Explain why oxybenzone dissolves in ethanol but not in water.
7. Given the data in the article, calculate the mass of oxybenzone that could be emitted into coral reef waters each year.
8. Convert the following concentrations of oxybenzone to concentrations in parts per million
   • 0.062 µg/L
   • 0.8 µg/L
   • 19.2 µg/L
9. Convert the following concentrations of oxybenzone to concentrations in moles per litre (molarity)
   • 0.062 µg/L
   • 0.8 µg/L
   • 19.2 µg/L
10. Assume a 375 g tube of sunscreen lotion contains 10% by mass oxybenzone. Use the data in the article to calculate an "average" number of tubes of sunscreen that washed into the ocean each year. Justify your answer.

Sucralose and Acesulfame potassium

Artificial sweeteners,  especially aspartame, have hit the news headlines once again with PepsiCo's decision to start selling Diet Pepsi without aspartame from August 2015 in the USA. The aspartame is to be replaced by a blend of sucralose and acesulfame potassium.

Sucralose was discovered in 1976 when Shashikant Phadnis at Queen Elizabeth College was asked to "test" a chlorinated sugar compound but he thought he'd been asked to "taste" it, so he did, and found it be very sweet! Sucralose, shown on the right, is synthesised from sucrose in a number of steps in which 3 of sucrose's hydroxyl groups are substituted for chlorine atoms.
Although sucralose is about 300 times sweeter than sucrose, it is not broken down during digestion and therefore does not contribute to ingested calories (kilojoules).
Splenda is a brand name for a common sucralose-based sweetener.


Acesulfame potassium was accidentally discovered in 1967 by German chemist Karl Clauss, who found it to be sweeter than sucrose. It is not as sweet as sucralose, however, and is often used in combination with other artificial sweeteners such as aspartame or sucralose. It has the structural formula shown below:

Acesulfame potassium is currently sold under the brand names Sunette, Sweet One and Sweet 'n Safe and is found in many "sugar-free" foods such as chewing gum, jelly (Jell-O), even in alcoholic drinks.

Reference:
http://www.smh.com.au/business/retail/diet-pepsi-dumps-aspartame-as-consumer-backlash-hurts-sales-20150425-1msz1b.html

Further Reading:

• http://www.ausetute.com.au/sugars.html 
• http://www.ausetute.com.au/proteins.html
• http://www.ausetute.com.au/fungroup.html
• http://www.ausetute.com.au/intermof.html
• http://www.ausetute.com.au/skeletal.html
• http://www.ausetute.com.au/structural2D.html
• http://www.ausetute.com.au/condensedsf.html
• http://www.ausetute.com.au/molecularformula.html

Suggested Study Questions:

1. What is the molecular formula for:
   • sucralose
   • sucrose
   • acesulfame potassium
2. Draw the structural formula for sucrose and circle the hydroxyl functional groups.
3. Draw the structural formula for sucralose and
   • circle the hydroxyl functional groups in red
   • circle the halogen functional groups in green
   • circle any other functional groups blue and name them 
4. What class of compounds does sucrose belong to?
5. Draw the structural formula for acesulfame potassium and identify the functional groups.
6. Is it appropriate to call acesulfame potassium a potassium salt? Explain your answer.
7. Aspartame is the methyl ester of a didpeptide. What functional groups do you expect the aspartame molecule to have? Explain your answer. 
8. Do you expect sucralose and acesulfame potassium to be soluble in water? Explain your answer.

Methanol and the Home-Brewer

In June 2013, a young man in Queensland died as a result of drinking homemade liquor. It is believed that the liquor contained a toxic level of methanol (also known as wood alcohol). Drinking 10 mL of pure methanol can cause permanent blindness, drinking 30 mL of methanol can kill you.

The first step in the production of homemade liquors, is the fermentation of sugar.
Methanol, CH₃OH,is formed during fermentation.
When fermenting 6 kg of sugar dissolved in water for the production of distilled spirits such as whiskey or vodka, the home-brewer (and home-distiller) will typically find that the concentration of methanol in their brew is about 3 parts per million.

Many fruits are used by the home-brewer as the source of sugar to be fermented. Each fruit will lend a distinctive flavour to the final product. But fruits that are high in pectin will produce greater concentrations of methanol. Apples, apricots, guavas, quinces, plums, gooseberries, and citrus fruits like oranges, all contain high levels of pectin, typically more than 1% by mass pectin. Grapes, cherries and strawberries contain low levels of pectin, less than 1% by mass pectin.

Pectin contains  galacturonic acid which has the structural formula shown below:

In pectin, about 80% of the carboxyl groups in galacturonic acid are esterified with methanol. The remaining non-esterified carboxyl groups exist as the acid, or as salts with sodium, potassium or calcium. When pectin is broken down by enzymes during the brewing process, the methyl esters react with water to produce methanol.

The second step in the production of homemade liquor is the distillation step.
This is the crucial step in removing as much of the toxic methanol as possible.
The boiling point of methanol is about 65^oC, but the boiling point of ethanol (the desired product) is about 78^oC. During the distillation process, the first fraction collected should contain the methanol. This fraction should be collected and discarded. The next fraction should contain the desired liquor. It is highly recommended that any distillate collected after about 96^oC also be discarded.


Reference:
http://www.couriermail.com.au/news/queensland/ballandean-man-bill-lynam-who-lost-his-son-joel-to-homemade-liquor-poisoning-is-thankful-that-other-son-joshua-survived/story-fnihsrf2-1226664893229

Further Reading
http://ausetute.com.au/members/alkanolp.html (members only tutorial on alkanols)
http://ausetute.com.au/members/carboxyl.html (members only tutorial on alkanoic acids) 
http://ausetute.com.au/partspm.html 
http://ausetute.com.au/density.html 

Suggested Study Questions:

1. Draw the structural formula for methanol.
2. Locate the functional group present in methanol on the structural formula above. Name the functional group. 
3. At 25^oC methanol has a density of  0.79 g mL^-3. Calculate the mass of methanol present in a lethal dose of pure methanol .
4.  Convert the concentration of methanol given for homemade whiskey into a concentration in g mL^-1.
5. Assume the young man who died drank homemade whiskey. What minimum volume of homemade whiskey did he drink?
6. For galacturonic acid given the:
   • molecular formula
   • molar mass
7.  On the structural formula for galacturonic acid identify and name the functional groups present.
8. Draw the structure for the sodium salt of galacturonic acid.
9. Draw the structure for galacturonic acid esterified with methanol.
10. Give the molecular formula and molar mass for the structure above.
11. Apples contain about 1% by mass pectin. 10 kg of apples are to be used in the production of a homemade liquor. What mass of pectin will be present?
12. Assume exactly 100% of the carboxyl groups in galacturonic acid are esterified with methanol. How many moles of the ester are present in 10 kg of apples?
13. Write an equation representing the reaction between this ester and water to form methanol  and galacturonic acid.
14. How many moles of methanol could be produced by the break down of pectin in 10 kg of apples?
15. Assuming the young man who died had drunk this apple concoction without distilling and removing the methanol, what minimum volume of fermented apple-drink would he have had to have drunk?
16. Why do you think most countries have outlawed home-distilling?

Glow in the Dark Ice

No (chemistry) party is complete without edible "glow in the dark" ice cubes.
To make your ice cubes:

•  open up some tonic water (or a bottle of "bitter lemon")
• pour it into an ice cube mold
• place the mold in the freezer until the tonic water solidifies (freezes)

To make your ice cubes glow in the dark:

• place some ice cubes in a glass of water (or cordial or carbonated beverage)
• place the glass under a UV ("black") light (even strong fluorescent light will work but the effect is not as dramatic!) and turn off the room's lights

Results : your glass of water and ice should glow a nice blue colour.


This is an example of fluorescence, the emission of light by a substance that has absorbed electromagnetic radiation. In the case of the tonic water, there is a compound in the tonic water that absorbs light in the ultraviolet region of the electromagnetic spectrum (wavelength ~ 350 nm), and emits light in the visible region of the electromagnetic spectrum (wavelength ~ 450 nm corresponding to bright blue or cyan).

The compound in the tonic water that fluoresces is known as quinine, with the molecular formula C₂₀H₂₄N₂O₂ and the structural formula shown below:

Quinine occurs naturally in the bark of the cinchona tree which is found in the tropical Andes forests of western South America. Quinine was the first effective treatment for malaria. The first medicinal uses involved drying the bark of the cinchona tree then grinding it into a powder which was then mixed into a drink (often wine), which was then drunk. The effective medicinal ingredient of the bark, quinine, was finally isolated in 1820 by French researchers Pierre  Joseph Pelletier and Joseph Bienaime Caventou.
During World War II, the Axis Powers had control over most of the commercial quinine production centres, so the Allied Powers were cut off from their supply of quinine, a necessary war-time commodity for fighting in the tropics. Then in 1944, the American chemists R.B. Woodward and W.E. Doering succeeded in producing quinine in the laboratory.




Quinine is no longer recommended as a first-line treatment of malaria, instead another plant-derived organic compound is used, artemisinin, but that's a different story.

Further Reading:
Emission Spectroscopy
Empirical Formula
Relative Molecular Mass (molecular weight, formula mass, formula weight)
Percent Composition
Parts per Million Concentration
Functional Groups


Suggested Study Questions:

1. Draw a diagram to describe what happens when quinine absorbs UV light and emits bright blue/cyan light.
2. Imagine you were to view the light emitted by the tonic water through a spectroscope. Draw a sketch of the emission spectrum you would expect to see.
3. Use the molecular formula for quinine to find its empirical formula.
4. Calculate the relative molecular mass (molecular weight, formula mass, formula weight) of quinine.
5. Calculate the percentage of each element present in quinine.
6. Assume a 1L bottle of tonic water contains 15ppm quinine. Calculate the
   • mass of quinine contained in the bottle
   • moles of quinine in the bottle
   • quinine concentration in mol L^-1
7. Using the structural formula for quinine, identify an aliphatic double bond (that is, a double bond that does not occur in an aromatic ring), an aromatic (benzene) ring, and an hydroxyl group