Classification of Haloalkanes

Question: How do you classify haloalkanes (alkyl halides) as primary, secondary or tertiary?

Answers at https://www.ausetute.com.au/rxclassify.html

Test your knowledge of how to classify haloalkanes with AUS-e-TUTE's games and tests (with instant feedback and worked solutions!). Find out more at https://www.ausetute.com.au/register.html

Alkanol + HX

What happens when you add a concentrated hydrohalic acid, like hydrobromic acid or hydrochloric acid or hydroiodic acid, to an alkanol?
A substitution reaction!
Find out more in AUS-e-TUTE's new tutorial at https://www.ausetute.com.au/alkanolhx.html

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

Saturation

What does it mean when a Chemist refers to a molecule as saturated or unsaturated?
How do you test a compound to see if it is saturated or unsaturated?
The answers to these questions, with examples, are given in AUS-e-TUTE's new tutorial Saturated and Unsaturated Organic Compounds

AUS-e-TUTE Members should log-in to access the game, test and exam (with worked solutions) on this topic.

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).

Classification of Organic Reactions

Organic reactions are reactions in which the reactants and products are carbon-containing compounds, or organic compounds.
The chemical reactions that organic compounds take part in can be classified as:

• substitution reactions
• addition reactions
• elimination reactions
• oxidation reactions
• reduction reactions
• polymerisation reactions
• rearrangement reactions

AUS-e-TUTE has just added new resources including  a tutorial, game and test with worked solutions to help you identify and classify these types of organic reactions. AUS-e-TUTE Members should log-in to use these new resources.

If you are not an AUS-e-TUTE, a free-to-view tutorial is currently available at https://www.ausetute.com.au/organicrxn.html

Properties of Nitriles

Why are the physical properties, such boiling point and solubility, of an alkanenitrile so similar to that of a primary alkanol with the same number of carbon atoms in the hydrocarbon chain?
Why do alkanenitriles react with so many different reactants?
AUS-e-TUTE has just added new resources to help you understand the physical and chemical properties or alkanenitriles.
AUS-e-TUTE Members should log-in to use the new tutorial, game and test (with worked solutions).
If you are not an AUS-e-TUTE Member you can access a "free-to-view" tutorial at https://www.ausetute.com.au/nitriles.html

Properties of Aldehydes and Ketones

Aldehydes and ketones contain the same functional group, for example, butanal and butanone both contain the same carbonyl functional group (C=O). So how would you tell if a substance was butanal or butanone?
AUS-e-TUTE has just added new resources to help you understand the similarities and differences in the chemical and physical properties of aldehydes and ketones (as represented by alkanals and alkanones). AUS-e-TUTE Members should log-in to use the new tutorial, game, test and exam with worked solutions.
If you are not an AUS-e-TUTE member there is currently a "free-to-view" tutorial on this topic at https://www.ausetute.com.au/ketones.html

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

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

Rosalind Franklin and the Structure of DNA

Three men, James Dewey Watson,  Francis Harry Compton Crick and Maurice Hugh Frederick Wilkins, shared the The Nobel Prize in Physiology or Medicine 1962 "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material.", that is, they  modeled DNA as a double helix, each strand of the helix has a backbone of  sugar molecules held together by phosphate groups. The two strands are twisted together and held together by hydrogen bonds. But how did they learn what DNA was made up of?

 This is where Rosalind Elsie Franklin enters the story of DNA. In 1951 she was a Research Associate at Kings College London where she worked on  X-ray diffraction studies with her colleague Maurice Wilkins. Her x-ray diffraction images of DNA led to the discovery of the DNA helix. The image on the left is known as "photograph 51" and was an x-ray diffraction image of DNA obtained by Franklin's Ph.D student Raymond Gosling.

X-ray diffraction is an instrumental technique used to elucidate the structure of crystals of chemical compounds. Incoming x-rays are diffracted by the crystal lattice and they exit the crystal at different angles. An x-ray crystallographer like Franklin can measure the angles and intensities of these diffracted x-rays to produce a 3-dimensional picture of the density of electrons in the crystal lattice. The electron density can then be used to determine the locations of atoms within the crystal lattice.

Without Franklin's knowledge, Maurice Wilkins showed this image to James Watson who used it, along with other evidence, to develop a model of DNA. Science historians still debate whether Franklin would have determined the structure of DNA on her own had her images not been shared with Watson.

Rosalind Franklin made important scientific contributions, not only to the discovery of the structure of DNA and RNA, but also in helping us to understand the structure of viruses, coal and graphite.
Unfortunately, Rosalind Franklin died of ovarian cancer in 1958. Nobel Prizes are not generally awarded posthumously so her contribution to the elucidation of the structure of DNA is not well-known.


Further Reading:
Chemistry of DNA
Intramolecular Forces
Intermolecular Forces

Suggested Study Questions:

1. Explain the terms crystalline and amorphous.
2. Give an example of a crystalline substance and an example of an amorphous substance.
3. Explain why DNA had to be crystallised before useful information could be obtained using x-ray diffraction.
4. What does the abbreviation DNA stand for?
5. What are the 4 principle bases that make up DNA?
6. These principle bases occur in pairs; what are these 2 pairs?
7. What kind of chemical bonds act between the atoms making up each base in a strand of DNA?
8. What kind of chemical forces join one of the bases on one strand of DNA to its corresponding pair on the other strand of DNA?
9. If you wanted to separate the 2 strands of a DNA double helix, what sort of chemical bonds would you need to break?
10. If you wanted to separated each base from the backbone of sugar molecules, what sort of chemical bonds would you need to break?

Mass Spectroscopy and Organic Molecules

What happens when an organic chemist makes a new molecule?
How do they know what the structure of the new molecule is?
They use lots of different techniques to determine the molecular mass and structure of the new molecule, one of which is mass spectroscopy.
Mass spectroscopy tells you the molecular mass of the molecule, and, it gives a good indication of how the atoms making up the molecule are put together. And it does this by breaking the molecule up!
Find out more about how mass spectroscopy can be used to determine the structure of organic molecules in our tutorial
AUS-e-TUTE Members can log-in to play the corresponding game, and to answer test and exam questions (which give you immediate feedback about 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.

 

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.

Stinky Socks and Shmelly Shirts?

Northumbria University researchers have identified six volatile organic compounds on dirty socks and t-shirts which are responsible for the stench of your dirty laundry. Surprisingly, some of these compounds can survive washing in a machine with detergent at 20°C, that is, washing in cold water will not remove all the compounds responsible for the smell.

The researchers wanted to identify the volatile organic compounds from dirty clothes before washing, after washing while still wet, and after drying, to see which compounds are responsible for bad smells and to see if they were eliminated during the washing process.

6 men and 2 women were each given a new pair of socks. Each person was asked to wash their feet and dry them before wearing the socks for at least 10 hours in a specified type of shoe. Each sock was then placed in a separate bag and stored in the dark overnight. 9 men were each given a t-shirt to wear for 2-3 hours while taking part in a soccer match. After the match the t-shirts were bagged separately and refrigerated.

The researchers smelled each item and graded it on a scale of 0 (no bad smell) to 10 (very bad smell).
Then the items were washed in a Tergotometer, a lab machine made up of several miniature washing machines, at 20°C using non-perfumed detergent. Each item was graded for odour after washing while still wet and then again after drying.

Using analytical techniques like gas chromatography, the team identified 6 main volatile organic compounds that contribute to the smell of dirty laundry:

• butanoic acid (butyric acid); rancid butter odour
• dimethyl disulfide; onion-like odour
• dimethyl trisulfide; powerful, unpleasant odour
• heptan-2-one (2-heptanone); fruity odour like bananas
• nonan-2-one (2-nonanone); herbaceous odour
• octan-2-one (2-octanone); apple-like odour

As the concentration of these volatile organic compounds decreased after each washing, the items became less smelly.


Reference:
Chamila J. Denawaka, Ian A. Fowlis, John R. Dean. Source, impact and removal of malodour from soiled clothing. Journal of Chromatography A, 2016; 1438: 216 DOI:10.1016/j.chroma.2016.02.037

Further Reading:
Scientific Method: http://www.ausetute.com.au/scientificm.html
Experimental Design: http://www.ausetute.com.au/experimentd.html
Writing Lab Reports: http://www.ausetute.com.au/labreport.html
Introduction to Functional Groups: http://www.ausetute.com.au/fungroup.html
Naming Alkanoic Acids: http://www.ausetute.com.au/namalkacid.html
Naming Alkanones: http://www.ausetute.com.au/namalkanone.html
2-Dimensional Structural Formula: http://www.ausetute.com.au/structural2D.html
Condensed Structural Formula: http://www.ausetute.com.au/condensedsf.html
Molecular Formula: http://www.ausetute.com.au/molecularformula.html
Molar Mass Calculations: http://www.ausetute.com.au/moledefs.html
Gas Chromatography (GC) : http://www.ausetute.com.au/gc.html

Suggested Study Questions:

1. What hypothesis was being tested by the researchers in this experiment?
2. Write an aim for the experiment conducted by the researchers.
3. Write a method for this experiment as a series of steps.
4. Tabulate the results of this experiment.
5. Write a suitable conclusion for this experiment.
6. Discuss how you could improve this experiment.
7. Give the 2-dimensional structural formula for each of the following compounds:
• butanoic acid
• heptan-2-one (2-heptanone)
• nonan-2-one (2-nonanone)
• octan-2-one (2-octanone)
8. On each structural formula above, circle the functional group and name it.
9. Classify each of the compounds listed in question 1 on the basis of their functional groups.
10. Give the molecular formula for each of the following compounds:
    • butanoic acid
    • heptan-2-one (2-heptanone)
    • nonan-2-one (2-nonanone)
    • octan-2-one (2-octanone)
11. Give the condensed structural formula for each of the following compounds:
    • butanoic acid
    • heptan-2-one (2-heptanone)
    • nonan-2-one (2-nonanone)
    • octan-2-one (2-octanone)
12. Calculate the molar mass for each of the following compounds:
• butanoic acid
• heptan-2-one (2-heptanone)
• nonan-2-one (2-nonanone)
• octan-2-one (2-octanone)
13. Which of the following do you think would have the longest gas chromatography retention time ? Explain your answer.
    • heptan-2-one (2-heptanone)
    • nonan-2-one (2-nonanone)
    • octan-2-one (2-octanone)
14. Why is gas chromatography (GC) a good choice of analytical technique for this experiment compared to other chromatographic techniques?

Lipstick Evidence

Lipstick is sticky stuff!
Kissing someone on the cheek with your lusciously lipsticked lips will invariably leave a colourful impression. And, after you've had your sip of coffee your "lips" are left behind in vivid colour on the cup. Lipstick can even end up on tissues after  a momentary touch as you blow nose, or wipe tears from your eyes. And we've all seen movies in which a wife discovers lipstick (not her own) on her husband's collar. Needless to say then that lipstick can be found at a crime scene and is considered to be an example of "trace evidence".
Researchers at  Western Illinois University have been investigating better ways to lift and analyse this lipstick evidence.
In general, lipstick is composed of

•     65% castor oil
•     15% beeswax
•     10% other waxes
•     5% lanolin (also known as wool wax or wool grease)
•     5% dyes, pigments and perfume

In other words, most of the mass of a lipstick is made up of lipids (fats, oils and waxes).
To lift the lipstick from the material, the researchers developed a two part process:

1.   Add an organic solvent to remove most of the oils and waxes.
2.   Add a basic organic solvent to extract the remaining residue.

The components of the lipstick are now present in solution.
In order to determine the chemical composition of the solutions, they will need to undergo separation and analysis. Three common methods of doing this are:

• thin layer chromatoagraphy (TLC)
• gas chromatography (GC)
• high performance liquid chromatography (HPLC)

Different brands of lipsticks have different chemical compositions so they produce different chromatographs.
Using known brands and colours of lipsticks, the researchers can produce a database of chromatographs. When lipstick evidence is found at the scene of a crime, forensic scientists can produce a chromatogram of it and compare this with the database of known brands and colours in order to find a match. In this way forensic scientists can determine the brand and colour of the lipstick. Law enforcement officials could then investigate whether a suspect uses that particular lipstick.
The researchers are still performing analyses of lipsticks, but at this stage they have reported that the best results are achieved with gas chromatography (GC).

Reference:
American Chemical Society. "Tying lipstick smears from crime scenes to specific brands." ScienceDaily. ScienceDaily, 14 March 2016.

Further Reading:
Percentage composition 
w/w % concentration
Parts per million (ppm) concentration
Lipids (oils, fats and waxes) 
Properties of Carboxylic Acids 
Preparation and Naming of Simple Esters


Suggested Study Questions:

1. A tube of lipstick contains 4.0 grams of lipstick. Calculate the mass of each of the following components of the lipstick:
   
   • castor oil
   • beeswax
   • lanolin
2.  The castor oil used to make the 4.0 grams of lipstick is itself made up of a number of fatty acids notably about 90% ricinoleic acid, 4% oleic acid and 3% linoleic acid. Calculate the mass of each of these fatty acids present in the lipstick.
3. Why do you think the concentrations of chemical compounds found in lipstick are given as % w/w (percentage by weight or percentage by mass) rather than in units of mol L^-1 or ppm?
4.  What is meant by the term "fatty acid" in chemistry?
5.  Draw and name the functional group that is present in both carboxylic acids and fatty acids.
6.  Acetic acid (ethanoic acid) is miscible (soluble in all proportions) in water,  whereas the solubility of pentanoic acid is 3.4 g mL^-1, and of hexanoic acid is 1.0 g mL^-1. Would you expect oleic acid (C₁₇H₃₄O₂) to be soluble in water? Explain your answer.
7.  What is meant by the term "triglyceride" in chemistry?
8.  Draw the functional group that is common to both triglycerides and esters.
9.  Esters are immiscible in water so an organic solvent is used to extract the triglycerides from the lipstick marks. Imagine you have been given samples of cyclohexane, ethanol, and acetone. Which of these do you think would be the best solvent to use on the lipstick mark, and explain your answer.
10.  Design an experiment that you could perform to test your hypothesis in question 9 above regarding which of the solvents would be best to use on the lipstick mark.

Cheesy Chemistry

Now here's the title of an article that sounds like it would make a great teaching and learning tool ..
"Food hacks: The science behind making perfect cheese melts and crispy cookies"
(Sydney Morning Herald, Monday 23rd November 2015)

"Science is great isn't it? ", writes the article's author.
Yes indeed, I couldn't agree more ... looks promising .....

"Even for those of us who find the periodic table of elements a foreign language, we can still reap the benefits of science's life-changing revelations."
Well, that's going a bit far (especially if you happen to teach/learn chemistry), but even so,  it still looks OK ......

"According to science, there's only one type of cheese for your toastie."
...mmm... possibly ...... "science" is rarely capable of making that kind of judgement ..... but we'll continue reading ....

until ........

" That cheese is the one with the right PH to balance the calcium, and release the casein (dairy protein) to create one big soft melty​ mess."
PH? Is that some kind of special food science thing? Could it be phosphorus monohydride?
No, it appears to simply be a mistake, which was, unfortunately repeated on the following line.
The author was referring to pH.

Nevertheless, did you know that different cheeses have different pH values?
I didn't!
So off I went to find the pH of some of my favourite cheeses:

cheese	pH
camembert	7.44
cheddar	5.90
cottage	4.75-5.02
cream	4.10-4.79
edem	5.40
gruyere	5.68-6.62
parmesan	5.20-5.30
stilton	5.70

Apparently, pH and temperature are both critical factors in the production of cheese:

• Addition of starter culture: temperature less than 20°C, pH = 5.1-5.3 (using rennet which contains enzymes for breaking down proteins)
•  Coagulation: temperature = 30°C, pH = 5.35 - 5.45
• Pressing: temperature 16-18°C (mild cheeses) or 25°C (hard cheeses), pH = 5.0-5.3
• Brining in salt solution: temperature 15°C, pH = 5.2
• Ripening: pH increases to optimum value as given in the table above.

A crumbly cheese, like a Cheshire cheese, has a low pH and low calcium content. At low pH the colloidal calcium phosphate between casein micelles becomes soluble and the size of these protein aggregates decreases, which, makes the cheese crumbly.

A low-acid cheese (high pH cheese) like Swiss cheese, has intact casein micelles which provide an extensive string of protein aggregates giving the cheese more elastic properties.

Further Reading:
http://www.ausetute.com.au/phscale.html
http://www.ausetute.com.au/phcalcs.html
http://www.ausetute.com.au/phhcalcs.html 
http://www.ausetute.com.au/enzymes.html 
http://www.ausetute.com.au/proteins.html
http://www.ausetute.com.au/aminoacid.html
http://www.ausetute.com.au/scientificm.html
http://www.ausetute.com.au/labreport.html


Suggested Study Questions:

1. What is meant by the term pH ?
2. Calculate the hydrogen ion concentration for each of the cheeses listed in the table above.
3. Arrange the cheeses in the table from lowest to highest pH.
4. Arrange the cheeses in the table from lowest hydrogen ion concentration to highest hydrogen ion concentration.
5. What is an enzyme?
6. What is a protein made up of?
7. Why do you think the temperature of the mixture during the addition of rennet and the coagulation stages is higher than at other stages during the production of cheese?
8. "According to science, there's only one type of cheese for your toastie."
    Do you think science can really tell you the best cheese to use for your toastie? Why or why not?
9. Who do you think the intended audience of this article is? Explain your answer.
10. Imagine you have just tested the pH the of various cheeses and that it is your results shown in the table above. Rewrite this article as if it were your lab report.
    

Alkanols vs Alkanals

Question: Differentiate between alkanols and alkanals.

Answer: Alkanols and alkanals are both organic (carbon containing) compounds but they have different functional groups.
Alkanols contain the OH (hydroxyl) functional group.
Alkanals contain the C=O (carbonyl) functional group on a terminal (end) carbon atom of the carbon chain.
Because they have different functional groups they undergo different chemical reactions and will have different physical properties.
The physical and chemical properties of alkanols, for example, can be found at AUS-e-TUTE's page on Properties of Alkanols.