Gifts for Chemists

What do you buy a chemist (professional, teacher, or student) as a gift?
They probably already have a cupboard full of mugs emblazoned with a Periodic Table right?
Ditto the tee-shirt.
Well the good people at Sigma-Aldrich (a company that supplies lab equipment) has a product range which it calls "nerdware", and I think you might find something appropriate there.
Go to http://www.sigmaaldrich.com and use the site's search for nerdware (or click the "Holiday Gifts for Scientists in Your Life" link)
I've already added the umbrella to my Christmas wishlist.

Sigma-Aldrich

Sigma-Aldrich

Sigma-Aldrich

Sigma-Aldrich

Sigma-Aldrich

Sigma-Aldrich

Cholera Vaccine

The holiday season is here, and some friends have decided to visit Panama (where else would an Engineer want to go for a holiday but to the Panama Canal?). One of the diseases they want protection against before traveling there is cholera which is caused by a water-born bacteria. The product they are taking is called DUKORAL® which comes in two parts. The first part part is a glass vial containing a whitish fluid which is the oral vaccine made up of inactivated cholera bacteria, which is probably of interest to the biology students reading this. Chemistry students, however, will be much more excited by the second part; a sachet containing a dry granular powder which is labelled as buffer.
The ingredients listed on the buffer sachet are:

• sodium bicarbonate
• citric acid, anhydrous
• raspberry flavour
• sodium carbonate, anhydrous
• sodium citrate
• saccharin sodium

The instructions for use by adults are:

1. Dissolve the effervescent granules from the buffer sachet in a glass of cool water (approximately 150 mL)
2.  Shake the vaccine vial
3. Add the vaccine to the effervescent (bubbly) solution. Mix well and drink mixture.

And, you have to take two of these doses 1 to 6 weeks apart, and 2 weeks before arrival at your destination.
The good news is that most people should be protected cholera for up to two years, so I guess my friends will make their way back to the tropics next year.

Suggested Reading
 http://www.ausetute.com.au/namiform.html
 http://www.ausetute.com.au/wriiform.html
http://www.ausetute.com.au/acidbase.html
 http://www.ausetute.com.au/buffers.html
http://www.ausetute.com.au/esters.html

Suggested Study Questions

1.  What is another, systematic name for sodium bicarbonate?
2. Give the molecular formula for each of the following:
   • sodium bicarbonate
   • citric acid, anhydrous
   • sodium carbonate, anhydrous
   • sodium citrate
3. Draw a structural formula for each of the following:
   • sodium bicarbonate
   • citric acid, anhydrous
   • sodium carbonate, anhydrous
   • sodium citrate
4. Use chemical terms to explain the relationship between:
   • sodium bicarbonate and sodium carbonate
   • citric acid and sodium citrate
5. Explain what a buffer is.
6. Explain why the dry, granular powder in the sachet was labelled "buffer".
7. Why do you think a buffer is needed for this vaccine to be effective?
8. What type of chemical compound is the "raspberry flavour" likely to be?
9. One molecule responsible for raspberry flavour is shown below:
   
   What 2 reactants would you need to produce to this molecule in the school laboratory?
10. What does the term effervescent mean?
11. Write a balanced chemical equation to show why effervescence is observed when the buffer in the sachet is added to water. 
12. What does the term "anhydrous" mean?
13. Why are some of the buffer sachet's ingredients listed as "anhydrous"?
14. What is the purpose of the saccharin in the buffer sachet?

Mine the Moon!

After The Jade Rabbit lander touched down on the Moon in December 2013, the Chinese space agency publicly suggested establishing mining bases on the Moon.

What could be so valuable that it would warrant the cost of going to the Moon to mine it then bringing it back to Earth to be used?

Gold? No.

Diamonds? No again.

Rare earth elements!

Why have rare earth elements (REE) become so important?

Find out in this edition of AUS-e-NEWS.

If you haven't received your December 2016 issue of AUS-e-NEWS in your inbox, please email us at  

 

The man who proved the moon isn’t cheese

Meet Emeritus Professor Ross Taylor AC, the Australian who analyzed the first moon rock samples in 1969, in Volume 46 Number 4 of the ANUreporter,

"With emission spectroscopy you can put a tiny amount of material into the flame and quickly identify any of 70 different elements from the spectral lines they produce. But those 70 elements could produce 100,000 possible lines," he says.
At 11.45am on 28 July, Taylor received the first samples. By 4pm, he delivered preliminary results to a press conference - significantly faster than the usual scientific process and with much more at stake.
The high-speed analysis had not been without hiccups. Taylor almost missed one of the most significant traits of the moon's chemistry, its significantly lower sodium levels than Earth.
The moon is also rich in chromium, which has a spectral line that almost perfectly disguised the low sodium result. Only moments before the press conference Taylor realised the mistake and corrected it.
"It would have ruined my reputation," he says.

Reference:
The man who proved the moon isn't cheese

Further Reading:
http://www.ausetute.com.au/emissions.html 
http://www.ausetute.com.au/flametest.html

Suggested Study Questions
1/ What is an emission spectrum?
2/ How can you produce the emission spectrum of metallic elements at school?
3/ How is the emission spectrum of an element used to confirm the existence of energy levels in atomic structure?
4/ What is a flame test?
5/ How does a flame test differ from emission spectroscopy?
6/ How is a flame test similar to emission spectroscopy?
7/ "With emission spectroscopy you can put a tiny amount of material into the flame and quickly identify any of 70 different elements from the spectral lines they produce." 
Explain how emission spectroscopy can be used to identify different elements.
8/ "But those 70 elements could produce 100,000 possible lines,"
Explain how such a huge number of lines can be produced from what seems like a much smaller number of elements.
9/ "The moon is also rich in chromium, which has a spectral line that almost perfectly disguised the low sodium result"
Explain how a chromium spectral line could disguise the low sodium result.
10/ Imagine you have helped Emeritus Professor Ross Taylor AC analyse these moon rock samples. Produce a scientific poster to communicate the results of this experiment to your class.

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.
    

Biodiesel

What's the difference between diesel and biodiesel?
I'm glad you asked!
AUS-e-TUTE has just added new resources (tutorial, game, test, exam) to help you learn how to synthesize and characterize biodiesel, as well as to distinguish between diesel and biodiesel.
AUS-e-TUTE Members should log-in to access these new resources: http://www.ausetute.com.au

If you are not an AUS-e-TUTE Member, there is a "free-to-view" biodiesel temporarily available at http://www.ausetute.com.au/biodiesel.html for evaluation purposes.

Want more information about AUS-e-TUTE Membership?
Go to http://www.ausetute.com.au/membership.html

Want to join AUS-e-TUTE?
Go to http://www.ausetute.com.au/register.html

Just want to check out what you can get for free?
Go to http://www.ausetute.com.au

Reaction Schemes

When is a flow chart not a flow chart?
When it's a reaction scheme.
Want to learn about reaction schemes used in organic (carbon chemistry) ?
Good, because AUS-e-TUTE has just added a new tutorial, game, test, and exam to help you learn and understand.

AUS-e-TUTE Members should log-in to use the new resources.

If you are not an AUS-e-TUTE Members, there is a "free-to-view" tutorial currently available for evaluation purposes at:
http://www.ausetute.com.au/schemaorg.html

Want find out more about the benefits of AUS-e-TUTE Membership?
Go to http://www.ausetute.com.au/membership.html

Ready to become an AUS-e-TUTE Member?
Go to  http://www.ausetute.com.au/register.html

Got a question for AUS-e-TUTE?
Go to http://www.ausetute.com.au/contact.html

2015 Nobel Prize in (Bio)chemistry?

The 2015 Nobel Prize in Chemistry was awarded to Tomas Lindahl, Paul Modrich and Aziz Sancar for "mechanistic studies of DNA repair".
Cells have developed mechanisms to repair damaged DNA. Four of these mechanisms are:

• photoreactivation


• dark repair (nucleotide excision repair)


• base excision repair


• mismatch repair

Photoreactivation
In the 1920s Hermann Muller found that X-rays could mutate and kill cells.
In the 1940s Albert Kelner found that visible light could stimulate growth recovery after damage caused by UV light, and this was called photoreactivation.
In 1944 Oswald Avery and co-workers showed that DNA is the material of heredity, and in the 1950s it was recognised that DNA became damaged when exposed to UV light.
Renato Dulbecco suggested photoreactivation was an enzymatic reaction dependent on light, which was demonstrated by Stanley Rupert.
In 1978 Aziz Sancar cloned the E. coli photolyase gene, an enzyme responsible for DNA repair in escherichia coli.
In the 1980s Aziz Sancar showed that photolyase can convert the energy of an absorbed photon into chemistry that produces a localised free radical that initiates thymine dimer splitting.

Dark repair (nucleotide excision repair)
In the 1960s Jane Setlow and Richard Setlow showed that thymine dimers inactivated transforming DNA in Hemophilus influenzae and that this was responsible for the biological effect of UV light.
In 1964 Richard Setlow discovered that thymine dimers disappeared from the irradiated, high molecular weight genomic DNA shortly after exposure to UV light and appeared in the low molecular weight fractions, that is, thymine dimers are excised (removed) from the DNA. This mechanism became known as nucleotide excision repair (NER).
In the 1970s Aziz Sancar working with W. Dean Rupp, developed the Maxicell technique for the rapid identification of proteins.
In 1983 Aziz Sancar used purified proteins to reconstitute essential steps in the nucleotide excision repair (NER) pathway, a "cut and patch" method for DNA repair.
Two proteins (UvrA and UvrB) track along the DNA, UvrA recognises damage and causes UvrB to stop tracking and begin unwinding the effected DNA section. Another protein, UvrC, causes the damaged section to be cut out, and then another protein UvrD, causes UvrB to bind and bridge the gap while it is repaired by resynthesising the removed segment via Pol I.

Base excision repair
In the 1970s Tomas Lindahl showed that DNA has limited chemical stability and that modification of the bases of DNA increased the risk of mutations. High levels of spontaneous cytosine deamination leads to the formation of uracil.

Uracil forms base pairs with adenine, so, high levels of cytosine demanination pose a risk of depleting the genetic material from cytosine-guanine base pairs and replacing them with thymine-adenine.
He identified the E. coli uracil-DNA glycosylase (UNG) as the first repair protein which we now know is one member of a large family of proteins that orchestrate base excision repair (BER).
A DNA glycosylase recognises and cuts the base-deoxyribose glycosyl bond of a damaged nucleotide. DNA glycosylase kinks the DNA and the abnormal nucleotide flips out and is removed and the section can then be repaired.

Mismatch repair
During the synthesis of a new DNA strand, a non-Watson-Crick base pair may be formed which distorts the double-stranded DNA helix. These types of errors are known as mismatches.
In 1983 Paul Modrich and Matthew Meselson showed that DNA methylation directed strand-specific elimination of mismatches in E. coli. Modrich developed an assay to isolate the products of the different repair genes and identify the proteins.

Further Reading:
http://www.ausetute.com.au/dna.html
http://www.ausetute.com.au/enzymes.html

Suggested Study Questions:

1. What does the abbrevaition DNA stand for?
2. What do you think when biochemists refer to damaged DNA?
3.  What is meant by the term enzyme?
4. Why do you think enzymes are required in the mechanisms available within a living cell to repair damaged DNA?
5. What is a free radical?
6. Draw the structural formula of thymine.
7. Draw the structural formula for a possible dimer of thymine.
8. What is meant by the term nucleotide?
9. With reference to DNA, what is meant by a base pair?
10. Show how uracil forms a base pair with adenine.
11. Draw the structure of a cytosine-guanine base pair
12. What do you think is meant by the statement, "cytosine deamination leads to the formation of uracil" (structural formulae may be useful in your explanation but you do not need to include chemical reactions).

Empirical Formula of Magnesium Oxide

It's one of the "classic" experiments in school chemistry, combusting (burning) some magnesium in a crucible to make magnesium oxide.
While the lab questions usually focus on identifying that a chemical change has occurred, and calculating either percentage composition and/or empirical formula of magnesium oxide, I wonder how many students are really thinking about the experiment?
So, AUS-e-TUTE has written a tutorial that (hopefully) will help students think about why certain procedures are followed, and the kinds of errors one can expect.

AUS-e-TUTE members should log-in to use the new tutorial, game and test.

If you are not an AUS-e-TUTE Member, a "free-to-view" tutorial is currently available for evaluation purposes at http://www.ausetute.com.au/mgo.html

Information about AUS-e-TUTE Membership is available at www.ausetute.com.au/membership.html

and you can become an AUS-e-TUTE member at http://www.ausetute.com.au/register.html

Where to Study Chemistry?

Are you thinking about studying chemistry at a university?
How should you choose which university?

For those of you who like lists ("The 10 most jocular jokes", "The 10 cutest cat videos", etc, etc), here is a list of the "best" universities: you can visit http://www.topuniversities.com



Now that you've got that "list thing" out of your system, it's time to think seriously about where you will study chemistry.It's probably a good idea to visit the website of the universities you are interested in and get a feel for what you will be studying, who will be teaching you, and what the research interests of the lecturers are.
I hesitate to suggest this next move, but I know you will have thought of it before me, so here goes...  lots of those lectures will be available on youtube, so you "can test and try and before you buy" so to speak. The reason I hesitate to suggest you do this is that quite a number (possibly a very large number) of these videos should never have been made (well, not without some professional film-making advice, and in a number of instances they would have been improved enormously by the substitution of the lecturer by a professional, or even amateur, actor), or having been made, should not have been released into the public domain. They are often just recorded lectures, no green-screen, no whiz-bang CGI, no bombs going off, no exciting car chases, just lots of information delivered by someone competent to deliver it. If the thought of that excites you, please go and view the videos (and you should certainly study chemistry!), if not, don't bother with the videos, but do visit each university's website.
You should also visit your Careers Adviser, he/she will have lots of information!

Equilibrium Constants and Balanced Chemical Equations

Consider the reaction in which carbon monoxide gas reacts with oxygen gas to produce carbon dioxide gas:

CO_(g) + ½O_2(g) ⇔ CO_2(g)   with equilibrium constant = K₍₁₎ (at temperature = T)

and this reaction:
2CO_(g) + O_2(g) ⇔ 2CO_2(g)   with equilibrium constant = K₍₂₎ (also at temperature = T)

 Is the value of K₍₁₎ the same as the value of K₍₂₎ ?
 Not sure?
That's why AUS-e-TUTE has just added a new set of resources to help you understand this concept!

AUS-e-TUTE members should log-in to view the new Members Only resources.

 If you are not an AUS-e-TUTE member, there is a "free-to-view" tutorial available for evaluation purposes at http://www.ausetute.com.au/kstoichio.html

Find out more about AUS-e-TUTE membership at http://www.ausetute.com.au/membership.html

Become an AUS-e-TUTE Members at http://www.ausetute.com.au/register.html

Science Knowledge Quiz

The Pew Research Centre in Washington DC has just released the results of its survey of what adults in the USA know (or think they know) about science. It appears that very few of those surveyed had any real understanding of waves, and almost no understanding of boiling. But the saddest result of all, I think, is that about one third of those surveyed could not correctly interpret a graph.

You can do the 12 question multiple-choice quiz yourself online at:

http://www.pewresearch.org/quiz/science-knowledge/

When you finish (it won't take long) you will then be taken to a page that gives you the results of your quiz, and puts this in relation to the official survey results.

AlP Rat Poison

Dozens of mysterious sealed silver canisters containing aluminium phosphide have washed up on Australian beaches between 2012 and 2015. The Australian Maritime Safety Authority (AMSA) suspects all the canisters have come from the same ship which dumped or lost its cargo in the Pacific Ocean. Aluminium phosphide is used as a fumigant to poison rats on ships.

When solid aluminium phosphide, AlP, is exposed to water, it releases highly toxic phosphine gas, PH₃, which smells like rotting fish. The chemical reaction can be represented by the balanced chemical equation shown below:
AlP_(s) + 3H₂O_(l) → PH_3(g) + Al(OH)_3(aq)

This is a proton-transfer reaction in which water is acting as Brønsted-Lowry acid by donating a proton to phosphorus. Phosphorus is therefore acting as a Brønsted-Lowry base by accepting a proton from water. Aluminium phosphide will react with acids according to the following chemical
AlP_(s) + 3H⁺_(aq) → PH_3(g) + Al³⁺_(aq)

These reactions make aluminium phosphide a good choice for ridding a ship of rats.
Firstly, as a solid, AlP can easily be stored as pellets in air-tight, water-tight, containers until it is ready to be used. When required, the pellets can be scattered in the effected area . In the humid air aboard ship, the AlP will start reacting to produce toxic phosphine gas, that is, the area will be fumigated. But it is also possible to entice rats to eat AlP pellets mixed with food, in which case it will act as pesticide, because on entering the acidic stomach of the rat, it will produce the toxic phosphine.

Aluminium phosphide is  a very effective way to get ride of rats, so much so, that is widely used in agriculture to remove rats from grain silos.

References:
"Toxic canisters washing up on Australian beaches pose serious health risk"
 http://www.smh.com.au/environment/toxic-canisters-washing-up-on-australian-beaches-pose-serious-health-risk-20150917-gjp5se.html

"Controlling rabbits with aluminium phosphide tablets"
 http://agriculture.vic.gov.au/agriculture/farm-management/chemical-use/publications/chemical-industry-news/chemical-industry-news-no.-75-summer-autumn-2013

"Phosphine fumigation"
https://www.worksafe.qld.gov.au/injury-prevention-safety/hazardous-chemicals/specific-hazardous-chemicals/phosphine-fumigation

Further Reading
Definition of Acids and Bases
Proton-transfer Reactions
Mass-mole Calculations
Molar Volume of Gases

Suggested Study Questions:

1. The symbols of some elements are listed below. Name each element.
   • Al
   • P
   • H
   • O
   • K
   • He
   • At
2. Calculate the amount of aluminium phosphide in moles given the masses of AlP given below:
   • 10 g
   • 10 kg
   • 10 mg
   • 10 μg
3. Calculate the moles of phosphine gas produced when each mass of AlP below reacts with excess water in a ship's hull:
   • 10 g
   • 10 kg
   • 10 mg
   • 10 μg
4. Based on your answers to question 3 above, calculate the mass of phosphine produced for each mass of AlP used.
5. Your ship is sailing towards eastern Australia and has just crossed the Tropic of Capricorn. You have been asked to estimate the volume of phosphine gas that will be produced when you release AlP pellets into the ships hold. Which molar gas volume will you use; 22.71 L or 24.79 L ? Explain your answer.
6. Rats are currently infesting a small part of your ship, about 150 m³. How much solid AlP would be required to fumigate this area, but not leave any AlP residue left over?
7. The Cook has already tried to fumigate the pantry and is sure there is a silver canister around that still contains some AlP, it could be in the pile of empty canisters, or, it could be in the pile of full canisters. No-one wants to kill themselves by opening the canisters to find out, so can you suggest a method that could be used on board ship to determine how much AlP is present in each canister.
8. Explain why the reaction between aluminium phosphide and water is described as a proton-transfer reaction and not as a redox reaction.
9. Explain why, even though aluminium phosphide and phosphine are toxic, it is considered safe to use these to fumigate silos containing grain which will be eaten by humans.
10. The silver canisters that have washed up on Australian beaches have no labels, presumably these have come off while they were in the ocean. You have been asked to design new labels for the canisters. The labels must include suitable safety and handling information.

Elemental Fun

For this activity you will need a modern Periodic Table
(here's one I prepared earlier at http://www.ausetute.com.au/pertable.html )

This activity is designed to let students have some fun while they use a Periodic Table to extract information about elements (names, symbols, atomic number and atomic weight).

Ask the students a question.
Students use a Periodic Table find the answers.
After doing a few of these, the students will usually start making up their own questions and answers.
They can try out their questions/answers on their fellow students (and you!).

Names from Symbols

1. Question: What is candy made of?
    Answer: calcium, nitrogen and dysprosium (Ca N Dy )

2. Question: What ingredients do you need to make chocolate?
    Answer: carbon, holmium, cobalt, lanthanum, tellurium (C Ho Co La Te)

3. Question: What elements make up a body?
    Answer: boron, oxygen, dysprosium (B O Dy)

4. Question: What makes up the atmosphere?
     Answer: astatine, molybdenum, sulfur, phosphorus, helium, rhenium (At Mo S P He Re)

5. Question: Prove that these elements are compounds!

• xenon (It's made up of xenon, nobelium nitrogen, Xe No N)
• neon (It's made up of neon, oxygen, nitrogen, Ne O N)
• iron (It's made up of iridium, oxygen, nitrogen, Ir O N)
• copper (It's made up of cobalt, phosphorus (twice), erbium, Co P P Er)
• silver (It's made up of sulfur, iodine, livermorium, erbium, S I Lv Er)
• arsenic (It's made up of argon, selenium, nitrogen, iodine, carbon, Ar Se N I C)

6. Question: What is the most negative element?

    Answer: nobelium, it always spells No

Symbols from Names

1. Question: What fruit is made up of 1 part barium and two parts sodium?

    Answer: Ba Na Na

2. Question: Can you use potassium, nickel and iron to cut an apple?

    Answer: Yes because they make a K Ni Fe

3. Question: If you add some fluorine, uranium and nitrogen to a game, what will happen?

    Answer: It will be more F U N !

4. Question:  What natural fiber is made up of lithium, neon and nitrogen?

    Answer: Li Ne N 

5. Question: What sort of jokes do chemists make out of cobalt, radon, and yttrium?

   Answer: Co Rn Y jokes.

Symbols from Atomic Numbers (crack the code)

1. Code: 1,18,15 

    Clue: A heavenly musical instrument?

    Answer: harp, H (Z=1), Ar ( Z=18), P (Z=15)

2. Code:  66, 7, 95, 53, 52

    Clue: Explosive stuff!

    Answer: dynamite, Dy(Z=66), N(Z=7), Am(Z=95), I(Z=53), Te(Z=52)

3. Code: 20, 28, 10

    Clue: What a cat is afraid of?

    Answer: canine, Ca(Z=20), Ni(Z=28), Ne(Z=10)

4. Code: 1, 85

    Clue: Head covering?

    Answer: hat, H(Z=1), At(Z=85)

5. Code: 67, 8, 19

    Clue: Somewhere to hang your coat?

    Answer: hook, Ho(Z=67), O(Z=8), K(Z=19)

Molecular Weight from Symbols

1. Question: What is a Chemist's favourite number?

    Answer: 315.02 because it is Lu C K Y (175 + 12.01 + 39.1 + 88.91 = 315.02)

2. Question: What is the molecular weight of a gene?

    Answer: 92.82 because it's made up of Ge and Ne (72.64 + 20.18 = 92.82)

3. Question: What is the value of life?

    Answer: 62.791 Li Fe (6.941 + 55.85 = 62.791)

4. Question: What does a boy weigh?

    Answer: 115.72 B O Y (10.81 + 16.00 + 88.91 = 115.72)

5. Question: How heavy is a phone?

    Answer: 68.158 P H O Ne (30.97 + 1.008 + 16.00 + 20.18 = 68.158)

Words You Can Make Using the First Twenty Elements Only

• Al O Ne
• Ar C
• Ar K
• B Ar
• B Ar K
• B Ar N
• Be Ar
• B Li N K
• B Li S S
• B O Ar
• B O Ne
• B O O K
• B O S S
• Ca B
• C Al F
• Ca N
• Ca N Al
• Ca Ne
• Ca N O N
• Ca P
• C Ar
• C Ar B O N
• Ca S H
• C H O O K
• C H O P
• C Li C K
• C Li F F
• C Li N K
• Cl O C K
• Cl O Ne
• C O B
• C O Ne
• C O O K
• C O S H
• F Ar
• F Li C K
• F Li P
• F O Al
• H Al F
• H Al O
• H Ar K
• H Ar P
• He Al
• He Ar
• H O C K
• H O N K
• H O P
• K Na C K
• K N O B
• K N O C K
• Li Ar
• Li C K
• Li Ne
• Li N K
• Li P S
• Li S P
• Na B
• Na P
• Ne O N
• Ne P Al
• N O O K
• O Ne
• O P Al
• P Al
• P Ar
• P Ar K
• P H O Ne
• P O P
• S Ca N
• S C O Ne
• S He
• S He Ar
• Si C K
• Si N
• Si N K
• S Li C K
• S Li P
• S Na C K
• S Na P
• S O B
• S O C K
• S O N Ar
• S P O O K

Uranium Glass

Uranium compounds have been used to colour glass since ancient times. A mosaic found in a Roman villa dated to about 79 AD used yellow glass containing 1% uranium oxide. Between 1880 and the 1920s, uranium glass was quite popular, not only because of its interesting yellow-green colour, but because it fluoresces in ultra-violet light as shown in the image of a vase below.
The image on the left hand side shows the vase under normal daylight, while the image on the right shows the same vase in the dark exposed to UV light.

Why does uranium glass glow green in the dark like this?
Well, it has nothing to do with the radioactivity of uranium isotopes. The green glow does not occur because of changes within the nucleus of uranium atoms, it occurs because of changes in the energy of electrons surrounding the nucleus.
A ground state electron in a uranium atom absorbs the energy of a photon  of ultra-violet light causing the electron to jump to a higher energy level known as the excited state. This new excited state electron configuration is not stable, so, the electron falls back down to to the ground state energy level, which is a lower energy state, by losing energy which it does by emitting a photon of light. Some of the energy of the original photon used to excite an electron is dispersed as molecular vibration and heat, so the energy of the photon emitted when the excited electron falls back to the ground state is less than the energy originally absorbed.
That is: E = hν/λ
where E = energy, h = Planck's constant, ν = speed of light , λ = wavelength of light
If the speed of light is a constant, then E ∝ 1/λ or Eλ = a constant
in other words, the more energy the photon of light has the shorter its wavelength is.
In the case of uranium glass, the absorbed photon of ultra-violet light has a wavelength of about 300 nm, while the emitted photon of green light has a wavelength of about 550 nm.
The wavelength of the emitted photon of light corresponds to the green part of the visible spectrum.
The emission of visible light in this way is known as fluorescence.

Further Reading:
Isotopes
Radioactivity: Properties and Uses
Emission Spectra
Flame Tests

Suggested Study Questions

1. Uranium is found in nature as one of three isotopes, uranium-234, uranium-235 and uranium-238. Explain how atoms of each isotope are:
• the same
• different
2. Atoms of neptunium-234, neptunium-235 and neptunium-238 have been synthesized. Explain the similarities and differences between each of the following pairs of atoms:
   • neptunium-234 and uranium-234
   • neptunium-235 and uranium-235
   • neptunium-238 and uranium-238
3. The value for Planck's constant is 6.626 070 040 x 10^-34 J s and the speed of light is given as 300 000 000 m / s. Calculate the energy of each of the following photons of light:
• ultra-violet light, λ = 300 nm
• green light, λ = 550 nm
4. Using the results of question 3, compare the energy of the photons used to excite uranium atoms and the energy of the photons emitted by uranium atoms and explain the difference.
5. Explain why the same wavelength of light is always emitted when these uranium atoms are exposed to ultra-violet light.
6. Would you expect the uranium glass to fluoresce if it is exposed to infra-red light rather than to ultra-violet light? Explain your answer.
7. Optical brighteners are often used in laundry detergents to make your old, yellowy-looking white clothes look whiter. Typically these compounds absorb ultra-violet light with a wavelength of around 300 nm and emit light with a wavelength of around 450 nm.
   • What colour is the light emitted?
   • What is the energy of the emitted light?
   • Why is the energy of the light emitted not the same as the energy absorbed when the incoming photon hits the "optical brightening compound"?
   • Would you expect a laundry detergent containing "optical brightening compounds" to glow in the dark when exposed to UV light? Explain your answer.

Coral Reef Dissolution

Coral reefs dominate much of the world's tropical coastline, covering about 15% of the seabed shallower than 30 metres.

The largest coral reef in the world is the Great Barrier Reef off the north-east coast of Australia.

What impact will increasing amounts of atmospheric carbon dioxide have on our coral reefs?

Find out in this edition of AUS-e-NEWS!

If you haven't received your copy of AUS-e-NEWS, or if you would like to subscribe to our free quarterly newsletter, AUS-e-NEWS, the email us at

 

Nitrous Oxide Ban

On Saturday 29^th August 2015, Brisbane's Couriermail reported that, "Supermarkets have removed nitrous oxide canisters from their shelves because of the alarming trend of people using the gas to get high".
Nitrous oxide, N₂O, commonly known as "laughing gas", is found as an additive in food (E942). It has been used as an aerosol propellant in whipped cream canisters and cooking sprays, and has also been used as an inert gas to displace oxygen from food packages like potato chips to prevent the food from spoiling. The nitrous oxide canisters being removed from supermarket shelves refer to the small canisters used to re-charge re-usable whipped cream dispensers. Nitrous oxide is soluble in fats and oils so it is pumped into the fatty cream inside the dispenser where it dissolves. When the cream leaves the dispenser, the gas pressure inside the cream is greater than atmospheric pressure, so the nitrous oxide gas leaves the cream quickly, creating a foam. This "whipped cream" has about 4 times the volume of the original cream. However, if the whipped cream is left standing for some minutes, the gas pressure equilibrates with atmospheric pressure and the cream reverts to the "unwhipped" state.
Nitrous oxide has been the preferred choice for whipped cream dispensers because it does not react with the food and prevents it from spoiling. If air were used, the oxygen in the air would accelerate the rate of oxidation causing the cream to spoil. Carbon dioxide gas is not used because it would dissolve in the water present in the cream which would lower the pH and the cream would curdle.

In the laboratory, nitrous oxide can be produced by the thermal decomposition of ammonium nitrate (which is explosive!):

NH₄NO₃(s) → 2H₂O(g) + N₂O(g)

It can also be produced by heating a mixture of sodium nitrate and ammonium sulfate:

2NaNO₃ + (NH₄)₂SO₄ → Na₂SO₄ + 2N₂O + 4H₂O

Nitrous oxide has been used in dentistry as an anaesthetic for more than a century.
The chemistry of how nitrous oxide reacts in the body to produce a "high" is not well understood, but research continues.

Further Reading
Density
Types of Chemical Reactions
Molecular Formula
Name and Formula of Covalent Compounds
Fats and Oils 
Solubility and Le Chatelier's Principle
Mass-mole Calculations
Mass and Moles in Chemical reactions 
Molar Volume of Gases 
Safety in the Laboratory

Suggestion Study Questions:

1. Give the molecular formula for each of the following compounds: 
   • nitric oxide
   • nitrogen dioxide
   • nitrous oxide
   • dintrogen tetroxide
2.  Name each of the following compounds:
   • CO₂
   • CO
   • SO₂
   • SO₃
   • PCl₃
   • PCl₅
3.  Draw possible Lewis (electron dot) structures for each of the following compounds:
   • nitric oxide
   • nitrogen dioxide
   • nitrous oxide
   • dintrogen tetroxide
4.  "..whipped-cream has four times the volume of the original cream", describe what has happened to the density of the cream as a result of the "whipping" process.
5. When I order an "iced-coffee" at a Cafe, they usually top it with some whipped-cream from a canister . Why does the whipped-cream float on top of the ice-coffee drink?
6. If I don't the spoon the whipped-cream off the top of my "iced-coffee" I can stir it into the drink quite easily without it floating to the surface again. Explain why this happens.
7. Explain what is meant by the term "fats and oils" when used by a Chemist and give examples.
8. Most aerosol cans contain a warning to the effect that you should not heat the can. Explain what would happen if you heated a dispenser of whipped-cream containing nitrous oxide. 
9. Imagine placing 10 grams of ammonium nitrate in a 500 mL sealed steel can, which you then (very irresponsively!) throw onto a bonfire.
• Calculate the moles of ammonium nitrate in the can
• Calculate the moles of nitrous oxide gas produced 
• Calculate the volume of this number of moles of gas at 25^oC
• Predict what will happen to the sealed steel can in the bonfire. 
10. Your company, "Ammo-nite", sells ammonium nitrate to farmers for use as a fertiliser. You have been asked to re-design the 100 g package so that it includes relevant safety precautions.

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.

Tonight's the Night

On Friday 21 August 2015 Mt. Stromlo Observatory will be leading Australia in attempting to break two Guinness World Records - Most People Stargazing at a Single Site (Canberra) and Most People Stargazing Across Multiple Sites in a Country (Australia).
Go to http://www.anu.edu.au/events/mt-stromlo-observatory-world-record-night for more information.

Not in Canberra?
No problems.
There are more than 40 sites registered to take part in the attempt to break the World Record for Most People Stargazing Across Multiple Sites in a Country.
Go to http://rsaa.anu.edu.au/world-record-stargazing to learn more.

Haven't got a telescope? Bring binoculars along instead (they will still count for stargazing!).

UPDATE 23/8/2015
1,869 people braved the cold weather in Canberra to set a new Stargazing record surpassing the previous record of 649 by more than 1,000 people!

A second world record was being attempted for the most people stargazing at multiple sites around Australia, and while estimates of around 10,000 people have been suggested which would beat the previous record of 3,007, we are still waiting for exact numbers and confirmation.

Chemical Equilibrium

To understand chemical equilibrium you need to realise that

1. chemical reactions that are in equilibrium DO NOT go to completion. 
2. "reactants" and "products" are all present at equilibrium
3. the "things" that are in equilibrium are the "reactants" and "products" whose concentrations can be changed (that is, substances that exist in solution).
4. equilibrium is the state in which the rate of the forward reaction (reactants → products) is the same as the reverse reaction (products → reactants

Knowing this, we can then write:

• a mass-action expression (http://www.ausetute.com.au/massaction.html)

And then

• the equilibrium law expression (http://www.ausetute.com.au/equilibriumlaw.html)

Which at equilibrium, results in an expression for the

• equilibrium constant (http://www.ausetute.com.au/equicons.html)

Which can be used to:

• calculate concentration (http://www.ausetute.com.au/ricetable.html)
• determine the extent of a reaction (http://www.ausetute.com.au/kextent.html)
• determine the equilibrium constant for the reverse reaction (http://www.ausetute.com.au/kreverse.html)
• determine whether a chemical reaction is exothermic or endothermic (http://www.ausetute.com.au/ktemperature.html)

HCl as a Primary Standard?

Question: Why is HCl not suitable as a primary standard?
Answer:  There are three main reasons why HCl is not suitable as a primary standard:

• HCl is not a solid at room temperature and pressure. 
• HCl cannot be obtained at a very high purity.
• HCl does not have a high molecular mass.

You can find out more about what makes, and does not make, a primary standard at:
http://www.ausetute.com.au/titrstand.html

Which Element has the Smallest Atomic Radius?

Question: Write the symbol for the element which has the smallest atomic radius Na, Si, Mg, P.

Answer: In general, atomic radius decreases going across a period of the Periodic Table.
Sodium (Na), magnesium (Mg), silicon (Si) and phosphorus (P) all belong to the third period.
In order of increasing atomic number they are: Na (Z=11), Mg (Z=12), Si (Z=14), P(Z=15)
Therefore, in order of decreasing atomic radius they are: Na > Mg > Si > P
So, phosphorus, symbol P, has the smallest atomic radius.

Read more about trends in atomic radius at AUS-e-TUTE: http://www.ausetute.com.au/trendar.html

Number of elements in period 2

Question: Give the number of elements in period 2 of the periodic table
Answer: 8

The rows going from left to right across the Periodic Table are called Periods.
The periods are numbered from 1 at the top to 7 on the bottom.
The first period contains only 2 elements: hydrogen and helium.
The second period contains 8 elements: lithium, beryllium, boron, carbon, nitrogen, oxygen,  fluorine and neon.

Find out more about how the periodic table is arranged at http://www.ausetute.com.au/pertable.html

Find more about the elements making up Period 2 at http://www.ausetute.com.au/trendpd2.html

I.C.E., R.I.C.E and Equilibrium

Need to calculate an equilibrium constant, but, you haven't been given all the equilibrium concentrations?
Then you need an I.C.E. Table (also known as a R.I.C.E. Table, an ICE chart, a RICE chart), and you can find out all about that at AUS-e-TUTE's new tutorial:
http://www.ausetute.com.au/ricetable.html

Now, if you are an AUS-e-TUTE Member, not only can go to the great member's only tutorial, but you can also:

• play the R.I.C.E. game
• answer the R.I.C.E. test questions and get immediate feedback
• do the R.I.C.E. exam
• make a R.I.C.E. worksheet (if you are a Teacher Member)
• do a R.I.C.E. quiz (if you a student with a Class or School Group)

And if you still haven't joined AUS-e-TUTE, you can sign up right here !

How many molecules are present?

Question: How many molecules are present in 4.21 mol of hydrogen gas?

Answer: 1 mole of anything contains 6.02 x 10²³ particles.
(Note that "mol" is the abbreviation for mole.)
So, 4.21 mol of hydrogen gas contains 4.21 x 6.02 x 10²³ = 2.53 x 10²⁴ molecules of hydrogen.

You can find a tutorial with worked examples at http://www.ausetute.com.au/namole.html

Which of the following is an acid-base indicator?

Question: Which of the following is an acid-base indicator?

1. hydrochloric acid 
2. sodium hydroxide 
3. water 
4. phenolphthalein

Answer: Phenolphthalein is an acid-base indicator

1. Hydrochloric acid is an acid
2. Sodium Hydroxide is a base
3. Water is neutral

What is the best indicator for titration?

Question: What is the best indicator for titration?
Answer: That all depends on what you are titrating!

If you doing an acid-base titration, then you will need to know the relative strengths of the acid and base you going to be using.
Once you have determined an approximate pH for the equivalence point of the neutralisation reaction, you use this as the pH of the endpoint of the titration in order to determine the best acid-base indicator to use.