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.