Friday, June 30, 2017

Chiral Centres and Chiral Molecules

What is a chiral molecule?
How do you find the chiral centre, or chiral carbon, in an organic molecule?
What makes a molecule chiral?
Why is chirality important?

These are all excellent questions, and AUS-e-TUTE has just uploaded some excellent resources to help you answer these questions and apply the concepts.

AUS-e-TUTE Members should log-in to use the new resources (tutorial, game and test with worked solutions).
If you are not an AUS-e-TUTE there is a "free-to-view" tutorial currently available for evaluation purposes at http://www.ausetute.com.au/chirality.html

Saturday, June 10, 2017

Airbags



"BANG! I hit a hard pillow! Then there's white powder everywhere!", Sam graphically described a recent car accident.
The hard pillow is the inflated airbag, a safety device incorporated into cars which is designed to reduce the risk of serious injury during a collision, as it did in this case.

Where does the air in the airbag come from? And what is all that white powder?

Read all about the chemistry of airbags in the June 2017 edition of AUS-e-NEWS.

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Sunday, May 14, 2017

Oxygen Gas From Comets

Rosetta was a European Space Agency (ESA) Mission, launched in 2004 with the goal of capturing comet 67P/Churyumov-Gerasimenko in 2014 and to accompany it into the interior solar system. Onboard was an instrument known as ROSINA (Rosetta Orbiter Sensor for Ion and Neutral Analysis) which combined two mass mass spectrometers to study the composition of  the comet's corona.
In 2015, researchers from the Center for Space and Habitability (CSH) at the University of Bern analysed the comet's gases and made an unexpected discovery, traces of molecular oxygen (O2(g)) were detected! It turned out that molecular oxygen was the fourth most abundant gas in the comet's atmosphere after water, carbon monoxide and carbon dioxide!
Where did this molecular oxygen come from? Surely if it was formed very early, at about the same time as the Solar System, it would have reacted with other substances by now because molecular oxygen is very reactive. We could expect compounds containing oxygen like carbon dioxide and water, but not molecular oxygen.
This puzzle was only solved in 2017.

Caltech Professor Konstantinos P. Giapis studies chemical reactions involving high-speed ions colliding with semiconductor surfaces as a means to create faster computer chips and larger digital memories for computers and phones. He thought the same thing was happening in the comet.

First, as the comet is heated by the sun, water vapor is released from the icy comet..
Next, ultraviolet light from the sun causes the water molecules to become ionised.
Then the ionized water molecules are pushed back towards the surface of the comet by the sun's wind.
After that the ionized water molecules hit oxygen containing compounds on the surface of the comet like rust and sand.
Finally the molecules pick up another oxygen atom from these surfaces to form molecular oxygen.

This gives us a possible mechanism by which molecular oxygen could be produced in space without the need for living things, and, could change the way we search for signs of life on planets beyond our solar system.


Reference
California Institute of Technology. "Chemical engineer explains oxygen mystery on comets." ScienceDaily. ScienceDaily, 8 May 2017. .

Further Reading:
Pure Substances and Mixtures

Elements and Compounds

Molecular Formula

Molecular Formula for Covalent Compounds

Physical and Chemical Changes

Mass and Moles in a Chemical Reaction

Mass Spectroscopy for Isotopes

Mass Spectroscopy for Structural Determination


Suggested study Questions:
  1.  Which of the following are pure substances?
    • molecular oxygen
    • water
    • carbon monoxide
    • carbon dioxide
    • rust
  2.  Which of the following substances are mixtures?
    • molecular oxygen
    • water
    • carbon monoxide
    • carbon dioxide
    • rust
  3. Which of the following substances are elements?
    • molecular oxygen
    • water
    • carbon monoxide
    • carbon dioxide
    • rust
  4. Which of the following substances are compounds?
    • molecular oxygen
    • water
    • carbon monoxide
    • carbon dioxide
    • rust
  5.  Write the molecular formula for each of the following:
    • molecular oxygen
    • water
    • carbon monoxide
    • carbon dioxide
  6.  Write chemical equation for the first reaction that occurs on the comet's surface.
  7.  Explain how a water molecule could be ionized.
  8.  Explain why molecular oxygen is considered to be a reactive molecule. 
  9.  Assume that a comet has a mass of 1014 kg and that it is composed only of water. Calculate the maximum mass of molecular oxygen that could be formed if the entire comet was vaporized.
  10.  Explain how a mass spectrometer can be used to identify elements and compounds in space.
  

Sunday, April 30, 2017

What makes a good fuel?

There are lots of fuels to choose from.
Some are non-renewable fossil fuels such as oil, kerosene, petrol or gasoline, diesel or petrodiesel, coal, natural gas, coal seam gas (CGS).
Some are renewable biofuels like biodiesel, bioethanol, biogas.
How can chemistry help us decide which fuel to use?
I'm glad you asked!
AUS-e-TUTE has just added new resources (tutorial, game, test, exam, drill) to help you understand how a fuel is chosen for a purpose.
AUS-e-TUTE Members should log-in to use the new resources.
If you are not an AUS-e-TUTE, you can now access a "free-to-view" Comparing Fuels tutorial at http://www.ausetute.com.au/fuelenergy.html

Saturday, April 8, 2017

Mass Number and Number of Neutrons

What is the mass number of an atom?
Why is it called a "mass number"?
How many nucleons are in an atom of an element?
How many neutrons will you find in the nucleus of an atom?

These are all good questions, which is why AUS-e-TUTE has just added new resources to help you understand and answer these questions.
AUS-e-TUTE members should log-in to access the new tutorial, game, test and drill.

Not an AUS-e-TUTE Member?
A "free-to-view" mass number tutorial with worked examples is currently available at
http://www.ausetute.com.au/massnumber.html

If you want to play the games, do the tests, exams and drills and get immediate feedback on your answers, you will need to join AUS-e-TUTE.

Saturday, March 18, 2017

How Many Electrons in an Atom?

For an atom of an element:
number of electrons = number of protons = atomic number of element

AUS-e-TUTE has a new tutorial, game, test and drill to help you learn and apply this idea.
AUS-e-TUTE members should log-in to access these new resources.

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

Saturday, March 11, 2017

How Many Protons in an Atom?

number of protons in an atom = atomic number (Z) of the element

... and.... the periodic table of the elements lists the elements in or order of increasing atomic number!

Now, if you'd like to see AUS-e-TUTE's new tutorial on this topic, along with worked examples of exam questions, you will need to visit http://www.ausetute.com.au/noprotons.html

But, if you would like to play the game, answer the test questions, or do the drill, then you will need to become an AUS-e-TUTE Member at http://www.ausetute.com.au/register.html