Chemistry of Tooth Decay and Prevention

Tooth decay is a major health concern.

For more than 50 years we have been adding fluoride to our water supplies and toothpaste to help prevent tooth decay.

It is estimated that this fluoridation of drinking water alone has resulted in a 25% decrease of tooth decay in children and adults.

What causes tooth decay and how does fluoride prevent tooth decay and cavities?

 Learn about the chemistry of tooth decay and how to prevent it in the March 2021 issue of AUS-e-NEWS. Subscribe to AUS-e-NEWS for free at https://www.ausetute.com.au/ausenews.html

pH After Mixing Weak Acids

 Acetic acid is a weak acid (K_a = 1.8×10^-5).  The pH of 100 mL of 0.10 mol L^-1 acetic acid is 2.9.

Hydrocyanic acid is a weak acid (K_a=6.3×10^-10). The pH of 100 mL of 0.10 mol L^-1 hydrocyanic acid is 5.1.

But what is the pH of the resultant solution if you mixed these two weak acids together?

AUS-e-TUTE has just added new resources to help you understand how to calculate the pH of solutions after mixing weak acids together. AUS-e-TUTE Members should log-in to access the new tutorial, game and test with worked solutions.

If you are not yet an AUS-e-TUTE member, you can access the "free-to-view" tutorial at https://www.ausetute.com.au/phmixwa.html

What is an indicator?

What is an acid-base indicator?

What does it do?

Where do we use acid-base indicators?

These and other questions about acid-base indicators can be answered at 

https://www.ausetute.com.au/indicators.html

AUS-e-TUTE Members also have access to the game, test and exam with worked solutions on this topic.

Join AUS-e-TUTE Today!

What's Wrong with Science Education?

 What's wrong with science education (in Australian high schools)?

Possibly the opinion of those teaching it if this comment by Margaret Shepherd, the president of the Science Teachers Association, is any indication of the thoughts of Australian Science Teachers in general. She said,

“Good scientists require persistence, resilience, being able to do something for a long time without results.”

Persistence ✌

Resilience ✌

 Being able to do something for a long time without results?

Really? You think that's what makes a good scientist?

Rather a dispiriting opinion of the work of scientists isn't it?  Hardly going to make students leap at the chance of a life dedicated to science if all they're going to achieve is a lifetime of waiting for something to happen.

Is it possible to do "something" in science, and achieve no results ... at all ... nothing .... neither supporting nor refuting a hypothesis?

Go read the article: https://www.smh.com.au/national/nsw/why-physics-and-chemistry-are-delivering-more-band-6-hsc-results-20201215-p56nkc.html 

Stay calm .... if you can!

Quick Quiz: Names and Symbols of the Elements

 How well do you know the names and symbols of the first 20 elements...

  Take this Quiz

Recovering Gold from e-Waste

 We use electronic devices every day; computers, drones, home security systems, mobile phones, smart speakers, smart watches, etc. If the device stops working, or we want to upgrade to a newer version, we throw away the old device resulting in electronic waste or e-waste. Each of these devices contains a printed circuit board (PCB) and the metal content of each PCB can be as high as 40% by mass. 

Recycling 1 tonne of mobile phones alone could produce more than 130 kg metal, including about 340 g of gold. The value of just the gold in that tonne of rubbish is over $25,000(AUD). Recovering metal from waste electronics and electrical equipment is becoming big business, but what impact does this have on us and our environment?

 Read this edition of AUS-e-NEWS to find out more ...

You can subscribe to AUS-e-NEWS, AUS-e-TUTE's free quarterly newsletter for chemistry students and teachers, at 

https://www.ausetute.com.au/ausenews.html

Arrhenius Acids and Bases

What is an acid?

What is a base?

These are both good questions and there is no simple answer.

It all depends on how you decide to define the terms "acid" and "base".

More than 100 years ago, a clever chemist by the name of Arrhenius proposed the first really useful definitions of acids and bases and AUS-e-TUTE has just added a new tutorial, game, test and exam (with worked solutions!), and even some flash cards o help you understand and apply the Arrhenius definition of an acid and of a base.

Not an AUS-e-TUTE Member? You can go to a free-to-view tutorial at 

https://www.ausetute.com.au/arrheniusab.html