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

How to study for Chemistry exams

As your chemistry exam gets closer, I'm sure you've been "studying" hard, probably reading through your notes, making summaries, summarizing the summaries, putting important concepts on flash cards... and a whole lot more. But will any of that help you achieve a good result on a chemistry exam?

Probably not. So, put your notes away and read on.

Chemistry examiners are not interested in whether you have memorized the "facts" (definitions, formulae etc). It is most unlikely that the following question will appear on a chemistry exam paper,

Question 1: "State Le Chatelier's Principle"

Chemistry examiners are interested in how you apply chemical principles to solve problems. So the following question is much more likely to be found on a chemistry exam paper,

Question 2: "A student dissolves some solid FeSCN²⁺ in water in a test tube at room temperature and pressure, producing a mixture of reddish-brown FeSCN²⁺(aq), pale yellow Fe³⁺(aq), and colourless SCN^-(aq). The student observes that the test tube feels cooler as the solute dissolves.

(a) Write an equation to describe the process.

(b) Describe what colour change, if any, would occur if the test tube was placed in an ice-bath. Explain your answer"

Question 2 is asking you to apply Le Chatelier's Principle to a given chemical process.

The best way to study for your chemistry exam is to answer a variety of questions. AUS-e-TUTE Members have access to thousands of problems (with worked solutions and tutorials if you need some help). If you are not an AUS-e-TUTE member you can often find books of problems for a given course, and you probably have access to "past papers". 

Here's another question you might like to try,

Question 3: One step in the Ostwald process for manufacturing nitric acid from ammonia involves the production of nitrogen dioxide as shown in the chemical equation below:

2NO(g) + O₂(g) ⇋ 2NO₂(g)

A 10.00 L reaction vessel initially contained 2.50 mol NO(g) and 1.20 mol O₂(g).

0.50 mol NO(g) remained in the vessel after equilibrium was established.

(a) Calculate the equilibrium constant for this reaction.

(b) A second experiment was conducted using the same initial amounts of NO(g) and O₂(g) but in a reaction vessel of about half the volume. What affect would this have on the value of the equilibrium constant? Explain your answer. 

If you find these questions a bit tricky, then AUS-e-TUTE might help you become more familiar with exam-type questions and how to answer them. Join AUS-e-TUTE today

Brønsted-Lowry Theory of Acids and Bases

 Ammonia, NH₃, is a base right?

Well, yes it is sometimes... but it can also be an acid.

Welcome to the wonderful world of Brønsted-Lowry acids and bases.

At AUS-e-TUTE, we've just added a new tutorial, game, tests and exam to help you understand Brønsted-Lowry acids, bases and their conjugates.

If you are not an AUS-e-TUTE Member you can view a tutorial on this subject for free at https://www.ausetute.com.au/bronstedlowry.html

Emergency Oxygen

Have you ever sat on a plane listening to the flight attendants give the safety demonstration,

"In case of cabin depressurization, oxygen masks will drop automatically..."

and wondered about where, and how, this emergency oxygen is stored?

 Read this edition of AUS-e-NEWS to find out! 

You can subscribe to AUS-e-NEWS at https://www.ausetute.com.au/ausenews.html

Weak Acid - Strong Base Titration Curves

A titration of a weak acid with a strong base results in a titration curve with some notable features, including:

• buffer zone (weak acid in equilibrium with its conjugate base)
• point where pH = PK_a which can be used to determine pK_a, and hence K_a, for the weak acid
• equivalence point where pH > 7 due to the hydrolysis of the anion

Find out more at https://www.ausetute.com.au/titrcurvwasb.html

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

"Summer Science" 2020

The Royal Society (UK) has moved its "Summer Science" program online for 2020.

Good news for everyone ... especially those of us who are not in the UK!

Visit their website for information about the program: https://royalsociety.org/science-events-and-lectures/2020/summer-science-online/