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/

pH of Aqueous Salt Solutions

If you titrate acetic acid with sodium hydroxide, what is the pH at the equivalence point?

If you dissolve ammonium chloride in water, what is the pH of the solution?

To answer these questions you will have to calculate the pH of an aqueous salt solution!

AUS-e-TUTE has just added new resources to help you do just that!

Members should log-in to use the new tutorial, game, test, drill, worksheet wizard, and problem solving template.

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

pH of a Solution When Weak Acid and Strong Base are Mixed

What happens to the pH of a weak acid as you add strong base to it?

For example, aqueous sodium hydroxide solution (NaOH_(aq)) is a strong base and acetic acid (CH₃COOH_(aq)) is a weak acid.

If you add 10 mL of 0.20 mol/L NaOH_(aq) to 25 mL of 0.10 mol/L CH₃COOH_(aq), what is the pH of the resultant solution?

Find out how to work this out, and work through other examples with worked solutions at AUS-e-TUTE.

A "free-to-view" tutorial is available at https://www.ausetute.com.au/phmixwasb.html

AUS-e-TUTE Members should log-in to play the new game, do the test and get repetitive endless practice with the new drill.