[S$399.00](▼21%)[Special Promotions]ECOVACS DEEBOT OZMO Slim11 / OZMO™Mopping Technology / App Control / Google Home Support

WWW.QOO10.SG

Saturday, 31 March 2018

Organic Chemistry App - Alkanes, Alkenes, Alcohols and Carboxylic acids

Want to know how well you know the organic chemistry chapter?

To test your basic knowledge on these homologous series (i.e. alkanes, alkenes, alcohols and carboxylic acids), I have created two new Apps available for download at Google Play:

Each App consists of a number of questions, with answers. In each question, there is a short description, and one is supposed to determine the homologous series which best fits the description. Going through these questions, will reinforce the key concepts tested in the O level Organic Chemistry.

We usually have some small pockets of time available. And many of us make use of them by "looking" at our smart phones. What do you usually do when you "look" at your smart phone? I have a suggestion. Why not revise some topics that you have learnt? I have created a number of Apps which can allow you to revise small parts of your Chemistry syllabus quickly. You can find them here

Friday, 30 March 2018

Electrolysis - What's at the anode and cathode?

The content part for the electrolysis chapter is relatively short. You can learn in detail here. It is the application of theory to questions that is more important here. There is not much to memorise.

Instead of creating flash cards with content for this chapter, the first App for electrolysis is one which has a number of questions. This is because questions for this chapter are rarely those that require you to regurgitate. Rather, they are more of the application type. This App gives you application questions on finding what is formed at the cathode and anode for a given electrolyte.

If you would like to learn electrolysis on the GO, by looking at example questions, download the Electrolysis App, now available at google play store here.


Related Posts

Friday, 16 March 2018

Chemistry App - How to find number of electrons in particles

I would like to share a new app now available on Google Play store, available for download for free here.

https://play.google.com/store/apps/details?id=com.chemistryforsg.FindNumberofElectrons&hl=en


This App teaches both how to find the number of electrons in particles (e.g. atoms, cations or anions). To reinforce what you have learnt in the short notes in this app, there is also a quiz.

Learning how to find the number of electrons is particularly important for the chapter on chemical bonding, such as finding the electronic configuration.

Related Posts




Thursday, 15 March 2018

Hydrogen Peroxide Disproportionation - Video Sharing

In the notes on redox, we mention that hydrogen peroxide can be oxidized or reduced, depending on what other chemical is added to it.

When hydrogen peroxide is oxidized, it is converted to oxygen.

When hydrogen peroxide is reduced, it is converted to water.

Hydrogen peroxide can also undergo disproportionation, which means it is oxidized and reduced simultaneously. Water and oxygen is formed when this reaction takes place, as illustrated in the equations below:

hydrogen peroxide --> water + oxygen

2H2O2 ---> 2H2O + O2

The following is a cute video showing the disproportionation of hydrogen peroxide:


Wednesday, 14 March 2018

Mole Concept App

I mentioned in the previous post that I will be creating flashcards which can be downloaded on Google Play. In this post, I would like to share with you the mole concept App which I have created. This App is available at Google PlayClick here to download. If you like the App, please leave a positive comment for it.

In this App, you have find both mole concept flashcards, as well as questions to reinforce what you have learnt. The questions include finding number of moles, mass of compounds, volume of gases, concentration of solutions, and so on. Answers are provided in the app.

I will be posting full work solution on this website soon. Stay tuned!

Related Post:
Mole Concept, Learning from Example 
Mole concept formulae

Question:
Quizzes and Tests on Mole Concept



Monday, 12 March 2018

Mole Concept - A simple way to manipulate these equations

I was tutoring one of my students, and I realized she wasn't good at algebraic equation manipulation. She memorized the mole concept equations religiously. However, when the question requires her to do some manipulation to the equations she memorized, she struggles. While I told her the main solution to this problem is to improve her algebraic manipulation, I still came up with a simple solution to this, while she worked on improving her algebraic manipulation.

Triangle Method

The triangle method can be used when you have one of the following equations:
(1) A = b x c
(2) b = A / c

When given either of the above equation, put A at the top of the triangle and b and c at the bottom of the triangle.


To find any of the variables at the bottom of the triangle, take the top divide by the either variable at the bottom of the triangle.

Hence you have (1) b = A / c  (2) c = A/ b
You will notice that the way the triangle is written, it looks like A/c or A/b, hence a way to memorize the above.

To find any of the variables at the top of the triangle, multiple the two variables at the bottom of the triangle together, i.e. A = b x c

Application of the Triangle Method to Mole Concept

Equation 1: Mole = Mass/ molar mass


You'll put Mass at the top of the triangle, and mole and molar mass at the bottom.
The three equations you'll get out of this is
mass = molar mass x moles
molar mass = mass / moles
moles = mass / molar mass

Equation 2: Mole = Volume / Molar volume


You will put volume at the top of the triangle, and molar volume and moles at the bottom of the triangle:

Note that this equation is only applicable for gases, and volume and molar volume must be in the same units. Example, if volume is in dm3, then molar volume must be in dm3.

Example 3: Concentration (g / dm3) = mass  (in g)/ volume (in dm3)


You will put mass at the top of the triangle, and concentration and volume at the bottom of the triangle.

With that, you three equations you will get will be:
mass (g) = concentration (g/dm3) x volume (dm3)
concentration (g/ dm3) = mass (g) / volume (dm3)
volume (dm3) = mass (g)/ concentration (dm3)
Note that this equation can only be used for solutions (generally aqueous solutions for the O level syllabus).


Example 4: Concentration (mol / dm3) = moles/ volume (in dm3)


You will put moles at the top of the triangle, and concentration and volume at the bottom of the triangle.

With that, you three equations you will get will be:
moles = concentration (mol/dm3) x volume (dm3)
concentration (mol/ dm3) = moles / volume (dm3)
volume (dm3) = moles/ concentration (dm3)

Note that this equation can only be used for solutions (generally aqueous solutions for the O level syllabus).


Example 5: Conversion between concentration in g/dm3 and mol/dm3

concentration (mol/dm3) = concentration (g/dm3) / molar mass

You will put concentration (g/dm3) at the top of the triangle, and concentration (mol/dm3) and volume (dm3) at the bottom of the triangle:

concentration (g/dm3)  = concentration (mol/dm3) x molar mass
concentration (mol/ dm3) = concentration (g/dm3) /molar mass
molar mass =  concentration (g/dm3) /concentration (mol/ dm3)

Note that this equation can only be used for solutions (generally aqueous solutions for the O level syllabus).


Equation 6: Moles = Number of particles / Avogadro Constant


In this case, you will put number of particles at the top of the trianges. Moles and Avogadro Constant go to the bottom of the triangle.

With that, the three equations you get are:
number of particles = Avogadro's constant  x moles
Avogadro constant = number of particles/ moles
Moles = Number of particles / Avogadro constant.


Tuesday, 6 March 2018

Global Warming - Video sharing

In the notes on air and atmosphere, we talked about greenhouse gases and global warming.

Gases such as carbon dioxide and methane are greenhouse gases. These gases trap heat, and keep the earth warm at night when the sun sets. Excessive amount of these gases, however, causes climate temperatures to rise, also known as global warming.

We learn about the side effects of global warming, e.g. melting of ice caps, and potentially flooding low lying areas when massive amount of them melt.

Watch the video below from National Geographic to find out more about causes and effects of global warming.




Related Post
Air and Atmosphere

Questions
Quizzes and Tests on Air and Atmosphere


Popular Posts