Mole Calculations, or commonly known as ?The MOLE? or ?Mole Concepts? is regarded by many of the GCE ‘O’ Level Chemistry students (as well as IGCSE and IB / IP Chemistry students) to be one of the most challenging and difficult topic.
Let’s not mention that many students are not able to score in this topic!
In fact, a large number of chemistry students simply “hate” Mole Calculations, because they:
- Don’t know which formulae to use
- Don’t even know how to start when they read the question
- Can’t relate how mathematical manipulations are connected to chemistry theories
- Can’t handle the fact the Mole Calculations are everywhere & anywhere in Chemistry Exams – they appear in questions that are linked to various other chemistry topics
As such, many students have in fact given up on Mole Calculations! But question is: Can they afford to give them up? Let me know your views on it? Do you think students can afford ignore Mole Calculations?
Even worst, we have received emails from chemistry teachers and chemistry tutors (tuition centre teachers) on the challenges in teaching their students. Many students seemed to “understand” the examples shared by their chemistry teachers during lecture but once the question is rephrased a little bit, students will be stunned and do not know how to carry on. Are you one of them? I would love to hear from you.
Recently, we have seen more students asking us to discuss more about Mole Calculations in this chemistry blogsite. One of my chemistry student, who is committed to do well in the October?s GCE ?O? Levels Chemistry Exams, had sent me a series of questions related to Mole Calculations. And one of them is a challenging application question that i have addressed last year (2009). Let’s check out the question:
Question:
12dm3 of polluted air is passed through limewater so that all the carbon dioxide is precipitated as calcium carbonate. The mass of calcium carbonate formed is 0.05g. What is the percentage by volume, of carbon dioxide in the air sample?
Now, take out your calculator, pen & paper – and try it out! Leave your answer (and even better, leave down your working) in the Comment section below.
I will be providing the solution soon. But before that, i would strongly suggest that you attempt the question first to see if you have the correct answer. =)
Suggested Solution:
Updated on 2nd March 2010:
For full screen video – click HERE
PS: If you are based in Singapore, there is a chance now that you can master Mole Calculations quickly & effectively. Click HERE for more information.
good ques 4 helping students!!:)