I will be constantly providing some tips to highlight some common mistakes made by students that prevented them in scoring for Chemistry Examinations.
Today, i would like to cover Significant Figures in Mole Calculations for Chemistry. I was coaching several students for last week and noticed that they are not very certain on the use of significant figures when they leave their final answers for Mole Calculations. Many times, we see students having great understanding and strength in Mole Calculations, but they lost valuable marks due to the inaccuracy of the final answers.
–> Significant figures are NOT the same as Decimal places. For example, 127.09 is to two decimal places but to five significant figures. Zeros before any definite numbers do not count as significant figures, so 0.00000048 is to two significant figures.
–> When doing calculations, your final answers to each section should be to the correct number of significant figures. Generally, it should be to the same number of significant figures as the data given in the question. You may get penalized if you write your answers to an excess number of significant figures, e.g. 3.26758 instead of 3.27.
Something Simple yet Important to note.
Hope this will galvanize you to score more full marks in those calculation questions in Chemistry.
Hello once again
Could you tell me how drying agents like quicklime (calcium oxide), concentrated sulphuric acid work?
How do they dry gases?
Looking forward to your sec 4 intensive lessons.
Thank you!
Reply
Hi Jennifer,
A) Drying Agent
Both Quicklime and Conc. Sulphuric acid has strong affinity for water molecules
and thus they are chemically used as drying agents for many compounds. As such,
many are used as a drying agents to dry gases. E.g. remove water vapour content
from air or gas mixtures in the laboratory. Hope this answers your questions. I don’t
O level you have to go too in-depth of the mechanism.
B) Intensive Revision Programs
The March program went well and the students in the class enjoyed themselves whie
learning the ropes for several Sec 3 fundamental topics.
After the Mid-Year Examinations, my intention is to open up two Intensive Revision
Bootcamp for Chemistry.
a) Sec 3 Syllabus Intensive Bootcamp – Sec 3 and 4 students can attend
b) Sec 4 Syllabus Intensive Bootcamp – Sec 4 graduating students to attend
It will be about 3 to 6 hrs kind each day. I am looking into the details now such as
venue, size of class, hrs each day in order to complete revision, etc.
Do stay tuned to the posts in this Chemistry Blogsite as i will be mentioning it.
There will be a closing registration dateline so that i can know the number of students
participating and i can then focus on preparing the quality contents / notes / activities
to benefit the students.
Hope this information helps.
Sean
Reply
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