O Level Chemistry Made Easy
Halo all students preparing for your O Level exams,
Do try out the following Chemistry Question from the Top 5 Sec Schools in Singapore during their Preliminary Examinations:
Question:
The number of atoms in 25g of Butane is:
A. 3 X 10^23
B. 3.6 x 10^24
C. 4.2 x 10^23
D. 4.2 x 10^24
Do try and send me your answers, probably by the email or leave a comment below the “COMMENT” section.
All the Best
Sean
Master Trainer =)
Question:Why no complete answers to qns post?
Answers:
1. Learning isn’t about reading answers;they’re about applying your knowledge to solve the questions.
2. We help students only when they take actions, regardless of the size of the action.Sending an email with the queries is an action taken. Sending qns with personal working is another massive action.
3. We believe that most of you will learn best by knowing yourself first. Knowing and recognising your strengths and weakness are important as you acknowledge them.
So if you want answers/solutions for the questions posted, take ACTION by showing us your working and we revert back to you with comments 🙂
No name will be published, we respect your privacy as much as our own.
To Your Academic Success in Chemistry and Math,
Sean Chua
Master Trainer for Chemistry
Ways to increase interest in Chemistry and Improve your grades be it for GCE O Level Chemistry, ICGSE, IB or IP prorgammes.
Everyday Life Occurences is the KEY!
As i have mentioned earlier, learning Chemistry is easy when you show aptitude and interest in the subject. Chemistry is happening around us everyday – all the phenomenons.
Below i would like to share with you on a Chemistry Phenomenon that i came across in TODAY papers dated 25th Aug 07.
Title: Did Pigeon Poo Weaken Fallen Minnesota Bridge?
I almost LOL when i read the title of this article. Interesting isn’t it. Corny in a way. But after catching my breath and reading through – it is no corny anymore, it is based on scientific knowledge.
Inspectors searching for causes of the collapse of a Minnesota Bridge this month that killed at least 13 people have identified pigeon droppings as a possible factor. It is thought the build-up of Guano over many years could have speeded up the rusting of the steel beams in the eight-lane bridge, which collapsed into the Mississipi River on Aug 1.
Structural engineers had been aware of the problem as early as 1987, when inspectors noted a coating of Guano on the inside of some of the steel girders. Pigeon droppings contain Ammonia and Salt, which, when combined with rainwater, can lead to tiny electrochemical reactions that rust the steel.
“Over a long term, it might in fact cause structural weaknesses.” Mr Neal Langerman, of the prestigous American Chemical Society (ACS) said.
The authorities can point to efforts to contain the problem, when screens were put up to prevent pigeons from nesting in some if the openings in the structure. But the build-up of Guano is thought to have continued on the other parts of the bridge.
Guano is just one of the factors that Inspectors are considering as they seek to prevent a repeat of the catastrophe in other ageing bridges in the United States.
Here is what i call CHEMISTRY – The World of Wonders!
Enjoy,
Sean, Master Trainer
Chemistry Made Easy
On 9/8/07, student wrote:
i have alot of difficulties understanding this two subject..Physics & Chemistry
is dere any easier way to rmb the points?
Hi student,
Learning subjects are like playing games, you need to know the rules of the games in order to play them well with good strategies certainly.
Physics:
– Know definition well
– Know the formulae
– Know about Units conversion
Units conversion will help rmbr Formulae, and in turn, help to rmbr most of the definitions.
This is a skill that some school teachers have ceased to impart.
Chemistry:
– Most Interesting of all 3 Sciences.
– Dont really have to memorise much (except QA for O Level). Rest are just based on simple concepts, and observations in life. Let’s just open our minds and eyes.
– Do not skip simple chapters, bcos they will be the strings to tie up all the “more difficult” chapters. They are impt.
– Need to link them to everyday life. Indeed Chemistry is everywhere around us, if you are aware of it.
Hope this helps. Let me know if you need further assistance.
Sincerely,
Sean Chua
Master Trainer
Chemistry Made Easy
Interesting question sent in by another student:
From the scan in the attachment,- How do you answer question 20? How do you know how the different indicators will behave when they are mixed together?-
What’s the correct answer for Q21 and Q22.
Some potassium carbonate solution is added to a sample of tap water. The mixture then appears cloudy. Which of the following ions is probably present in the sample?
A) Bromide ions
B) Magnesium ions
C) Ammonium ions
D) Sulphate ions
Yea, I have no clue how to do this question
What is observed when hydrogen sulphide gas is reacted with iron(III) chloride solution?
What happens when iron is heated with sodium oxide?* Hmm, for this question, isn’t there like no reaction. Cause iron is less reactive than sodium right, so it won’t displace sodium & won’t react? Evidently I’m wrong cause it’s a 5 mark question though. How?
I cant seems to understand Chemistry even i have attended Chemistry Tuition as well as having Chemistry Tutor. It was recommended by a relative, but does not work at all.
This is a question sent in by a student doing GCE O Level Chemistry Examination:
Hi. need some help for the following questions.
Q1) What other gases is present inside a chimney besides dust, sulphur dioxide and carbon dioxide? [2 marks]Ans: carbon monoxide, oxides of nitrogen. CORRECT?
Q2) Why must a litmus paper be moist when testing for gases? [1 mark]Ans: So that the gas can dissolve in water to form its H+ or OH- ions that determines its acidic/alkaline property. CORRECT?
Q3) What apparutus is best used to transfer 125cm3 of acid into a beaker? [1 mark]Ans: Pipette or burrete?
Q4) Why can’t a solution of copper (ii) oxide crystal be heated? Why must it be left evaporating and not heating? [1 mark]Ans: Because the crystals upon heating will decompose. CORRECT?
PS: Let’s us discuss on those questions above. You can leave your answers and suggested solutions in the “COMMENTS” section below.