O Level Chemistry Questions: Experimental Techniques / Purification & Separation


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.

Related Articles:

Many people talked about teaching Chemistry, I simply LOVE it. I am a passionate Chemistry Coach based in Singapore, Southeast-Asia and aspire to be one of the most dynamic, powerful and humorous speakers in Asia. My 16+ years of coaching experience has equipped me to understand the true reasons why students are not able to perform well in Chemistry, and allow me to structure my teaching methodology to cater to different levels of learners. If you have found this post useful, please share it with your friends. I would really appreciate it! Sean Chua

6 Responses to O Level Chemistry Questions: Experimental Techniques / Purification & Separation
  1. Anonymous
    September 12, 2007 | 7:20 am

    Answer for question3 is pipette. Cos pipette measures 25cm3 of liquid.
    So if you want to measure 125 cm3, just do it 3 times using a pipette! =)

    And the rest of the answers are correct! yay.hahaha

    Reply

    Unknown Reply:

    basically.. it’s doing it 5 times instead of three .. and a burette is a much more accurate apparatus as compared to the pipette. The 25cm3 may be a little vague, resulting in a higher probability of having experimental errors :)

    Reply

  2. lijun(:
    September 12, 2007 | 7:38 am

    Q3) What apparutus is best used to transfer 125cm3 of acid into a beaker? [1 mark]Ans: Pipette or burrete?

    pipette can only measure up to 25cm3, or at most 50cm3 only. so i don’t think it’s possible to transfer it by pipette..

    Reply

  3. alwaysLovely
    September 14, 2007 | 3:02 am

    Ans: Pipette. There is 125cm3 pipette to transfer the acid (analyte, etc) into the beaker for acid-base titration.

    Reply

  4. zainz
    October 11, 2010 | 10:13 pm

    burette, caz’ thatz more accurate and can even give the reading in points.
    in laboratories, mostly a burette is considered an appropriate instrument for adding acids.

    Reply

  5. mujahid
    June 18, 2014 | 12:05 am

    I want to read and get the papers

    Reply

Leave a Reply

Wanting to leave an <em>phasis on your comment?

Trackback URL http://www.simplechemconcepts.com/chemistry-questions/trackback/