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.
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
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Unknown Reply:
July 31st, 2009 at 4:47 pm
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
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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..
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Ans: Pipette. There is 125cm3 pipette to transfer the acid (analyte, etc) into the beaker for acid-base titration.
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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.
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Question 1:Fuels are associated with some ammount of Nitrogen in combination with sulfides.So on combustion it will give rise to oxides of Nitrigen and sulfur when it undergoes cobustion into carbon dioxide and methane..Also
PAHs I.e poly aromatic hydrocarbons.
Ans 2: Wet litmus paper can be used to test water-soluble gases; the gas dissolves in the water and the resulting solution colors the litmus paper. For instance, ammonia gas, which is alkaline, colors the red litmus paper blue.
ANS 3:Pipette is used 4 transfer of small volumes.In this case Burette can be used because if we use pipette then 3 times we have 2 do tranferring.IT WILL INCLUDE ERROR..ALWAYS SHOULD FOLLOW A PATH WHICH WILL HAVE LESS NO. OF STEPS.
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hmmmmmmmmmm………………nice…….itz mostly sove my proble
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