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2008 WAEC Chemistry Practical (a) In the laboratory preparation of crystals of CuSO\(_4\), a green powder Q was added...

Chemistry
WAEC 2008

(a) In the laboratory preparation of crystals of CuSO\(_4\), a green powder Q was added to dilute H\(_2\)SO\(_4\), and stirred. Effervescence occurred and a gas R was given off which turned lime water milky. Excess Q was removed from the mixture. The solution of Cu\(_2\)SO\(_4\) was concentrated to half its original volume and allowed to stand.

(i) What is substance Q?

(ii) Name gas R

(ii) Why was excess Q used?

(iv) How would you know that the reaction is complete?

(v) What method was used to remove excess Q? (vi) Why was the solution of CusO\(_4\) not heated to dryness?

(b) Name the reagent(s) used for testing each of the following substances in the laboratory: (i) Water; (i) Primary alkanol. 

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Explanation

(a)(i) Q is copper (II) trioxocarbonate (IV) 

(ii) R is carbon (IV) oxide

(iii) Excess Q was used to ensure that all the acid reacted 

(iv) When there is no more effervescence.

(v) Filtration.

 

(b)(i) White anhydrous copper (II) teraoxosulphate (VI).

(ii) Alkaline iodine solution, or acidified potassium tetraoxomanganate (VIl).

 

 


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WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
WAEC offline past questions - with all answers and explanations in one app - Download for free
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WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts