C is an organic compound. Carry out the following... | WAEC SSCE - Chemistry - 2020 (Practical)

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C is an organic compound. Carry out the following exercises on C. Record your observations and identity any gas(es) evolved. State the conclusions you draw from the results of each test.

(a) Put about 10 drops of C on a watch glass and ignite it using a burning splint.

(b)(i) Put about 1 cm\(^3\) of C in a test tube and add about 1 cm\(^3\) of distilled water. Shake the test tube.

(ii) Put about 1 cm\(^3\) of C in a test tube and add about 2 cm\(^3\) of acidified K\(_2\)Cr\(_2\)O\(_7\) solution. Warm the mixture gently and leave to stand for 5 minutes.

(c) Put few crystals of specimen D in a test tube and add about 2cm\(^3\) of C followed by about 2 cm\(^3\) of 10 % NaOH\(_{(aq)}\) Shake the test tube vigorously.

(d) State the class of compounds to which C belongs.

Answer

Test	Observation	Conclusion / inference
(a) C on a watch glass, ignited with a burning splint	C burns readily with a clean, non-sooty blue flame. No solid residue remains.	C is a flammable saturated organic compound. The gaseous products of complete combustion are carbon(IV) oxide, CO₂, and water vapour, H₂O.
(b)(i) C + distilled water; shake	One clear homogeneous layer is formed.	C is miscible with water.
(b)(ii) C + acidified K₂Cr₂O₇(aq); warm gently and allow to stand	The orange dichromate(VI) solution changes to green.	C is oxidised while dichromate(VI) ions are reduced to Cr³⁺. C is a primary or secondary alkanol.
(c) Iodine crystals, D, + C + 10% NaOH(aq); shake vigorously	A pale-yellow precipitate with a characteristic antiseptic smell is formed.	Triiodomethane (iodoform), CHI₃, is formed. C contains the ethanol group, CH₃CH(OH)−, and is ethanol.

Test	Observation	Conclusion / inference
(a) C on a watch glass, ignited with a burning splint	C burns readily with a clean, non-sooty blue flame. No solid residue remains.	C is a flammable saturated organic compound. The gaseous products of complete combustion are carbon(IV) oxide, CO₂, and water vapour, H₂O.
(b)(i) C + distilled water; shake	One clear homogeneous layer is formed.	C is miscible with water.
(b)(ii) C + acidified K₂Cr₂O₇(aq); warm gently and allow to stand	The orange dichromate(VI) solution changes to green.	C is oxidised while dichromate(VI) ions are reduced to Cr³⁺. C is a primary or secondary alkanol.
(c) Iodine crystals, D, + C + 10% NaOH(aq); shake vigorously	A pale-yellow precipitate with a characteristic antiseptic smell is formed.	Triiodomethane (iodoform), CHI₃, is formed. C contains the ethanol group, CH₃CH(OH)−, and is ethanol.

Organic Compounds

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C is an organic compound. Carry out the following exercises on C. Record your observations and identity any gas(es) evolved. State the conclusions you draw ...

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C is an organic compound. Carry out the following exercises on C. Record your observations and identity any gas(es) evolved. State the conclusions you draw ...

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