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 ...
Question 1 Report
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 Details
Results of tests on C
| 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. |
(d) C belongs to the class of alkanols (alcohols). Specifically, C is ethanol, CH3CH2OH.
The combustion of ethanol may be represented by:
\[\mathrm{C_2H_5OH(l)+3O_2(g)\rightarrow 2CO_2(g)+3H_2O(g)}\]
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