Carry out the following exercises on sample C. Record your observations and identify any gases evolved. State the conclusion you draw from the result of each test.
(a) Put about half of sample C into a conical flask and add about 5cm\(^3\) of tetrachloroethane followed by 15cm\(^3\) of water. Shake vigorously for about one minute. Put the resulting mixture into a burette and allow to stand until two layers separate. Run the two layers into two separate conical flasks and label them accordingly.
(b) Using the following reagents only, bench sodium hydroxide solution, aqueous ammonia solution, aqueous lead (II) trioxonite (V) solution, silver trioxonitrate (V) solution. bench trioxonitrate (V) acid. Identify the ions present in the upper layer solution
(c) Add 2 – 3 drops of the lower layer solution to about 2cm\(^3\) of starch solution from your result, name the substances which dissolved in the upper and lower layers.
Explanation
| Test | Observation | Inference |
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(a) C + CCl\(_4\) water, shaken vigorously and mixture put in a burette (b)(i) A portion of upper layer + aq. NaOH solution (iii) Another portion of upper layer + pb(NO\(_3\))\(_2\) + dil. HNO\(_3\) (iv) Another portion of upper layer + AgNO\(_3\) + HNO\(_3\) (c) 2 - 3 drops of lower layer + starch solution
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Two immiscible layers separate with a blue aqueous in the upper lower layer. Blue ppt. insoluble in excess of aq. NaOH solution Blue ppt. insoluble in excess of aq. NH\(_3\) solution to form a deep blue solution White precipitate is formed No. ppt. Blue-black solution |
C is a mixture of 2 substances Cu\(^{2+}\) present Cu\(^{2+}\) confirmed Cl\(^{-}\) or SO\(_4^{2-}\) present Cl\(^{-}\) absent SO\(^{2-}_4\) present iodine present |
C is a mixture of copper (II) tetraoxosulphate (VI) and iodine